Maternal Long-Chain Polyunsaturated Fatty Acid Status During Early Pregnancy in Relation to Behavioral Problems of the Child at Age 5-6 and the role of the Autonomic Nervous System
in this Association Joya Smeets University of Amsterdam Masterthesis University of Amsterdam 10359796
Supervision by Jos Bosch and Tanja Vrijkotte Word count: 8791
1 Table of Contents Abstract ... 2 Introduction ... 2 Method ... 7 Materials ... 8 Covariates ... 10 Data analysis ... 10 Results ... 11 Discussion ... 24 References ... 27 Appendix ... 31
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Maternal Long-Chain Polyunsaturated Fatty Acid Status During Early Pregnancy in Relation to Behavioral Problems of the Child at Age 5-6 and the role of the Autonomic Nervous System
in this Association
Joya Smeets University of Amsterdam
Abstract
The present study examined the association between maternal long-chain polyunsaturated fatty acid (LC-PUFA) status during pregnancy and problem behavior later in life. This study further tested if the influence of maternal LC-PUFA status on problem behavior is mediated by the autonomic nervous system activity (ANS).
Data was collected as part of the ABCD-study. Maternal LC-PUFA status during early pregnancy (median gestation = 12.71, SD = 2.5 weeks) was available for 4336 women. Maternal LC-PUFA status was determined as docosahexenoic acid (DHA), arachidonic acid (AA) and eicosapentaenoic acid (EPA), and as the ratio of omega-6:omega-3 fatty acids. Child problem behavior was rated by the mother and/or teacher (n = 1717) at 5-6 years. Cardiac respiratory sinus arrhythmia (RSA), pre-ejection period (PEP) and heart rate (HR) were utilized as measures of ANS activity, and were available at 5-6 years.
The results indicate a direct effect of maternal LC-PUFA status on problem behavior as rated by the mother for DHA (b = -0.20, p < .05), EPA (b = -0.49, p < .05) and omega-6:omega-3 LC-PUFA (b = 0.31, p <.05). Statistical mediation was demonstrated for HR, but not other cardiac measures.
These results are consistent with a role of maternal LC-PUFA status in behavioral problems, when rated by the mother. These results were not observed when problem behavior was rated by the teacher. The data did not yield strong evidence supporting ANS activity as a possible mediator of the relationship between maternal LC-PUFA status and problem behavior.
Introduction
The fetal brain will grow rapidly during the second trimester and first year of life, during which a high quantity of fatty acids are integrated into the brain and other neural tissues (Janssen & Kiliaan, 2014; Schuchardt & Hahn, 2013). Key fatty acids for development of the fetal brain are the long-chain polyunsaturated fatty acids (LC-PUFA). These include eicosapentaenoic acid (EPA),
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docosahexaenoic acid (DHA), and arachidonic acid (AA). EPA and DHA belong to the omega-3 (n-3) family and AA to the omega-6 (n-6) family. These fatty acids are essential to neurodevelopmental processes such as synaptogenesis, myelination and membrane functioning (Georgieff, 2007). LC-PUFAs are essential fatty acids, which implies that they cannot be synthesized by the body, and the fetus receives the essential fatty acids from the maternal blood via placental delivery. After birth the essential fatty acids are delivered through breastmilk (Janssen & Kiliaan, 2014).
Considering the essential role of LC-PUFAs to fetal neurodevelopmental processes, it is not surprising that they have been linked to health and cognition after birth. For example, animal studies indicate that rats which experience a deficit in accrual of DHA during pregnancy are more likely to show problems with learning, memory, attention and emotion (Fedorova & Salem Jr., 2006; Moriguchi, Greiner, & Salem Jr., 2000; McCann & Ames, 2005). Research in humans likewise shows an association between maternal DHA status and cognitive development (Colombo et. al, 2004), as well as an association between maternal LC-PUFA supplementation and improvement in tests of global neurodevelopment (Makrides, Collins & Gibson, 2011). Research also describes beneficial effects of maternal LC-PUFA status during pregnancy on memory function of the child (Boucher et. al, 2011). These data point at the long-term importance of LC-PUFAs during the intra-uterine period for the development of cognitive abilities.
Research has also observed a link between LC-PUFAs and the development of behavioral problems. A review article by Frensham, Bryan and Parletta (2012) concluded that LC-PUFA supplementation has a beneficial effect on symptoms of attention deficit hyperactivity disorder (ADHD), and/or learning disabilities in children. These supplementation studies are in line with observational studies, of which an overview is provided in Table 1. These studies likewise suggest that maternal LC-PUFA status during pregnancy can have an effect that lasts beyond pregnancy.
Evidence of the role of LC-PUFAs during pregnancy has been extended further to include the autonomic nervous system (ANS). The ANS consists of two major branches. On the one hand the sympathetic system, associated with facilitating the body during activation, and on the other hand the parasympathetic system, associated with regulation of the body in rest. The activity of these two branches is usually in dynamic balance. Imbalance in the activity of these branches has been linked to an increased risk for cardiovascular disease (Thayer & Lane, 2007; Amerena & Julius, 1995).
A study by Pivik and colleagues (2009) observed an effect of LC-PUFA intake on the development of the ANS. They studied resting heart rate (HR) and heart rate variability (HRV) in the first 6 months of life in infants who were either breast-fed, or were fed formula with (milk-based) or without (soy-based) commercially supplemented DHA. Heart rate variability (HRV) is a measure of the parasympathetic branch of the ANS. They observed that the infants that were fed a DHA-deficient diet had higher HR and lower HRV, which indicated a decreased parasympathetic tone. Moreover, a
4 Table 1
Overview of Literature on the Role of Maternal LC-PUFA Status During Pregnancy and later Problem Behavior
Reference Study Design
Participants Time of blood sample
Variables measured Covariates included Findings
Loomans et. al, 2014 Prospective cohort study in the Netherlands N = 2553 5-6-year-old children During pregnancy (median 13 weeks’ gestation) SDQ scored by mother and teacher. Fatty acids: DHA, AA, EPA, n-6:n-3
Self-reported maternal ethnicity, maternal age, parity, pregnancy body mass index, smoking and alcohol consumption, maternal state-anxiety, maternal education and child’s sex and age.
Greater maternal concentrations of omega-3 fatty acid DHA decreased the risk for emotional symptoms in combined mother/teacher scores (OR 0.75; 95% CI 0.56-0.99; P = .05). Krabbendam et. al, 2007 Cohort follow-up study in the Netherlands N = 393 7-year-old children After birth in umbilical cord CBCL scored by parents (not specified which parent). Fatty acids: DHA, AA
Plasma DHA and AA concentrations at age 7, the child’s sex and birth weight, maternal smoking and drinking during pregnancy, and 3-level parental education.
