The ABCD study studies a wide range of risk factors during and around pregnancy that may play a role in child development and health at birth and later in life. We are also investigating whether there are ethnic differences in lifestyle during pregnancy, in birth outcomes, and in child health later in life. Below is a description of some of our results, published in international scientific journals. An overview of all publications can be found in the publications list.
Nutrition
An important area of research within the ABCD study focuses on the risk factor ‘nutrition’.
Our research shows that low folate intake, low vitamin D status and an unfavourable fatty acid profile (relatively high omega-6 fatty acids and relatively low omega-3 fatty acids) during pregnancy increase the risk of a low birth weight child. Women of non-Dutch origin are more likely to have an unfavourable fatty acid profile, low vitamin D status ,and low folate intake.
Research has also found that mothers with low vitamin B12 status during pregnancy were more likely to have babies with extreme crying behaviour. This link is possibly explained by vitamin B12’s influence on sleep-wake rhythms.
Naturally, a mother’s nutritional status can also affect her own health. For instance, within the ABCD study, we also investigated whether low vitamin D status was associated with more depressive symptoms during pregnancy. Our study found that mothers with low vitamin D status were also more likely to have depressive symptoms. Vitamin D has many functions in the body, and it is becoming increasingly clear that vitamin D is also important for mental health. Of course, whether higher vitamin D intake can actually reduce or even prevent depressive symptoms needs further research.
In addition, upbringing plays an important role in a child’s diet. Not only that of the mother, but also that of the father. If the father eats healthily, this mainly affects their sons’ healthy diet. Children also drink a lot of sweet drinks: as early as 5/6 years of age, an average of 4 glasses a day. This is unfavourable for blood pressure 5 years later.
Ethnic differences in health
Within the ABCD study, we explicitly investigate health differences between population groups. We investigate whether there are differences in lifestyle during pregnancy, in birth outcomes, and in child development and health later in life.
So far, the ABCD study shows that women of Surinamese, Antillean, and Ghanaian descent are more likely to have a premature child or child with low birthweight than women of Dutch descent. There are also ethnic differences regarding eantrance of pregnant women into care, consumption of folic acid supplements, and thyroid functioning. It appears that some of the differences in pregnancy outcomes can be explained by the above factors and other known risk factors, such as smoking. Obesity already before pregnancy results in an increased risk of preterm birth and an oversized baby. This increased risk applies to all pregnant women. However, obesity is much more common in immigrant pregnant women, making it a bigger problem in this group.
Growth and health
Babies of non-western origin grow faster in weight and height during the first six months of life compared to native babies. Differences in feeding patterns are also visible. For instance, Turkish mothers breastfeed longer and Moroccan mothers more often combine breast and bottle feeding compared to native mothers. Mothers of African descent breastfeed for a shorter time and start solid food feeding earlier. Also at age 5, children of Turkish and Moroccan descent are more often overweight. Turkish children are also more likely to have elevated blood pressure, glucose and triglyceride levels (cardiometabolic profile). This is mainly because the children are more often overweight. Moroccan children, on the other hand, have a favourable cardiometabolic profile despite being more often overweight. Children from low socioeconomic environments also have a worse cardiometabolic profile than children from high socioeconomic environments. This is mainly because their mothers smoke more during pregnancy and are heavier. And also because the children themselves have a lower birth weight and grow faster afterwards, probably because they are breastfed for less time.
Furthermore, it appears that the accompanying role of parents is important in the prevention of childhood obesity. ‘Seeing’ and recognising obesity is crucial in this regard. Results of our study showed that in 5-year-old children, overweight is often not recognised by mothers. This is true for native mothers, but even more so for Turkish and Moroccan mothers. Education, culture, and age of the mother play an important role in recognising their child’s obesity.
Psychosocial stress
Psychosocial stress during pregnancy is a risk factor that receives a lot of attention in the ABCD study. When women experience a lot of (work) stress during pregnancy, are very anxious, or often feel gloomy, this can affect their child’s physical health and behavioural development.
Almost 30% of pregnant women report having depressive feelings during pregnancy. This percentage is higher among women of Turkish, Moroccan, and African descent.
Anxiety and depressive feelings are related to smoking during pregnancy, but not to gestational hypertension or diabetes. High work stress combined with working more than 32 hours early in pregnancy is more likely to result in a low birth weight child.
Physical health
Pregnant women who suffered from depressive symptoms had a shorter gestational age and, as a result, had babies with lower birth weight. The combination of depressive symptoms and low levels of folate (vitamin B9) in the blood (a combination found in 7.6% of pregnant women) was linked to a shortening of gestational age by an average of 2.8 days. Depression and low vitamin intake often go hand in hand, but the effects they have on birth outcomes are independent of each other.
Psychosocial stress, such as anxiety, depression, and work stress during pregnancy, does not lead to obesity at 5 years of age. However, high levels of stress can lead to higher blood pressure in the child. In addition, children of mothers who are very anxious during pregnancy are more likely to have behavioural problems (hyperactivity, emotional problems). They also perform less well on a reaction time task than children of mothers who are less anxious. Boys in particular were found to be susceptible to this. Furthermore, various forms of psychosocial stress in the pregnant woman were not associated with the functioning of the autonomic nervous system at rest (including less variation in heart rate frequency; a risk factor for having a heart attack later in life) in the 5-6-year-old child.
Results showed that work stress, a combination of high workload with little opportunities for regulation (experiencing control over tasks), affects the child’s birth weight. For example, pregnant women who experience high work stress combined with a long working week are twice as likely to have an underweight child.
Cognition and behaviour
Five- to six-year-old children of mothers who were very anxious during pregnancy performed less well on a task that tested their reaction speed. Especially when the task became more complicated, children of anxious mothers performed less well. Boys with anxious mothers were found to have more difficulty, even with the simple task, than girls with anxious mothers. High levels of anxiety during pregnancy additionally affected the behaviour of preschoolers. Children of mothers who were very anxious during pregnancy have more behavioural problems at the age of five. These children are more often described as ‘busy’ by their mothers, and mothers also report more often that these children have difficulty staying focused. Children of very anxious mothers are also more likely to have emotional problems and problems in interacting with peers. Furthermore, our research shows that boys have more problems with attention and hyperactivity compared to girls. Children with behavioural problems at age five to six have an unfavourable cardiometabolic profile 5 years later. This is mainly explained by lifestyle factors such as more screen time.