Vitamin B12 (B12) sufficiency during pregnancy is essential for optimal maternal health and fetal and infant growth and development. Maternal B12 deficiency has been associated with poor pregnancy outcomes, such as preterm birth, low birth weight, intra-uterine growth restriction and neural tube defects, as well as poor cardiometabolic health and impaired cognitive development in the infant. Suboptimal B12 status has previously been reported in pregnant Canadian women. A secondary analysis study conducted by the research team of Dr Yvonne Lamers, Canada Research Chair in Human Nutrition and Vitamin Metabolism, aimed to determine B12 status and the prevalence of B12 deficiency in pregnant women in Metro Vancouver, using the more sensitive, combined measurement of a direct (plasma total B12) and functional (methylmalonic acid (MMA)) B12 indicator. The sample of the original cross-sectional study included 320 women with singleton pregnancies between their 20th and 35th weeks of gestation, with data collection between February 2009 and February 2010.
The prevalence of plasma total B12 concentration below 148pmol/L (reflecting B12 deficiency) and of concentrations between 148-220pmol/L (reflecting suboptimal B12 status) were 18% and 33%, respectively, in these 320 pregnant women of European, Chinese Asian, South Asian or other ethnicities. South Asian ethnicity was the strongest predictor of having plasma total B12 concentration reflecting B12 deficiency, with South Asian pregnant women having a 10x greater risk of B12 deficiency compared to European pregnant women. The odds of having elevated MMA concentrations (>220pmol/L) was 5x higher in South Asian compared to European pregnant women. Conversely, B12 supplement use decreased the risk of B12 deficiency by 69% in all pregnant women. A higher prevalence of B12 deficiency in South Asian pregnant women may be due to lower intake of animal source foods, the natural sources of dietary B12. Future research is underway to investigate the predictors of low B12 status in South Asian pregnant women. Overall, the study highlights the importance of determining B12 status early in pregnancy to allow for early intervention to prevent adverse maternal and fetal health outcomes.
Read the full study here.