Marcel F. van der Wal

Cohort Profile: The Amsterdam Born Children and their Development (ABCD) Study

In 2000, a study among pregnant women in Amsterdam revealed large ethnic disparities in birth outcomes that were consistent with previous findings in both The Netherlands and other Western countries. So far, conventional risk factors such as low maternal socioeconomic status (SES), smoking or body mass index (BMI) could not explain these disparities. These results, in conjunction with increasing evidence of the longterm implications of adverse pregnancy outcomes (fetal origins of disease hypothesis), formed the basis of the Amsterdam Born Children and their Development (ABCD) study, which was established in 2003. This large prospective population-based cohort study examines the association between maternal lifestyle, medical, psychosocial and environmental conditions during pregnancy and children’s health at birth as well as in later life. Specific attention is paid to ethnic disparities. Consequently, the study has detailed measurements of ethnic background, including country of birth of the pregnant woman herself, country of birth of her parents and ethnic identity. The study is a collaboration between the Public Health Service of Amsterdam and the two university medical centres in Amsterdam [Academic Medical Center (AMC) and VU University Medical Center (VUmc)], and has been implemented in cooperation with hospitals and midwives, Youth Health Care (YHC) centres, primary schools and the University of Tilburg.

Psychosocial problems and continued smoking during pregnancy

The present study examined the association of several psychosocial problems with continued smoking during pregnancy. Based on a population-based cohort study among pregnant women in Amsterdam (n=8266), women who smoked before pregnancy were included in this study (n=1947). Women completed a questionnaire around the 12th week of gestation. Based on whether they smoked in the past week, participants were categorized as quitters or non-quitters. Depressive symptoms (CES-D), anxiety (STAI), pregnancy-related anxiety, job strain, parenting stress and physical/sexual violence were measured. Multiple logistic regression analyses were performed. After adjustment for sociodemographic and smoking-related covariates, low and high levels of pregnancy-related anxiety, exposure to physical/sexual violence, and high job strain were significantly associated with continued smoking during pregnancy. Intensive and comprehensive smoking cessation programs are required for pregnant women, which includes the management of psychosocial problems.

First-Trimester Working Conditions and Birthweight: A Prospective Cohort Study

OBJECTIVES We investigated the relationship between womens first-trimester working conditions and infant birthweight. METHODS Pregnant women (N = 8266) participating in the Amsterdam Born Children and Their Development study completed a questionnaire gathering information on employment and working conditions. After exclusions, 7135 women remained in our analyses. Low birthweight and delivery of a small-for-gestational-age (SGA) infant were the main outcome measures. RESULTS After adjustment, a workweek of 32 hours or more (mean birthweight decrease of 43 g) and high job strain (mean birthweight decrease of 72 g) were significantly associated with birthweight. Only high job strain increased the risk of delivering an SGA infant (odds ratio [OR] = 1.5; 95% confidence interval [CI] = 1.1, 2.2). After adjustment, the combination of high job strain and a long workweek resulted in the largest birthweight reduction (150 g) and the highest risk of delivering an SGA infant (OR = 2.0; 95% CI = 1.2, 3.2). CONCLUSIONS High levels of job strain during early pregnancy are associated with reduced birthweight and an increased risk of delivering an SGA infant, particularly if mothers work 32 or more hours per week.

Stress and Emotional Problems During Pregnancy and Excessive Infant Crying

Objective: There is evidence that stress and emotional problems during pregnancy are related to adverse health outcomes of the child at birth and in later life. The aim of this study was to determine the association between stress and emotional problems during pregnancy and excessive infant crying. Methods: From an initial sample of 8266 pregnant women, a follow-up sample of 4976 women and their 3- to 6-month-old babies was examined. Depressive symptoms, pregnancy related anxiety, parenting stress, and job strain during pregnancy were all univariately and multivariately associated with excessive infant crying (adjusted odds ratios between 1.69 and 2.23). Results: Women with three or four of these antenatal risks were more likely to have an infant who cries excessively than women with no antenatal risks (adjusted odds ratio of 4.89). Conclusion: In conclusion, stress and emotional problems during pregnancy increase the chances of having an excessively crying baby. Women with multiple antenatal risk factors are at particular risk.