Significant association between umbilical plasma DHA level and internalizing problem behavior (Beta = -0.15, P = 0.035), but not with externalizing problem
5 Note. SDQ = Strengths and Difficulties Questionnaire, DHA = docosahexaenoic acid, AA= arachidonic acid, EPA= eicosapentaenoic acid, n-6:n-3 = ratio of omega-6 and omega-3 fatty acids, CBCL = Child Behavior Checklist, LA = linoleic acid, ALA = alpha-linoleic acid
Kohlboeck et. al, 2011 Population-based birth cohort study in Germany N = 416 10-year-old children After birth in umbilical cord SDQ scored by parents (not specified which parent). Fatty acids: LA, ALA, AA, EPA, DHA, n-6:n-3
Sociodemographic
background of parents, risk factor variables during pregnancy, and actual dietary intake of fatty acids
A 1% increase in DHA in cord blood serum was found to decrease total difficulties by (exp)βadj = 0.93
(p <0.0001). Higher AA
concentrations were associated with fewer emotional symptoms
(exp)βadj = 0.94 (p = 0.03).
Steenweg-de Graaff et. al, 2014 Population-based cohort study in the Netherlands N = 6916 6-year-old children During pregnancy (median 20.5 weeks’ gestation) CBCL scored by parents & teacher Fatty acids: AA, EPA, DHA, n-3:n-6
Family income, maternal education level, pregnancy body mass index, age at enrollment, smoking and alcohol consumption during pregnancy, national origin, general psychiatric
symptoms in mid-pregnancy, parity, and marital status
Higher DHA and n-3:n-6 ratio were associated with fewer emotional problems using parent (ORDHA=
0.82, p = 0.02; ORn-3:n-6= 0.83, p =
0. 01) and combined parent/teacher scores (ORDHA= 0.79, p = 0.01;
ORn-3:n-6= 0.77, p < 0.01). Higher
AA was associated with more child behavioral problems using teacher (OR = 1.10, p = 0.04) and
combined parent/teacher scores (OR 1.12, p = 0.02).
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study by Colombo et al. (2011) found similar results. In this study, infants were fed one of four formulas, varying in DHA composition (0.0, 0.32, 0.64 and 0.96% of total fatty acids as DHA), from birth to 12 months of age. Infants assigned to the DHA supplemented conditions had lower HR than infants assigned to the unsupplemented condition. In addition, infants receiving DHA
supplementation performed better at an attention distribution task than children in the unsupplemented condition. These results suggest that DHA supplementation after birth has a positive effect on the development of the ANS as well as cognitive function.
The literature describes a role of the ANS in cognition (Gustafson, Colombo, & Carlson, 2008; Thayer et al., 2009; Kemp & Quintana, 2013), as well as in behavioral problems. A study on the effects of methylphenidate on cardiac health in children diagnosed with ADHD found that
unmedicated children with ADHD had a decreased vagal tone with significantly diminished HRV and higher HR (Buchorn et al., 2012). However, the authors did not find a negative impact of
methylphenidate on HRV, which lead them to suggest that higher HRs and reduced vagal tone might be a part of the pathophysiology of ADHD. Moreover, in a review by Beauchaine (2001), the role of both the parasympathetic and the sympathetic branch of the ANS in psychopathology were evaluated and it was suggested that activity of either branches could be regarded as a possible predisposition to psychopathology.
In summary, the literature demonstrates a role of LC-PUFAs during pregnancy in the development of the offspring. Availability of LC-PUFAs during gestation appears related to
behavioral problems, as well as ANS functioning. The latter has been speculated to contribute, in part, to behavioral problems. While these links have been demonstrated separately, they have yet to be tested in a single model. Therefore, the present study examined the mediating role of the ANS in the association between maternal LC-PUFA status and behavioral problems. Figure 1 presents the proposed model that will be tested in the present study. Firstly, this model proposed there is an association between maternal LC-PUFA status and behavioral problems. Based on the literature, it was expected to find evidence supporting this association. Second, the model proposed that ANS activity mediated the association between maternal LC-PUFA status and behavioral problems. It was expected that in the association between maternal LC-PUFA status and behavioral problems, ANS activity would act as a mediator. This would support the proposed model tested in the present study, and would be a starting point to examine ANS activity as a possible mechanism behind the
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Figure 1. Visualization of the model tested in the present study Method
Participants
Participants in this study were enrolled as part of the Amsterdam Born Children and their Development (ABCD) study (van Eijsden, Vrijkotte, Gemke, & van der Wal, 2011). In 2003 and 2004 all pregnant women living in Amsterdam were contacted to participate in this study. As shown in Figure 2, of the 12373 women invited to participate, 8266 filled out the pregnancy questionnaire. Of these, 7050 gave their permission for a follow-up, and 4389 participated in the biomarker study; 7043 gave permission for access to their and their child’s medical files. Detailed information on the cohort and procedures for data collection is provided elsewhere (van Eijsden et. al, 2011).
In 2010, all mothers were sent a follow-up questionnaire, approximately two weeks after their child’s 5th birthday. This questionnaire included items on the child’s health, development and
behavior, as well as items on family socio-demographics, maternal lifestyle and psychosocial conditions and family history of medical conditions. The questionnaire also included an informed consent sheet for the child’s participation in the ABCD health check. For children still living in Amsterdam, the health check was held at the child’s primary school. Children not living in
Amsterdam, and children enrolled in a small school with no room for the health check, were invited to a central location during the weekend and holidays. The health check consisted of a fasting capillary blood sample, physical measurements and a cognitive test battery. The physical measurement included measurements of ANS functioning, among other measurements (van Eijsden et. al, 2011).
Included in the present analyses were participants on which information on maternal LC-PUFA status, SDQ scored by either mother or teacher, and ANS measures was available. Twins and children with congenital malformations were excluded from the study. Additional information on inclusion criteria or the procedure of this study is presented in Figure 2. All participating mothers and children provided written informed consent.
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Figure 2. Flowchart of participants in this study Materials
Mothers that gave consent for the biomarker study (n = 4389) gave an additional blood sample during the routine blood collection for prenatal screening purposes. These blood samples were collected at a median of 13 weeks gestation (interquartile range (IQR) 12-14 weeks). Maternal LC-PUFA concentrations in plasma phospholipids were determined. The absolute amounts of omega-6 AA, omega-3 DHA, and omega-3 EPA (in mg/L plasma) were quantified on the basis of the recovery of an internal standard and expressed as a relative value (percentage of total amount of phospholipids-associated fatty acids). An extensive description of this procedure has been described elsewhere (van
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Eijsden, Hornstra, van der Wal, Vrijkotte, & Bonsel, 2008). The ratio omega-6:omega-3 was calculated by dividing the concentration AA (n-6) by the concentration DHA (n-3) and EPA (n-3) added together.
