Blackmores Institute

Conducting a prospective study using data from the nationwide, population-based Medical Birth Registry of Norway (MBRN) found the use of folic acid and/or multivitamin supplements before and during pregnancy was associated with a small reduction in the risk of total birth defects among live births and stillbirths. 
 
 The study investigated the prevalence of birth defects among all births, including live births, stillbirths and termination of pregnancies due to foetal anomaly (TOPFA) and compared the risks of organ-specific major birth defects in live and stillborn infants of mothers who did or did not use folic acid and/or multivitamin supplements during the period 1999–2013.
 
 “The present study included eleven major non-chromosomal birth defect groups in the entire birth population of Norway during 1999–2013. The study found that folic acid and/or multivitamin supplement use before and during pregnancy was associated with a slight reduction in risk of infant total birth defects among live- and stillborn babies (aRR 0·94, 95 % CI 0·91, 0·98). The reduced risk was observed for birth defects in the abdominal wall, genital organs and limbs. Protective associations were also suggested for neural tube defects (NTD), respiratory system defects and digestive system defects although CI included the null value of 1. 
 
 According to the study, the exact mechanism of why folic acid supplementation prevents NTD or other birth defects is not known, but associations have been established with erythrocyte folate concentration, suggesting that women below the cut-off for what is considered optimal erythrocyte are thought to have elevated risk of having babies with NTD. Functioning as a coenzyme in one-carbon metabolism during the methylation cycle, folate is crucial for DNA synthesis, and during pregnancy, there are higher rates of one-carbon transfer reactions.
 
 Noting that the randomised controlled trials on NTD were specific to folic acid, the authors explained that less bioavailable dietary folate means that consumption of dietary folates is considered to result in a significantly smaller increase in erythrocyte folate concentration than folic acid.
 
 “Since food fortification with folic acid is not mandatory in Norway, the prevention strategy with a supplementation programme requires a high proportion of planned pregnancies and high compliance with the programme. Many Norwegian women are not aware of the importance of supplementation before pregnancy and have diets that do not meet the recommendations,” the authors explained.
 
 With the study findings suggesting that some birth defects may be prevented by maternal use of folic acid or multivitamins, the authors pointed out that the extent of the risk reduction differs for the different types of birth defects and type of exposure (multivitamin or folic acid). 
 
 “Better definitions of the exposures regarding specific supplement types, timing and dosage would be beneficial in understanding the different roles of specific micronutrients in the aetiology of birth defects. Since our study suggests that folic acid or multivitamin supplementation could have protective associations for other birth defects besides NTD, the prevention potential may be larger than anticipated,” the authors concluded.
 
 “Use of folic acid and/or multivitamin supplements before and during pregnancy was associated with a small reduction in the risk of total birth defects among live births and stillbirths. More specifically, the risk reduction was observed for abdominal wall defects, genital defects and limb defects,” the authors concluded.
 
 Source:
 Br J Nutr. 2020. DOI: <a href="https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/maternal-use-of-folic-acid-and-multivitamin-supplements-and-infant-risk-of-birth-defects-in-norway-19992013/E60885CA3B2386F35307A131D1215E0B ">10.1017/S0007114520001178</a>.

The benefits of folic acid to infants may extend beyond the prevention of neural tube defects according to results of a Norwegian study published in the British Journal of Nutrition.

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