Assessment of vitamin B12 and homocysteine levels in pregnant women admitted for delivery and cord blood samples of their newborn babies: a multicenter study

Background: Vitamin B12, an indispensable micronutrient, is pivotal in numerous physiological processes, with particular significance during pregnancy and fetal development. The increasing adoption of vegetarian diets and the economic challenges associated with accessing animal-based food sources contribute to the prevalence of vitamin B12 deficiency. This study aims to examine the levels of vitamin B12 and homocysteine in pregnant women upon admission for delivery and to analyze corresponding cord blood samples from their newborn infants in a substantial sample within the Istanbul metropolitan area.

Materials and methods: This cross-sectional multicenter study included women aged ≥16 years admitted for delivery and their newborns ≥34 weeks. The demographic data and the results of complete blood counts within the previous 24 hours before birth were recorded. Vitamin B12 and homocysteine levels were measured in maternal and cord blood samples. The study parameters were compared between the groups based on the mothers' and babies' homocysteine and vitamin B12 levels.

Results: The study included 832 pregnant women and 832 neonates. Anemia affected 36% of pregnant women, with a higher frequency in mothers with vitamin B12 deficiency. Seventy-eight mothers and 48.9% of neonates showed Vitamin B12 levels below 200 pg/mL, while elevated homocysteine levels were observed in 30% of mothers and 26% of neonates. Maternal vitamin B12 deficiency was significantly correlated with cord blood B12 deficiency and elevated homocysteine. The median cord blood vitamin B12 level was inversely correlated with the number of previous pregnancies.

Conclusion: Vitamin B12 deficiency is extremely common in pregnant women before delivery, significantly correlating to cord blood homocysteine and vitamin B12 levels. However, homocysteine alone is not a reliable marker for maternal vitamin B12 status. Implementing strategies to detect vitamin B12 deficiency and supplying adequate vitamin B12 supplementation during pregnancy holds the potential to enhance maternal and neonatal health in Türkiye.