Maternal cortisol and offspring birthweight: results from a large prospective cohort study

Maternal psychosocial problems may affect fetal growth through maternal cortisol. This large prospective cohort study examined among 2810 women (1) the association of maternal cortisol levels with offspring birthweight and small for gestational age (SGA) risk and (2) the mediating role of maternal cortisol on the relation between maternal psychosocial problems and fetal growth. Pregnant women in Amsterdam were approached during their first prepartum visit (+/-13 weeks gestation). Total maternal cortisol level was determined in serum and maternal psychosocial indicators were collected through a questionnaire. Maternal cortisol levels were negatively related to offspring birthweight (B=-0.35; p<.001) and positively to SGA (OR=1.00; p=.027); after adjustment (for gestational age at birth, infant gender, ethnicity, maternal age, parity, BMI, and smoking), these effects were statistically insignificant. Post hoc analysis revealed a moderation effect by time of day: only in those women who provided a blood sample < or =09:00h (n=94), higher maternal cortisol levels were independently related to lower birthweights (B=-0.94; p=.025) and a higher SGA risk (OR=1.01; p=.032). Maternal psychosocial problems were not associated with cortisol levels. In conclusion, although an independent association between maternal cortisol levels in early pregnancy and offspring birthweight and SGA risk was not observed, exploratory post hoc analysis suggested that the association was moderated by time of day, such that the association was only present in the early morning. The hypothesis that maternal psychosocial problems affect fetal growth through elevated maternal cortisol levels could not be supported.

Traffic-related air pollution and pregnancy outcomes in the Dutch ABCD birth cohort study

Objectives There is growing evidence for an adverse effect of maternal exposure to air pollution on pregnancy outcomes. As European data on this topic are limited, the aim of this study was to evaluate the impact of maternal exposure to traffic-related air pollution during different periods of pregnancy on preterm birth and fetal growth. Methods We estimated maternal residential exposure to NO2 during pregnancy (entire pregnancy and trimesters) for 7600 singleton births participating in the Amsterdam Born Children and their Development (ABCD) prospective birth cohort study by means of a temporally adjusted land-use regression model. Associations between air pollution concentrations and preterm birth and fetal growth (expressed as small for gestational age and term birth weight) were analysed by means of logistic and linear regression models with and without adjustment for maternal physiological, lifestyle and sociodemographic characteristics. Results There was no indication of an increase in preterm birth among highly exposed women. Children of mothers with NO2 levels in the highest exposure category on average had the highest term birth weight of all children and were among those with the lowest risk of being small for gestational age with little indication of a dose–response relationship. Conclusions In this study, there is no evidence for a harmful effect of estimated maternal exposure to traffic-related air pollution during pregnancy on pregnancy outcomes such as preterm birth, small for gestational age and term birth weight.

Caffeine Intake During Pregnancy and Risk of Problem Behavior in 5- to 6-Year-Old Children

BACKGROUND AND OBJECTIVE: Human studies that have investigated the association between caffeine intake during pregnancy and offspring’s behavioral outcomes are scant and inconclusive. We prospectively investigated the association between maternal caffeine intake during pregnancy and children’s problem behavior at age 5 to 6 years. Mediation by fetal growth restriction and gestational age as well as effect modification by the child’s gender and maternal smoking was tested. METHODS: In a community based multiethnic birth cohort, dietary caffeine intake (coffee, caffeinated tea, and cola) was measured (maternal self-report, n = 8202) around the 16th week of gestation. At age 5, children’s overall problem behavior, emotional problems, conduct problems, hyperactivity/inattention problems, peer relationship problems, and prosocial behavior were rated by both mother and teacher (n = 3439) with the Strengths and Difficulties Questionnaire. Analyses were adjusted for maternal age, ethnicity, cohabitant status, education, smoking and alcohol consumption during pregnancy, child’s gender, family size, and prenatal maternal anxiety. RESULTS: Caffeine intake was not associated with a higher risk for behavior problems or with suboptimal prosocial behavior. No evidence was found for mediation by fetal growth restriction or gestational age, nor for effect modification by the child’s gender. CONCLUSIONS: Results did not provide evidence for developmental programming influences of intrauterine exposure to caffeine on offspring’s problem behavior at age 5. Present results give no indication to advise pregnant women to reduce their caffeine intake to prevent behavior problems in their children.