The SDQ was completed by the mother and primary/secondary school teacher when the child was at the age of 5/6 years. The SDQ is a short behavioral screening questionnaire suitable for 4- to 16-year-old subjects (Goodman, 1997). The SDQ consists of 5 subscales: emotional problems, conduct problems, hyperactivity/inattention problems, peer relationship problems, and prosocial behavior. Each subscale contains 5 questions with three response categories (not true, somewhat true, certainly true). To calculate the score for each subscale, the scores of the five items that make up that scale are summed, which generates a scale score ranging from 0 to 10. The scores for emotional problems, conduct problems, hyperactivity/inattention problems and peer relationship problems can be summed to generate a total difficulties score ranging from 0 to 40. The prosocial subscale is not incorporated in the total difficulties score since the absence of prosocial behaviors is conceptually different from the presence of psychological difficulties. A Dutch version of the SDQ was used in this study. The reliability and validity of the Dutch SDQ has been established in a Dutch population with satisfactory psychometric properties (van Widenfelt, Goedhart, Treffers, & Goodman, 2003). Inter-informant correlation between parent and teacher was calculated using Pearson’s r for overall problem behavior (r =0.52), emotional symptoms (r=0.32), conduct problems (r=0.36),
hyperactivity-inattention problems (r=0.54), peer problems (r=0.33) and prosocial behavior (r=0.23) (all p’s <0.01). ANS activity was assessed using an ambulatory device, the VU University Ambulatory Monitoring System (VU-AMS; Amsterdam, the Netherlands). Aspects of reliability and validity have been described previously (Vrijkotte, van Doornen, & de Geus, 2004). The procedure of this
measurement during the 5-6 year health check-up has been described previously (van Dijk et. al, 2010). In short, to start, the child is lying down in a supine position. Registration during this period lasted for at least 4 minutes. Next, the child was seated at a table for one minute of stabilization followed by another 4 minutes of registration. For this study only the recordings during 4 minutes supine position were used. The following outcome measures of ANS activity were assessed: HR, pre-ejection period (PEP) and respiratory sinus arrhythmia (RSA). All peaks in the ECG, scored by the software, have been checked, and R-peak markers were moved, inserted, or deleted when necessary. The software also automatically marked inspirations and expirations in the respiratory signals. These were also checked and edited if necessary. RSA was obtained from the resulting data as derivate of parasympathetic nervous system activity. RSA is the peak valley estimation which has been obtained automatically by subtracting the shortest inter beat interval during heart rate acceleration in the inspirational phase form the longest beat interval during deceleration in the expirational phase. Pre-ejection period (PEP) was used as a derivate of sympathetic nervous system activity. PEP is the time interval between the onset of ventricular depolarization (the Q wave onset in the ECG) and the
10 opening of the aortic waves (B-point in ICG) (Quigly & Stifter, 2006). HR, PEP and RSA were obtained from the 4-minute resting period in supine position.
Covariates
Potential confounds included in the present analyses were: maternal ethnicity (the
Netherlands, other Western country, non-Western country) (van Eijsden, Hornstra, van der Wal, & Bonsel, 2009) defined by country of birth of the pregnant woman and her mother, maternal age (years), parity (0, >1), pre-pregnancy body mass index (kg/m²) based on self-reported height and weight, smoking during pregnancy (no, <5 per day, ≥ 5 per day) and alcohol consumption during pregnancy (yes or no), maternal state anxiety (during pregnancy)(Spielberger, Gorsuch, & Lushene, 1970), maternal education (years after primary school), and child’s sex and age at SDQ administration (years). Birth weight (grams) and gestational age (weeks) were available from Youth Health Care Registration and the Dutch Perinatal Registration (www.perinatreg.nl). Information on infant feeding (no, 1-3 months of exclusive breastfeeding, >3 months of exclusive breastfeeding) was obtained from questionnaires (administered during infancy and when the child was 5 years of age).
Data analysis
Descriptive statistics were used to explore the association between maternal and child characteristics and maternal LC-PUFA status during pregnancy and tested using analysis of variance (ANOVA).
A non-response analysis was performed to compare maternal ethnicity, maternal age, parity, pre-pregnancy body mass index, smoking and alcohol consumption, maternal state anxiety and maternal education, and child’s sex, birth weight and gestational age at delivery between the group included in the present study and the non-response group. The non-response group consisted of all participants who were eligible for the present study (approached for the 5-year measurement round without congenital malformations and participated in the biomarker study), but were not included. Statistical differences were tested with ANOVA for continuous variables and chi-squared tests for categorical data.
Linearity was tested using four splines and likelihood ratio tests for each separate path of the model. No departure from linearity was found on the log odds scale between continuous outcomes and the maternal LC-PUFA status, nor for the log odds scale between continuous outcomes and ANS activity.
Thus, a multiple linear regression analysis was performed to test for the association between maternal PUFA status and behavioral problems, as well as the association between maternal LC-PUFA status and ANS activity, and between ANS activity and behavioral problems. Each of these associations was first examined by a multiple linear regression that accounted for gestational age at
11 blood sampling (Al et al., 1995) and the sex and age of the child at the time the SDQ was
administered (Model 1). Second, multiple linear regression analysis that included all covariates listed above (Model 2) were performed for the three separate associations. The scores on the SDQ for the mother and teacher were analyzed separately. This resulted in separate outcomes for the association between maternal LC-PUFA status and behavioral problems (mother/teacher) and for the association between the ANS and behavioral problems (mother/teacher).
To test for the hypothesized mediation effect described previously, mediation analysis was performed in Model 2. Mediation analysis was tested using the PROCESS tool for SPSS. This method has been extensively described elsewhere (Preacher & Hayes, 2004; Hayes, 2013). The proportion of the association between maternal LC-PUFA status and behavioral problems mediated by the ANS was calculated by dividing the indirect effect by the absolute total effect (the sum of the indirect effect and the direct effect) (Ditlevsen, Christensen, Lynch, Damsgaard, & Keiding, 2004). The mediation proportion represents the percentage change of regression coefficient when the mediator is added to the model.
Results
As shown in Table 2, nonresponse analysis on key variables revealed that mothers in the response group were on average 1.1 years older (p < .001), more often had a Dutch background (70.2% vs 59.0%; p < .001), were more often highly educated (53.6% vs 43.4%; p = .001), and scored lower on general anxiety (36.5 vs 37.3; p < .05) compared to mothers in the nonresponse group. The women in the response group consumed significantly more often alcohol than the women in the nonresponse group (30.1% vs 23.8%; p < .05).
The 1717 women included in this study were on average 31.9 years old. Of those 1717 women, 57.5% were nullipara, 21.2% were overweight or obese at the start of pregnancy, 70.2% were of Dutch origin, and 8.9% experienced a high amount of anxiety during pregnancy (Table 3).
