Periconception vitamin B12, RBC folate tied to low prevalence of birth defects

Periconception parental vitamin B12 and postconception maternal red blood cell (RBC) folate are predictive of lower birth defect prevalence, suggests a study.

A total of 3,032 couples (73 birth defect cases) with biomarkers sampled within 4 months before conception and 17,765 women (327 birth defect cases) sampled at 4 months’ gestation or earlier were included in this prospective cohort study in China.

The authors used weighted logistic regression to estimate standardized predicted prevalences of birth defects ascertained among live births, stillbirths, and abortions due to foetal abnormalities.

Dose-response analyses revealed an association between higher preconception parental levels of vitamin B12 and reduced predicted prevalences of birth defects.

For preconception maternal vitamin B12 from the lowest (<148 pmol/L) to highest (≥590 pmol/L) categories, a substantial reduction in predicted prevalence was observed, from 49.6 to 16.2 cases per 1,000 pregnancies. This pattern was also seen in paternal vitamin B12, with a decrease from 55.5 to 24.0 cases per 1,000 pregnancies.

For preconception parental RBC folate, patterns of lower predicted prevalence were unclear. Postconception maternal RBC folate showed lower predicted prevalence at levels of 906 to 1,131 nmol/L than levels <453 nmol/L (16.5 vs 25.7 cases per 1,000 pregnancies), with little further decrease at higher levels.

For postconception maternal vitamin B12, predicted prevalence showed minimal changes across lower categories but was lower at higher levels (11.8 vs 20.4 cases per 1,000 pregnancies at ≥590 vs 148‒294 pmol/L, respectively).

“Maternal folic acid prevents neural tube defects, but associations of parental folate and vitamin B₁₂ with birth defects remain unclear,” the authors said.