The study included close to 40,000 children participating in the Norwegian Mother and Child Cohort Study (MoBa) at the Norwegian Institute of Public Health (NIPH).
"This is the first study of its kind to investigate maternal use of folic acid in the period before and after conception and language delay. There have been no previous studies of so many women with such detailed information about dietary supplement use before and during pregnancy. The MoBa study is unique in this context and the present study would not have been possible without the large number of participants and the detailed information they contribute," said Christine Roth from the Division of Mental Health at the NIPH.
This study was published in the Journal of the American Medical Association (JAMA). Considering that this study is the first to investigate the association between periconceptional folic acid use and severe language delay at age three, caution should be taken about drawing conclusions before further studies have been conducted in other samples in other countries.
Recommended to take a folic acid supplement
It has long been known that folate supplements early in pregnancy reduce the risk for neural tube defects, e.g. spina bifida. The Norwegian Directorate of Health recommends that women who are planning to conceive should take supplements of the B vitamin.
Folate and severe language delay
The results from this study suggest that adequate levels of folate are not only important for the prevention of neural tube defects, but possibly also for other aspects of neurodevelopment.
In this study, children of mothers who took folic acid in the period four weeks before conception to eight weeks after conception had a significantly reduced risk of having a severe language delay at the age of three. This association should be further investigated in other population-based studies.
Folate is a water-soluble B-vitamin and our main food source is from leafy green vegetables such as broccoli or spinach.
It is important to note that the range for reaching certain milestones in young children is quite wide and that language delay can be associated with other factors such as having hearing problems or a neurodevelopmental disorder.
About the study
The closure of the spinal cord in the foetus occurs by the fourth week of pregnancy. Deviations in this early development can lead to malformations of the spinal cord and brain. In the most severe cases the foetus does not develop a brain at all (anencephalus) while in other instances the foetus can have more or less disabling malformations of the spinal cord (spina bifida). In this study we focused specifically on those children that were rated as having severe language delay by maternal report at the age of three. Severe language delay is quite rare and only 0.5 per cent of the children had not started to combine words into sentences at the age of three.
In this study we found that children of mothers who used folic acid in the period four weeks before to eight weeks after conception had half the risk of having severe language delay at age three, compared to children of mothers who took no folic acid in this period. We did not find any protective effect of folic acid use on motor development. For children of women who took other vitamins without folic acid in the same period, we observed no reduced risk of severe language delay. Furthermore, we did not observe any reduction in risk for children of mothers who began taking a folic acid supplement after week eight of pregnancy. We do however caution that the number of women that started after week eight was small.
The findings from this study are potentially important for our understanding of the factors that influence the brain’s early development. However, we still have to be mindful of potential weaknesses of the study and keep on searching for other causes of language delay. Only further research can elucidate the role of folic acid. The findings from this study add to the recommendations from the Norwegian Directorate of Health that encourages women of childbearing age to initiate folic acid supplements before they conceive.
Several researchers from the Norwegian Institute of Public Health have been involved in this study. From the Division of Mental Health: Christine Roth (lead author), Synnve Schjølberg and Ted Reichborn-Kjennerud. From the Division of Epidemiology: Per Magnus (P.I.), Camilla Stoltenberg and Pål Suren. Christine Roth has spent part of her doctoral training at Columbia University with senior author Ezra Susser, Division of Epidemiology, the Mailman School of Public Health as her mentor.
Folic Acid Supplements in Pregnancy and Severe Language Delay in Children. C Roth, P Magnus, S Schjølberg, C Stoltenberg, P Surén, IW McKeague, G Davey Smith, T Reichborn-Kjennerud, E Susser, JAMA. 2011;306(14):1566-1573