The results from Table 3 indicate a certain pattern of LC-PUFA status. Young mothers (< 25 y), mothers with a lower education level, mothers with a higher pre-pregnancy BMI, mothers with a non-Western ethnicity and mothers with a higher level of anxiety had a significantly lower
concentration of EPA (n-3) and DHA (n-3), a significantly higher concentration of AA (n-6) and a significantly higher omega-6:omega-3 LC-PUFA. This pattern seems to be reversed for mothers who consumed alcohol during pregnancy. They had significantly higher concentrations of EPA (n-3) and DHA (n-3), and lower concentrations of AA (n-6) and a lower omega-6:omega-3 LC-PUFA. Multipara showed a higher concentration of AA (n-6), a lower concentration of DHA (n-3) and a higher omega-6:omega-3 LC-PUFA compared to nulliparous mothers. Mothers who did not breastfed their child had higher concentrations of AA (n-6) and a higher omega-6:omega-3 LC-PUFA than mothers that breastfed for more than 3 months after giving birth. Mothers who smoked during
12 pregnancy had lower concentrations of DHA (n-3) and higher omega-6:omega-3 LC-PUFA than mothers who did not smoke during pregnancy.
Table 2
Nonresponse analysis on key variables
Characteristics Response (n=1717) Mean/% ± SD Non response (n=1527) Mean/% ± SD p-value Ethnicity mother (%) The Netherlands Other Western country Other non-Western country
70.2 13.0 16.8 59.0 16.1 24.9 <0.001 Parity (% nullipara) 57.5 59.6 0.236 BMI (kg/m2) 23.0 ± 3.8 22.7 ± 3.7 0.095
Smoking during pregnancy (%) No < 5 ≥ 5 91.2 5.2 3.6 90.7 5.0 4.3 0.569
Alcohol consumption during pregnancy (% yes)
30.1 23.8 <0.001
STAI 36.5 ± 9.8 37.3 ± 10.0 <0.05
Education after primary school (%) 0-5 5-10 > 10 10.6 35.8 53.6 17.0 39.6 43.4 <0.001 Maternal age 31.9 ± 4.3 30.8 ± 4.7 <0.001 Sex (% girls) 51.1 50.9 0.886
13 Table 3
Characteristics of the study population on mean ± SD EPA (n-3), AA (n-6), DHA (n-3) and omega-6:omega-3 concentrations
Characteristics n (%) EPA (n-3) AA (n-6) DHA (n-3) n-6:n-3
Maternal age < 25 25-35 (reference) > 35 101 (5.9) 1301 (75.8) 315 (18.3) 0.41 ± 0.20*** 0.67 ± 0.42 0.73 ± 0.56 9.94 ± 1.54*** 9.18 ± 1.52 9.21 ± 1.61 4.07 ± 1.02*** 4.78 ± 1.12 4.69 ± 1.11 2.37 ± 0.78*** 1.81 ± 0.74 1.83 ± 0.61 Parity 0 ≥ 1 988 (57.5) 729 (42.5) 0.66 ± 0.43 0.66 ± 0.46 9.10 ± 1.50 9.39 ± 1.60*** 4.85 ± 1.11 4.54 ± 1.27*** 1.78 ± 0.80 1.94 ± 0.62*** BMI (during pregnancy)
< 18.5 18.5-24.9 (reference) 25-29.9 ≥ 30 59 (3.4) 1293 (75.4) 281 (16.4) 83 (4.8) 0.55 ± 0.31 0.69 ± 0.46 0.60 ± 0.34* 0.63 ± 0.53 9.07 ± 1.82 9.08 ± 1.48 9.69 ± 1.55*** 10.13 ± 1.80*** 4.57 ± 1.09 4.76 ± 1.14 4.72 ± 1.13 4.26 ± 0.82*** 1.88 ± 0.58 1.80 ± 0.77 1.94 ± 0.59* 2.16 ± 0.54***
Education after primary school (y) 0-5 5-10 > 10 (reference) 182 (10.6) 612 (35.8) 917 (53.6) 0.53 ± 0.46*** 0.64 ± 0.47** 0.71 ± 0.41 9.93 ± 1.79*** 9.33 ± 1.61** 9.03 ± 1.40 4.31 ± 1.23*** 4.63 ± 1.15*** 4.86 ± 1.07 2.23 ± 0.75*** 1.94 ± 0.94*** 1.71 ± 0.50 Ethnicity
The Netherlands (reference) Other Western country
1205 (70.2) 224 (13) 0.70 ± 0.41 0.70 ± 0.52 9.05 ± 1.43 8.95 ± 1.44 4.79 ± 1.09 4.78 ± 1.23 1.75 ± 0.52 1.86 ± 1.35
14 Note. EPA (n-3), AA (n-6) and DHA (n-3) levels were standardized at median gestational age at blood sampling (12.71 wk).
* p < 0.05 ** p < 0.01 ***p < 0.001
Other non-western country 288 (16.8) 0.51 ± 0.48*** 10.17 ± 1.74*** 4.40 ± 1.17*** 2.23 ± 0.68*** Anxiety during pregnancy (STAI)
≤ 35 (reference) 36-51 > 51 887 (51.9) 670 (39.2) 153 (8.9) 0.70 ± 0.42 0.63 ± 0.43** 0.60 ± 0.58* 9.14 ± 1.45 9.27 ± 1.59 9.53 ± 1.81* 4.79 ± 1.12 4.68 ± 1.11 4.52 ± 1.19* 1.80 ± 0.82 1.86 ± 0.59 2.02 ± 0.73** Exclusive breastfeeding (mo)
No 1-3 > 3 (reference) 378 (22.2) 459 (26.9) 868 (50.9) 0.66 ± 0.52 0.65 ± 0.43 0.67 ± 0.41 9.47 ± 1.56*** 9.26 ± 1.55 9.11 ± 1.53 4.67 ± 1.11 4.66 ± 1.14 4.76 ± 1.13 1.91 ± 0.63** 1.91 ± 1.02 1.79 ± 0.57 Alcohol consumption during pregnancy
No Yes 1201 (69.9) 516 (30.1) 0.63 ± 0.43 0.75 ± 0.45*** 9.33 ± 1.60 9.00 ± 1.38*** 4.64 ± 1.16 4.92 ± 1.03*** 1.92 ± 0.81 1.67 ± 0.46***
Smoking during pregnancy No (reference) < 5 per day ≥ 5 per day 1566 (91.2) 89 (5.2) 62 (3.6) 0.67 ± 0.45 0.65 ± 0.37 0.57 ± 0.38 9.23 ± 1.55 8.94 ± 1.49 9.63 ± 1.50 4.76 ± 1.12 4.43 ± 1.08* 4.27 ±1.26** 1.83 ± 0.74 1.90 ± 0.63 2.15 ± 0.65**
15 For the main analysis, a regression analysis was performed on all separate paths of the
hypothesized mediation effect. Table 4 shows the results of the regression analysis on the minimally adjusted (Model 1) and the fully adjusted model (Model 2) for the association between maternal LC-PUFA status and problem behavior reported by the mother. Model 1 yielded a significant association between concentration of DHA (n-3) and overall problem behavior, emotional symptoms,
hyperactivity/inattention symptoms and peer relationship problems. These associations remain significant, albeit attenuated, in Model 2. Model 1 showed a significant association between the concentrations of EPA (n-3) and overall problem behavior emotional problems,
hyperactivity/inattention symptoms and peer relationship problems. In Model 2, the association between EPA (n-3) and overall problem behavior, emotional symptoms and hyperactivity/inattention symptoms remained, albeit attenuated. Analysis on the association between the concentration of AA (n-6) and behavioral problems in Model 1 showed a significant association between AA (n-6) and overall problem behavior, hyperactivity/inattention symptoms and peer relationship problems. These associations did not remain significant in Model 2. The association between omega-6:omega-3 LC-PUFA in Model 1 showed significant associations between omega-6:omega-3 and overall problem behavior, conduct problems, hyperactivity/inattention problems and peer relationship problems. In Model 2, only the association between omega-6:omega-3 LC-PUFA and overall problem behavior as well as peer relationship problems remained. Here, a decline in β coefficient and p value was also observed.
