Background: The timing of folic acid supplement usage is critical to preventing pregnancies affected by neural tube defects (NTDs) because the neural tube closes by Day 28 post-conception. We investigated compliance of pregnant women with current folic acid recommendations (400 µg/day from preconception to 12 weeks) in relation to achieving a folate status associated with lowest risk of NTDs.
Methods: From a sample of 296 women with singleton uncomplicated pregnancies attending an antenatal clinic in Northern Ireland, those who reported taking folic acid in the first trimester (n = 226) were investigated. Samples were taken at 14 weeks gestation to measure serum concentrations of folate and vitamin B12 (related to folate and an independent predictor of NTD), and dietary B-vitamin intake and folic acid usage were investigated.
Results: Although the majority of the overall sample (84%) reported taking folic acid supplements in the first trimester, only 19% had started before conception, as recommended. Multigravidae compared with primigravidae women were less likely to have followed the recommendations correctly (P= 0.001). At 14 weeks, red cell folate (considered a reliable biomarker of previous 3 months, covering time of neural tube closure) was correlated (r = 0.320, P < 0.001) with the reported duration of folic acid usage, and was lower (P< 0.0001) in women who started folic acid after conception.
Conclusions: Red cell folate concentrations in women not complying with recommendations were suboptimal in relation to NTD risk. The findings generally support the recent official recommendation to the Chief Medical Officer for mandatory fortification of food with folic acid in the UK.