It has been hypothesized that B12 may affect placentation and fetal growth ( 8). It is important for the synthesis ( 5) and methylation ( 6) of DNA, and plays a role in the energy production of the cell ( 7). Vitamin B12 (B12) is a vitamin with metabolic roles closely related to folate and homocysteine, and is found in animal-derived foods only ( 4). The etiology of preterm birth, however, is complex, and few interventions have been successful in preventing it ( 3). Globally, preterm birth and low birth weight (LBW) cause over a third of the 2.9 million neonatal deaths each year, and prevention of these events is important to reduce under-five year mortality ( 1, 2). Of vitamin B12 supplementation in pregnancy. This finding supports the conduct of randomized controlled trials Lower maternal B12 in pregnancy increased the risk of Accordingly,ī12-deficiency was associated with increased risk of preterm birth (adjusted RRġ.21 (95% CI 0.99, 1.49). (95% CI 0.82, 0.97) per one standard deviation increase in B12). Maternal levels of B12 and preterm birth (adjusted RR for preterm birth was 0.89 Increased risk of newborn low birth weight (adjusted risk ratio (RR) 1.15 (95%Ĭonfidence interval (CI) 1.01, 1.31)). Linear association was observed between maternal B12 levels in pregnancy andīirth weight, but B12-deficiency (<148 pmol/L) was associated with an Twenty-two eligible studies were identified (11,993 observations).Įighteen studies were included in the meta-analysis (11,216 observations). We performed a systematic review and an individual participantĭata meta-analysis to evaluate the associations between maternal serum or plasmaī12 concentration in pregnancy and offspring birth weight and length of Nevertheless, current evidence isĬontradictory. Vitamin B12 (B12)-deficiency in pregnancy is prevalent, and has beenĪssociated with lower birth weight (birth weight <2,500 g) and pretermīirth (length of gestation <37 weeks).