Table 5 presents the results from regression analysis on Model 1 and Model 2 to test for the association between maternal LC-PUFA status and measures of ANS activity. Model 1 showed a significant association between DHA (n-3) and HR, as well as a significant association between the omega-6:omega-3 LC-PUFA and HR. In Model 2, these associations did not remain significant. No associations were found between maternal LC-PUFA status and either ANS measure.
Table 6 shows the regression analysis on Model 1 and Model 2 for the association between measures of the ANS activity and problem behavior reported by the mother. Analysis on Model 1 showed that there was a significant association between HR and emotional symptoms. This association remained in Model 2. Analysis on Model 2 showed there was a significant association between HR and hyperactivity/inattention symptoms. This association did not show as significant in Model 1.
Table 4
Association between maternal fatty acid concentrations in plasma phospholipids during pregnancy and children’s reported problem behavior by the mother (n = 1689)
SDQ Model 1 Model 2
16 Overall problem behavior
Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior -0.36 (-0.52; -0.20)*** -0.07 (-0.12; -0.02)** -0.03 (-0.08; 0.02) -0.15 (-0.24; -0.06)** -0.12 (-0.16; -0.07)*** 0.07 (-0.01; 0.14) -0.20 (-0.36; - 0.04)* -0.06 (-0.12; -0.01)* 0.01 (-0.05; 0.06) -0.09 (-0.19; -0.001)* -0.05 (-0.09; 0.001)* 0.05 (-0.02; 0.13) EPA (20:5n-3) (%)
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior -0.89 (-1.3; -0.48) *** -0.22 (-0.35; -0.09)** 0.01 (-0.12; 0.14) -0.44 (-0.67; -0.21)*** -0.24 (-0.37; -0.12)*** 0.11 (-0.08; 0.30) -0.49 (-0.89; -0.09)* -0.18 (-0.31; -0.05)** 0.07 (-0.06; 0.20) -0.30 (-0.53; -0.07)* -0.09 (-0.20; 0.03) 0.07 (-0.12; 0.26) AA (20:4n-6) (%)
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior 0.19 (0.07; 0.30)** -0.02 (-0.05; 0.02) 0.01 (-0.03; 0.05) 0.10 (0.04; 0.17)** 0.09 (0.06; 0.12)*** 0.02 (-0.03; 0.08) 0.01 (-0.11; 0.13) -0.04 (-0.07; 0.01) -0.02 (-0.06; 0.02) 0.05 (-0.02; 0.12) 0.02 (-0.02; 0.05) 0.04 (-0.02; 0.10) Omega-6:omega-3
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior 0.68 (0.43; 0.92)*** 0.07 (-0.01; 0.15) 0.08 (0.004; 0.16)* 0.25 (0.11; 0.38)** 0.28 (0.21; 0.35)*** -0.07 (-0.18; 0.05) 0.31 (0.06; 0.56)* 0.05 (-0.04; 0.13) 0.02 (-0.06; 0.11) 0.12 (-0.03; 0.26) 0.12 (0.05; 0.20)** -0.03 (-0.15; 0.09)
Note. Model 1 was adjusted for gestational age at blood sampling, sex and child’s age at SDQ, Model 2 was additionally adjusted for ethnicity, parity, pregnancy BMI, smoking and alcohol consumption during pregnancy, maternal state anxiety, maternal education, infant feeding, gestational age at birth and birth weight. Values are β coefficient (95% CI) unless otherwise noted.
*p < 0.05 **p < 0.01 ***p < 0.001
17 Association between maternal fatty acid concentrations in plasma phospholipids during pregnancy and measures of the autonomic nervous system of the child at age 5-6 (n= 1690)
ANS Model 1 Model 2
DHA (22:6n-3) (%) HR PEP RSA -0.48 (-0.89; -0.06)* -0.15 (-0.53; 0.22) 0.32 (-2.36; 2.99) -0.36 (-0.823; 0.03) -0.24 (-0.63; 0.15) 0.49 (-2.30; 3.29) EPA (20:5n-3) (%) HR PEP RSA -0.82 (-1.88; 0.24) - 0.27 (-1.23; 0.69) 2.16 (-4.65; 8.97) -0.48 (-1.56; 0.60) -0.44 (-1.42; 0.53) 1.35 (-5.61; 8.32) AA (20:4n-6) (%) HR PEP RSA 0.28 (-0.03; 0.58) -0.24 (-0.51; 0.04) -0.29 (-2.24; 1.67) 0.13 (-0.20; 0.46) -0.18 (-0.48; 0.12) -0.89 (-2.99; 1.21) Omega-6:omega-3 HR PEP RSA 0.86 (0.21; 1.50)** -0.26 (-0.84; 0.32) -1.22 (-5.34; 2.90) 0.55 (-0.13; 1.23) -0.12 (-0.73; 0.50) -1.62 (-6.00; 2.77)
Note. HR, mean heart rate during rest in supine position in beats per minute; PEP, mean PEP during rest in supine position in milliseconds; RSA, mean RSA during rest in supine position in milliseconds. Model 1 was adjusted for gestational age at blood sampling, sex and child’s age at SDQ, Model 2 was additionally adjusted for ethnicity, parity, pregnancy BMI, smoking and alcohol consumption during pregnancy, maternal state anxiety, maternal education, infant feeding, gestational age at birth and birth weight. Values are β coefficient (95% CI) unless otherwise noted.
