Beyond Folate: The Emerging Role of Maternal Vitamin B12 in Neural Tube Development.

Folic acid (FA) supplementation can effectively reduce the occurrence of neural tube defects (NTDs). Vitamin B12 is involved in folate metabolism; however, studies have not reached a definitive conclusion on the association between vitamin B12 and NTDs independent of folate levels. A systematic review and meta-analysis were performed to summarize existing research and investigate the effect of vitamin B12 on NTDs. Studies were systematically searched in PubMed, Web of Science, Embase, and Cochrane, published before 1 March 2024. Standardized mean difference (SMD) with 95% confidence interval (CI) was employed to assess the association between maternal vitamin B12 in blood and NTDs. A total of 38 studies were included, with a total of 2316 NTDs and 4298 controls, covering 14 countries worldwide. Compared with the non-NTD group, the NTD group exhibited a lower vitamin B12 level [SMD = -0.23, 95% CI (-0.32, -0.14), < 0.001, = 58.3%] with a statistically significant difference. Additionally, there was a significant association between maternal vitamin B12 concentration and NTDs when there was no significant difference in folate between the NTD and control groups [SMD: -0.19, 95% CI (-0.28, -0.10)]. Vitamin B12 supplement is also essential for the prevention of NTDs besides folic acid. Monitoring vitamin B12 concentration among pregnant women and considering appropriate supplementation with a combination of vitamin B12 and folic acid could be explored.