While the human brain continues develop throughout the first twenty or so years of life, the most vulnerable periods of brain development occur during pregnancy and the first 2 to 3 years of the child’s life, when there is rapid brain growth. Various studies have demonstrated that women exposed to famine during pregnancy have an increased risk of having a child with psychiatric illness. We also know that deficiencies of certain nutrients during critical phases of brain development may result in irreversible changes to the brain. While this research supports a link between maternal nutritional status and children’s neurodevelopment, we know much less about the impact of less extreme nutritional deficits.
Animal studies have demonstrated that a maternal “western” diet, high in fats and sugars, and maternal obesity may affect the fetus: rodent offspring born to these mothers exhibit increased sympathetic nervous system activity and hyperactivity, changes which persist into adulthood. Other studies indicate that deficiencies in omega-3 fatty acids during in utero development and early life reduce brain plasticity and increase anxiety-like behaviors in adult mice. These animal studies suggest a causal relationship between maternal dietary exposures and behavioral outcomes in their offspring; however, we are just beginning to study the impact of maternal diet on the human fetus.
Over the last few years, evidence has been generated to indicate that dietary habits may modulate the risk for depression and anxiety in both adults and adolescents. It is not clear, however, if very early life nutritional exposures may also influence a child’s subsequent vulnerability to psychiatric illness. Two recent studies yield data supporting a link between maternal diet in pregnancy and outcomes in children.
Norwegian Mother and Child Cohort Study (MoBa)
In this prospective cohort study, pregnant women were recruited, and data was collected from 23,020 mothers during pregnancy and at 4 later time points (6 months and 1.5, 3, and 5 years). Adjustments were made to account for potential confounding factors including sex of the child, maternal depression, maternal and paternal age, maternal education, household income, maternal smoking before and during pregnancy, and marital status.
The researchers found that higher intake of unhealthy foods (processed foods, refined cereals, sweetened drinks, and high calorie snacks and desserts) during pregnancy predicted externalizing behaviors (e.g., aggression) among their children. This association persisted after controlling for confounding factors, including maternal depression and the child’s dietary habits. Children with diets high in unhealthy foods and/or diets low in nutrient-dense foods, such as vegetables, exhibited higher levels of both internalizing and externalizing problems.
Avon Longitudinal Study of Parents and Children (ALSPAC)
The second study examined the link between maternal diet and children’s cognitive functioning at 8 years of age. 6979 mother-offspring pairs participating in the Avon Longitudinal Study of Parents and Children (ALSPAC) in the United Kingdom were assessed. Maternal reports of diet were assessed at 32 weeks of gestation and at 4 years postpartum. Maternal depressive symptoms were assessed five times between 18 weeks of gestation and 3 years postpartum. Children’s cognitive functioning was assessed at age 8 years.
During pregnancy, mothers who reported higher levels of depressive symptoms were more likely to consume diets higher in unhealthy foods (i.e., fats, sugars, processed foods) and/or diets lower in nutrient-rich foods, such as vegetables and whole grains. Lower levels of healthy nutrition and higher levels of unhealthy nutrition were both associated with reduced cognitive functioning at age 8. These results persisted after controlling for a variety of potential confounding factors, including maternal depression, poverty, younger age, low maternal education, parity, birth complications, and substance use.
The Take-Home Message
Undoubtedly the relationship between maternal diet and child outcomes is quite complicated. While these studies have focused on diet and attempted to control for confounding factors, such as maternal depression, it is possible that there are other genetic variables and/or lifestyle factors involved that are much more difficult to identify and assess. Combining these two studies with what is already known, we can make the following comments:
- Women with depressive symptoms are more likely to consume diets higher in unhealthy foods (i.e., fats, sugars, processed foods) and lower in nutrient-rich foods.
- Consuming a diet higher in unhealthy foods during pregnancy may increase the vulnerability to later behavioral and cognitive problems in children.
- Young children consuming a diet high in unhealthy foods, and/or a diet low in nutrient-dense foods exhibit more behavioral problems.
These data suggest that we need to better educate women about the potential negative effects of unhealthy diets on the unborn child and to provide information about nutrition during pregnancy. Women who are pregnant or planning pregnancy are often highly motivated and able to make significant changes in their lifestyle – such as quitting smoking or abstaining from alcohol — for the sake of their pregnancy. This may be a window of opportunity where women are more likely to adopt healthier patterns of eating which persist beyond the pregnancy.
Ruta Nonacs, MD PhD
Barker ED, Kirkham N, Ng J, Jensen SK. Prenatal maternal depression symptoms and nutrition, and child cognitivefunction. Br J Psychiatry. 2013 Dec;203(6):417-21.
Jacka FN, Ystrom E, Brantsaeter AL, et al. Maternal and Early Postnatal Nutrition and Mental Health of Offspring by Age 5 Years: A Prospective Cohort Study. J Am Acad Child Adolesc Psychiatry. 2013; 52(10):1038-47