*p < 0.05 **p < 0.01
Table 6
The cross-sectional association between measures of the autonomic nervous system and children’s reported problem behavior by the mother at age 5-6 (n = 1708)
SDQ Model 1 Model 2
HR (beats/min)
Overall problem behavior Emotional symptoms Conduct problems 0.01 (-0.01; 0.03) 0.01 (0.003; 0.02)** 0.00 (-0.01; 0.01) 0.003 (-0.02; 0.02) 0.01 (0.001; 0.01)** -0.002 (-0.01; 0.004)
18 Hyperactivity/inattention
Peer relationship problems Prosocial behavior -0.01 (-0.02; 0.004) 0.01 (0.00; 0.01) -0.004 (-0.01; 0.004) -0.01 (-0.02; 0.00)* 0.002 (-0.003; 0.01) -0.004 (-0.01; 0.01) PEP (msec)
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior -0.01 (-0.03; 0.02) -0.01 (-0.01; -0.00) -0.001 (-0.01; 0.01) 0.004 (-0.01; 0.02) -0.003 (-0.01; 0.003) 0.002 (-0.01; 0.01) -0.001 (-0.02; 0.02) -0.01 (-0.01; 0.001) 0.00 (-0.01; 0.01) 0.01 (-0.01; 0.02) 0.00 (-0.01; 0.01) 0.001 (-0.01; 0.01) RSA (msec)
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior 0.00 (-0.003; 0.003) -0.001 (-0.001; 0.001) 0.00 (-0.001; 0.001) 0.00 (-0.001; 0.002) 0.00 (-0.001; 0.001) 0.001 (0.00; 0.002) 0.00 (-0.002; 0.003) 0.00 (-0.001; 0.001) 0.00 (-0.001; 0.001) 0.001 (-0.001; 0.002) 0.00 (-0.001; 0.00) 0.001 (0.00; 0.002)
Note. HR, mean heart rate during rest in supine position in beats per minute; PEP, mean PEP during rest in supine position in milliseconds; RSA, mean RSA during rest in supine position in milliseconds. Model 1 was adjusted for gestational age at blood sampling, sex and child’s age at SDQ, Model 2 was additionally adjusted for ethnicity, parity, pregnancy BMI, smoking and alcohol consumption during pregnancy, maternal state anxiety, maternal education, infant feeding, gestational age at birth and birth weight. Values are β coefficient (95% CI) unless otherwise noted.
*p < 0.05 **p < 0.01
Mediation analyses were performed to test for the hypothesized mediation effect of ANS activity on the relationship between maternal LC-PUFA status and behavioral problems. Mediation analysis on Model 2 showed that maternal LC-PUFA status indirectly influenced problem behavior later in life through its effect on the ANS. This effect was only found for three subscales of the SDQ and with HR as a measure of ANS activity.
Figure 3 represents the mediation effect of HR on the association between maternal DHA (n-3) status and emotional problems as reported by mother. A bias-corrected bootstrap confidence interval for the indirect effect (b = - 0.003) based on 1000 bootstrap samples was entirely below zero (-0.0091 to - 0.0002). The proportion mediated by HR explained about 5% of the association between maternal DHA (n-3) status and emotional symptoms (-0.003/-0.063*100%). Figure 4 shows the
19 mediation effect of HR on the association between maternal omega-6:omega-3 LC-PUFA and
emotional problems rated by the mother. A bias-corrected bootstrap confidence interval for the indirect effect of maternal omega-6:omega-3 LC-PUFA on emotional symptoms (b = 0.004) based on 1000 bootstrap samples was entirely above zero (0.0002 to 0.0147). The proportion mediated by HR explained 9% of the association between maternal omega-6:omega-3 LC-PUFA and emotional
symptoms (0.004/0.044*100%). Lastly, figure 5 denotes the mediation effect of HR on the association between omega-6:omega-3 LC-PUFA and hyperactivity/inattentions symptoms rated by the mother. A bias-corrected bootstrap confidence interval for the indirect effect of maternal omega-6:omega-3 LCPUFA on hyperactivity/inattention symptoms (b = 0.0006) was entirely below zero (0.0102 to -0.0002). The proportion mediated by HR explained about 5% of the association between omega-6:omega-3 LC-PUFA and hyperactivity/inattention symptoms (-0.006/0.114*100%).
Figure 3. Mediation effect of heart rate (HR) on the relationship between docosahexaenoic acid (DHA) and reported emotional problems by the mother (Model 2)
20 Figure 4. Mediation effect of heart rate (HR) on the relationship between the ratio of omega-6:omega-3 (n-6:n-omega-6:omega-3) and reported emotional problems by the mother (Model 2)
Figure 5. Mediation effect of heart rate (HR) on the relationship between the ratio of omega-6:omega-3 (n-6:n-omega-6:omega-3) and reported hyperactivity symptoms by the mother (Model 2)
Analysis on the association between maternal LC-PUFA status and behavioral problems as rated by the teacher were also performed. Multiple regression analysis on the separate paths of the hypothesized mediation effect indicated few associations between maternal LC-PUFA status and
21 behavioral problems, or between measures of ANS activity and behavioral problems. Tables regarding the findings can be found in the appendix.
Mediation analyses were also performed for the scores on the SDQ as scored by the teacher. Analyses on the fully adjusted model (Model 2) showed quite similar results to the results from the analyses on the SDQ scores from the mother. Mediation analysis showed that HR was a mediator of the association between maternal DHA (n-3) status and overall problem behavior as rated by the teacher (Figure 6). A bias-corrected bootstrap confidence interval for the indirect effect (b = 0.01) based on 1000 bootstrap samples was entirely above zero (0.0003 to 0.0362). The proportion mediated by HR explained over 60% of the association between DHA (n-3) and overall problem behavior (0.01/0.016)*100). Figure 7 shows HR as a mediator in the association between maternal DHA (n-3) status and hyperactivity/inattention symptoms rated by the teacher. A bias-corrected bootstrap confidence interval for the indirect effect (b = 0.01) based on 1000 bootstrap samples was entirely above zero (0.0015 to 0.0250). The proportion mediated by HR explained 20% of the association between maternal DHA (n-3) status and hyperactivity/inattention symptoms (0.01/0.05*100). Figure 8 represents the mediation effect of HR on the association between maternal omega-6:omega-3 LC-PUFA and overall problem behavior rated by the teacher. A bias-corrected bootstrap confidence interval for the indirect effect (b = -0.02) based on 1000 bootstrap samples was entirely below zero (-0.0546 to -0.0007). The proportion mediated by HR explained about 17% of the association between omega-6:omega-3 LC-PUFA and overall problem behavior (-0.02/-0.12*100). Figure 9 shows the mediation effect of HR on the association between maternal omega-6:omega-3 LC-PUFA and hyperactivity/inattention symptoms rated by the teacher. A bias-corrected bootstrap confidence interval for the indirect effect (b = -0.01) based on 1000 bootstrap samples was entirely below zero (-0.0433 to -0.0021). The proportion mediated by HR explained about 7% of the association between omega-6:omega-3 LC-PUFA and overall problem behavior (-0.01/-0.15*100).