Ethnic differences in term birthweight: the role of constitutional and environmental factors

It is not clear to what extent ethnic differences in the term birthweight distribution are constitutional or pathological. This study explored term birthweight heterogeneity between ethnic groups and the explanatory role of constitutional and environmental factors. As part of a prospective cohort study, the Amsterdam Born Children and their Development study, 8266 pregnant women filled out a questionnaire during early pregnancy. Ethnic groups were categorised as: native Dutch group; first and second generation Surinamese, Antillean, Turkish, Moroccan, Ghanaian and other non-Dutch groups. Only singleton livebirths with >or=37.0 weeks of gestation and with complete data were included for analysis (n = 7118). We performed linear regression analyses to estimate the association between ethnicity and, for gestational age, standardised birthweight at term, adjusted for constitutional (fetal gender, parity, maternal age, maternal height) and environmental (education, cohabitation status, maternal body mass index, smoking, alcohol consumption, depression, work stress) determinants respectively. Mean birthweight ranged from 3223 g (second generation Surinamese newborns) to 3548 g (Dutch newborns). Adjustment for constitutional factors substantially reduced the ethnic differences in birthweight, while adjustment for environmental factors provided little additional explanation. Surinamese [first generation: regression coefficient (b) = -98.3 g, P < 0.001; second generation: b = -159.3 g, P < 0.001], first generation Antillean (b = -102.0 g, P = 0.037), and Ghanaian newborns (b = -120.7 g, P = 0.001) remained significantly smaller than Dutch newborns after adjustment for all determinants. Term birthweight differences between Dutch newborns and Turkish, Moroccan and other non-Dutch newborns were largely explained by constitutional rather than environmental determinants, limiting the need for prevention. Surinamese, Antillean and Ghanaian (mainly black) newborns remained unexplainably smaller after adjustment, leaving the possibility of either unknown constitutional or pathological underlying mechanisms.

Does physical activity in leisure time early in pregnancy reduce the incidence of preeclampsia or gestational hypertension

Objective. Assessment of the association of physical activity in leisure time with preeclampsia and gestational hypertension in nulliparous women. Design. Population based prospective cohort study. Setting. Amsterdam, The Netherlands. Population. All pregnant women in Amsterdam between January 2003 and March 2004 who were nulliparous with a singleton pregnancy and who delivered after 24 weeks. Design. At their first prenatal care visit, women were invited to fill out a questionnaire with sociodemographic and psychosocial variables. Physical activity in leisure time in the past week was measured using questions about walking, cycling, playing sports and other activities in leisure time. The amount of minutes and intensity of each activity was studied using four categories: no, low, moderate or high activity. By using multivariate logistic regression, we adjusted for sociodemographic and medical confounders. Main outcome measures. Incidence of preeclampsia and gestational hypertension. Results. A total of 12,377 women were invited with a response rate of 67%; 3,679 nulliparous women were included. The incidence of preeclampsia and gestational hypertension was 3.5% and 4.4%, respectively. The amount of time or intensity of physical activity in leisure time was not associated with a difference in risk of preeclampsia or gestational hypertension. Conclusion. Physical activity in leisure time early in pregnancy does not reduce the incidence of preeclampsia or gestational hypertension in an unselected population of nulliparous women.

Ethnic differences in early pregnancy maternal n-3 and n-6 fatty acid concentrations: an explorative analysis.

Ethnicity-related differences in maternal n-3 and n-6 fatty acid status may be relevant to ethnic disparities in birth outcomes observed worldwide. The present study explored differences in early pregnancy n-3 and n-6 fatty acid composition of maternal plasma phospholipids between Dutch and ethnic minority pregnant women in Amsterdam, the Netherlands, with a focus on the major functional fatty acids EPA (20 : 5n-3), DHA (22 : 6n-3), dihomo-gamma-linolenic acid (DGLA; 20 : 3n-6) and arachidonic acid (AA; 20 : 4n-6). Data were derived from the Amsterdam Born Children and their Development (ABCD) cohort (inclusion January 2003 to March 2004). Compared with Dutch women (n 2443), Surinamese (n 286), Antillean (n 63), Turkish (n 167) and Moroccan (n 241) women had generally lower proportions of n-3 fatty acids (expressed as percentage of total fatty acids) but higher proportions of n-6 fatty acids (general linear model; P < 0.001). Ghanaian women (n 54) had higher proportions of EPA and DHA, but generally lower proportions of n-6 fatty acids (P < 0.001). Differences were most pronounced in Turkish and Ghanaian women, who, by means of a simple questionnaire, reported the lowest and highest fish consumption respectively. Adjustment for fish intake, however, hardly attenuated the differences in relative EPA, DHA, DGLA and AA concentrations between the various ethnic groups. Given the limitations of this observational study, further research into the ethnicity-related differences in maternal n-3 and n-6 fatty acid patterns is warranted, particularly to elucidate the explanatory role of fatty acid intake v. metabolic differences.