Vicente Martínez-Vizcaíno, Celia Álvarez-Bueno and Iván Cavero-Redondo
Our study, recently published in the IJE, looks at the relationship between pre-gestational weight status and children’s neurodevelopment. It shows that children born to mothers who were normal weight before pregnancy scored better on cognition tests than children born to obese women. An original aspect of our study is that it summarises the evidence provided by 15 previous follow-up studies, including samples from seven different countries, and provides information for both cognition tests and general intelligence scores.
We were interested in this issue because rates of overweight and obesity have reached epidemic dimensions in recent years, affecting all populations and stages of life, including women of reproductive age. Maternal overweight and obesity have previously been related to negative outcomes — for both mothers and children — that could be tracked later in life. In this regard, pregnancy is a critical period in brain development and the factors that could affect its development should be cautiously studied.
Our study, which included 42 735 children aged from 6 months to 14 years, contributes to the research on the relationship between a mother’s weight status and her children’s outcomes. We analysed all the data we could find regarding cognition scales, including information on different domains of cognition (ie, verbal skills, reasoning, memory, mental processing). We also analysed the isolated possible effect of a mother’s weight status on children’s general intelligence. We found that obesity in mothers before pregnancy could negatively affect children’s neurodevelopment, and these effects could be observed independently of children’s age. However, it seems that mothers being overweight before pregnancy is not related to children’s neurodevelopment.
Even though these effects were small and could not be expressed in terms of children’s general intelligence, they should be carefully considered. The prevalence of obesity among women of childbearing age is continually rising, and we should not forget that gestation is a critical period in children’s development.
It has been reported that excess of maternal weight before pregnancy increases the risk of offspring suffering several disorders, such as attention deficit hyperactivity, eating and psychotic disorders, or motor development disorders. The growth of brain structures is a continuous process from conception to adulthood, in such a way that children’s brain maturation requires a sensitive environment, which is susceptible to be modified by several factors, including some obesity-related physiological factors in mothers (ie, inflammatory markers). Gestational complications that are more common among obese mothers (ie, gestational diabetes mellitus, pre-eclampsia or iatrogenic preterm delivery) could also be behind this relationship.
The most important implication of this study is that it quantifies the possible effect of maternal pre-pregnancy excess weight on children’s neurodevelopment. Excess weight could be associated not only with women’s cardiometabolic diseases, cancer or reproductive disorders, it could also affect the offspring’s health and cognitive skills. To mitigate the risk of future health cognition problems in childhood, it may be advisable to implement interventions aimed at preventing overweight and obesity in all women of childbearing age and particularly those who are planning a pregnancy. Strategies to combat excess weight, such as physical activity interventions, have shown positive effects on reducing weight status and influencing other outcomes in both mothers (type of delivery, postpartum depression, gestational diabetes) and children (Apgar score, birth weight).
This study is only one piece in the research into the effects of mothers’ weight status, and further research is needed to elucidate questions that remain unanswered, such as the relationship of a mother’s weight status to her children’s appetite or metabolic syndrome later in life. The possible moderating effect of variables that could modify this relationship (socioeconomic level, gestational diabetes or hypertension) should also be explored. A note of caution about our data: we found a small effect of a mother’s weight status on her children’s cognition, and this is a complex relationship that could be influenced by many aspects. In that sense, we would like to know how these findings could vary, considering important factors as parental education, maternal depression or children’s birthweight. Additionally, the studies did not show consensus regarding the scale used for cognition assessment, and this could be an important point that might affect these results.
Álvarez-Bueno C, Cavero-Redondo I, Lucas-de la Cruz L, et al. Association between pre-pregnancy overweight and obesity and children’s neurocognitive development: a systematic review and meta-analysis of observational studies. International Journal of Epidemiology 2017. doi: https://doi.org/10.1093/ije/dyx122.
Vicente Martinez-Vizcaino is the Head of the Health and Social Research Center in the University of Castilla-La Mancha, Spain. He is an epidemiologist interested in the effects of exercise in health. He is the Principal Investigator of a cluster randomized controlled trial aimed at determining the effects of an after-school physical activity program on children’s fitness-related health conditions (health-related quality of life, academic achievement and cardiovascular health) that has been developing for 10 years (MOVIKids). He is a member of the Spanish Society of Epidemiology and Public Health.
Celia Álvarez-Bueno is a Training University Professor research fellow in the University of Castilla-La Mancha. She has an active clinical background as a nurse and physiotherapist. Her research focuses on children’s cognition and how it could be improved by incorporating healthy behaviour, such as participation in physical activity programs.
Iván Cavero-Redondo is a Training University Professor research fellow in the University of Castilla-La Mancha. His research is focused on the epidemiology of cardiometabolic risk, especially on predictors of diabetes complications, such as HbA1c, and in studying how physical activity can control cardiovascular parameters to prevent the risk of further complications.