22 Figure 6. Mediation effect of heart rate (HR) on the relationship between docosahexaenoic acid (DHA) and overall problem behavior rated by the teacher (Model 2)
Figure 7. Mediation effect of heart rate (HR) on the relationship between docosahexaenoic acid
23 Figure 8. Mediation effect of heart rate (HR) on the relationship between the ratio omega-6:omega-3 (n-6:n-3) and overall problem behavior rated by the teacher (Model 2)
Figure 9. Mediation effect of heart rate (HR) on the relationship between the ratio omega-6:omega-3 (n-6:n-3) and hyperactivity/inattention symptoms reported by the teacher (Model 2)
24 Discussion
The present study examined whether ANS activity was a possible mediator in the association between maternal LC-PUFA status and problem behavior. First of all, the results indicated there was a link between maternal LC-PUFA status and behavioral problems rated by the mother. The results did not indicate a link between maternal LC-PUFA status and behavioral problems, when rated by the teacher. The results do not provide evidence supporting ANS activity as a mediator in the association between maternal LC-PUFA status and behavioral problems. Mediation effects could only be found for HR. These effects were present when problem behavior was rated by the mother as well as the teacher, but on different subscales of the SDQ. The results did not provide evidence for mediation effects of sympathetic or parasympathetic activity.
Results from the present study were largely in line with the results from previous studies on the association between maternal LC-PUFA status and behavioral problems (Kohlboeck et al., 2007; Krabbendam et al., 2007; Steenweg- de Graaff et al., 2014). There seems to be a general agreement on the importance of maternal DHA concentration in the association between maternal LC-PUFA status and behavioral problems. The present study was not able to yield evidence linking maternal AA concentration and behavioral problems, which is in line with results from Krabbendam et al. (2007). In contrast, results from Kohlboeck et al. (2007) and Steenweg- de Graaff et al. (2014) did indicate an association between maternal AA concentration and emotional problems. Differences between studies are not surprising and could be the result of differences in sample size, timing of blood sample and the age of the child at the time of measurement, among other variables.
LC-PUFAs have been linked to neurodevelopmental processes that affect cognition, behavioral problems and ANS activity in the offspring. The present study sought to combine these links in a mediation model as a possible mechanism behind these links, but was not able to yield evidence to support this model. Absence of evidence for this model might be because the effects of maternal LC-PUFA status on the development of the child, with DHA in particular, are more complex than examined in the present study. Meta-analysis on sleep, cognition and behavioral problems concluded that insufficient sleep is associated with deficits in higher order cognitive functions and increased behavioral problems (Astill, van der Heijden, van IJzendoorn, & van Someren, 2012). Sleep patterns have also been linked to maternal DHA status, which suggests a greater maturation of the CNS (Cheruku et al., 2002). Furthermore, the ANS has been proposed as a mediator in the association between maternal LC-PUFA status and cognitive functioning in the offspring (Gustafson et al., 2008; Gustafson et al., 2013). It might be possible that DHA and behavioral problems are associated because DHA is related to CNS development and maturity, which in turn influences sleep patterns as well as cognitive functioning. By influencing the sleep patterns, higher order cognitive functioning is affected and behavioral problems are increased. Future research from the ABCD-study could explore the
25 possibility of the role of sleep patterns and cognitive functioning in the associations explored in the present study.
Surprisingly, the present study observed a negative association between HR and hyperactivity/inattention symptoms. This is in contrast to a study by Buchorn et al. (2012) that observed higher HR in unmedicated children diagnosed with ADHD compared to children without ADHD. A possible explanation for this unexpected finding could be that the present study did not include many confounding variables regarding the ANS measures, thereby enabling the possibility of finding a spurious association. However, this association was observed for SDQ scores from both the mother and the teacher, and should be addressed in future research. It would be preferable to include more variables potentially influencing HR in future research regarding the role of the ANS in behavioral problems.
The difference between the results from separate analysis on the SDQ rated by the mother and teachers should be addressed. Results indicating a link between maternal LC-PUFA status and
behavioral problems rated by the mother, but not when rated by the teacher, might be due to residual confounding. But the difference might also indicate there is no consensus between the two raters. Inter-informant correlations between parent and teacher were medium (van Widenfelt et al., 2003), which might be due to a difference in rating of the child’s behavior (Stone, Otten, Engels, Vermulst, & Janssens, 2010). This difference might stem from a difference in perception of the child, but it could also be possible that the child truly behaves differently in both situations. There is need for a valid method of combining the scores from the two raters, as there is no consensus on combining these scores from previous studies on the association between maternal LC-PUFA status and behavioral problems (Loomans et al., 2014; Steenweg- de Graaff et al., 2014). Further research is needed to assess a valid method of combining scores from multiple raters on the SDQ or a similar questionnaire.
A few strengths of the present study should be noted. Firstly, this study is part of a community based multi-ethnic birth cohort, which clearly gives strengths in terms of statistical power. Moreover, the ABCD-study is very broad, which gives opportunity to adjust for many different covariates that are potentially influencing the associations of interest. Lastly, maternal LC-PUFA status was determined using a blood sample taken during pregnancy, which is a more accurate measure of maternal LC-PUFA status during pregnancy than an estimate from a questionnaire or a blood sample taken after delivery (Hibbeln et al., 2007; Krabbendam et al., 2007; Kohlboeck et al., 2011).
The present study also has limitations. First, child problem behavior was rated using a brief questionnaire. Although the SDQ has satisfactory psychometric properties (van Widenfelt et al., 2003), the SDQ is a screening questionnaire, not a diagnostic instrument. Elevated scores on the SDQ do not necessarily imply the presence of psychopathology. Furthermore, children from the present study were at an age of transferring from kindergarten to elementary school. Elementary school is more demanding than kindergarten in terms of attention and discipline. Difficulty adapting to the new
26 regime could have had an effect on the child’s behavior at home, but also on the rating of the behavior from the teacher. There is a possibility of temporary stressors influencing scores on the SDQ, as these were available from a single moment in time. Future research from the ABCD study could compare the SDQ scores from phase 3 and phase 4 to determine the stability of SDQ scores overtime. Second, nonresponse analysis showed differences between mothers in the response and nonresponse group on key variables. Mothers in the response group had higher education, had more often Western or Dutch ethnicity and were on average older than the mothers in the non-response group, which indicates a selection towards higher social economic participants. Key variables corresponding to the non-response group were associated with a less favorable maternal LC-PUFA status. It might be possible that the level of reported problem behavior was an underestimation as children more prone to the development of problem behavior were underrepresented. This selection-bias could have caused an attenuated effect and should be addressed in future research. Third, the developing brain is particularly vulnerable to nutritional fluctuations between 24 and 42 weeks gestation, as a high quantity of fatty acids are integrated into the brain and other neural tissues of the fetus (Dobbing, 1990; Rao & Georgieff, 2000; Schuchardt & Hahn, 2013). The present study collected a blood sample well before this period, which might limit the current findings, considering there is no blood sample available from this particularly vulnerable period. In future research, it would be preferable to obtain one or more blood samples taken during the vulnerable period. This would provide a more accurate measure of maternal LC-PUFA status that is associated with an important developmental period for the fetal brain. Lastly, current LC-PUFA intake has been associated with HR and mental functioning (Burri & Berge, 2013; Colombo et al., 2011), but was not included in the present study. This could be regarded as a possible limitation to the current study. However, research indicates that the influence of current LC-PUFA status on the association between maternal LC-PUFA status and behavioral problems might be limited (Krabbendam et al., 2007), suggesting a long-term effect of maternal LC-PUFA status regardless of current LC-PUFA status.
In conclusion, the present study was not able to find evidence supporting ANS activity as a mediator in the association between maternal LC-PUFA status and behavioral problems. Further research is needed to determine a possible mechanism behind the association between maternal LC-PUFA status and behavioral problems in the offspring. Results indicating an association between maternal LC-PUFA status and behavioral problems are to be interpreted with caution, as residual confounding cannot be ruled out. The present study adds to already existing literature and emphasizes on the importance of the fetus’ nutritional needs during pregnancy.
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31 Appendix
Table 1
Association between maternal fatty acid concentrations in plasma phospholipids during pregnancy and children’s reported problem behavior by primary school teacher (n = 1453)
SDQ Model 1 Model 2
DHA (22:6n-3) (%) Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior -0.04 (-0.25; 0.16) -0.04 (-0.11; 0.03) 0.003 (-0.05; 0.06) 0.03 (-0.08; 0.14) -0.03 (-0.09; 0.04) -0.06 (-0.15; 0.04) 0.02 (-0.19; 0.22) -0.04 (-0.12; 0.03) 0.01 (-0.04; 0.07) 0.05 (-0.06; 0.17) -0.003 (-0.07; 0.06) -0.06 (-0.16; 0.04) EPA (20:5n-3) (%)
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior -0.34 (-0.83; 0.15) -0.09 (-0.27; 0.09) 0.07 (-0.21; 0.07) -0.03 (-0.31; 0.24) -0.15 (-0.30; 0.00) -0.01 (-0.24; 0.23) -0.15 (-0.66; 0.34) -0.04 (-0.22; 0.14) -0.06 (-0.19; 0.08) 0.05 (-0.23; 0.32) -0.10 (-0.25; 0.05) -0.02 (-0.26; 0.22) AA (20:4n-6) (%)
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior 0.06 (-0.09; 0.20) 0.003 (-0.05; 0.06) 0.02 (-0.02; 0.06) -0.001 (-0.08; 0.08) 0.03 (-0.01; 0.08) 0.03 (-0.04; 0.10) -0.04 (-0.19; 0.12) -0.003 (-0.06; 0.05) 0.01 (-0.04; 0.05) -0.04 (-0.13; 0.04) 0.01 (-0.04; 0.05) 0.04 (-0.03; 0.12) Omega-6:omega-3
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior 0.04 (-0.26; 0.34) 0.05 (-0.06; 0.16) -0.02 (-0.10; 0.07) -0.09 (-0.25; 0.08) 0.09 (-0.003; 0.18) 0.04 (-0.11; 0.19) -0.12 (-0.43; 0.20) 0.04 (-0.07; 0.16) -0.04 (-0.13; 0.04) -0.16 (-0.33; 0.02) 0.04 (-0.06; 0.14) 0.06 (-0.10; 0.21)
Note. Model 1 was adjusted for gestational age at blood sampling, sex and child’s age at SDQ, Model 2 was additionally adjusted for ethnicity, parity, pregnancy BMI, smoking and alcohol consumption
32 during pregnancy, maternal state anxiety, maternal education, infant feeding, gestational age at birth and birth weight. Values are β coefficient (95% CI) unless otherwise noted.
Table 2
The association between measures of the autonomic nervous system and children’s problem behavior reported by teacher (n = 1469)
Note. HR, mean heart rate during rest in supine position in beats per minute; PEP, mean PEP during rest in supine position in milliseconds; RSA, mean RSA during rest in supine position in milliseconds. Model 1 was adjusted for gestational age at blood sampling, sex and child’s age at SDQ, Model 2 was additionally adjusted for ethnicity, parity, pregnancy BMI, smoking and alcohol consumption during pregnancy, maternal state anxiety, maternal education, infant feeding, gestational age at birth and birth weight. Values are β coefficient (95% CI) unless otherwise noted.
*p < 0.05 **p < 0.01
SDQ Model 1 Model 2
HR (beats/min)
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior -0.02 (-0.42; 0.00)* 0.003 (-0.01; 0.01) -0.01 (-0.01; 0.00) -0.02 (-0.03; -0.01)** -0.001 (-0.01; 0.01) 0.003 (-0.01; 0.01) -0.03 (-0.05; -0.003)* 0.003 (-0.01; 0.01) -0.01 (-0.01; 0.00) -0.02 (-0.03; -0.01)** -0.001 (-0.01; 0.01) 0.003 (-0.01; 0.01) PEP (msec)
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior -0.002 (-0.03; 0.02) -0.002 (-0.01; 0.01) -0.004 (-0.01; 0.003) -0.003 (-0.02; 0.01) 0.01 (-0.002; 0.01) -0.01 (-0.02; 0.01) -0.002 (-0.03; 0.02) -0.004 (-0.01; 0.01) -0.003 (-0.01; 0.004) -0.002 (-0.02; 0.01) 0.01 (-0.001; 0.02) -0.01 (-0.02; 0.01) RSA (msec)
Overall problem behavior Emotional symptoms Conduct problems Hyperactivity/inattention Peer relationship problems Prosocial behavior 0.001 (-0.002; 0.01) 0.00 (-0.001; 0.001) 0.00 (-0.001; 0.001) 0.002 (0.00; 0.004) -0.001 (-0.002; 0.001) 0.001 (-0.001; 0.002) 0.001 (-0.003; 0.004) 0.00 (-0.002; 0.001) 0.00 (-0.001; 0.001) 0.002 (0.00; 0.004) -0.001 (-0.002; 0.00) 0.001 (-0.001; 0.002)
