Higher vitamin B12 levels in both parents are associated with lower risk of birth defects

A prospective cohort study quantifying the associations of parental vitamin B12 and red blood cell (RBC) folate with birth defects found that higher parental vitamin B12 before conception and higher maternal RBC folate concentrations after conception were associated with lower birth defect risk.

The findings suggest that the nutritional status of both parents around the time of conception may play a role in preventing birth defects. The study is published in Annals of Internal Medicine.

Researchers from the Children's Hospital of Fudan University and colleagues used the Shanghai Preconception Cohort to study 3,032 couples who provided blood samples within 4 months before conception and 17,765 women who were tested at 4 months’ gestation or earlier.

The researchers measured vitamin B12 and folate levels and examined their relationship with birth defects identified among live births, stillbirths, and pregnancies ending because of fetal abnormalities.

They found that higher preconception maternal and paternal vitamin B12 levels were associated with lower predicted prevalence of birth defects, and that mothers with adequate RBC folate levels in early pregnancy also had lower predicted prevalence of birth defects.

According to the authors, these findings support the potential importance of both paternal and maternal nutrition during the periconceptional period and early pregnancy.

Reference:

Hongyan Chen, Xiaotian Chen, Yi Zhang, et al. Periconception Parental Red Blood Cell Folate, Vitamin B12, and Birth Defects in Offspring: A Prospective Cohort Study. Ann Intern Med. [Epub 1 September 2026]. doi:10.7326/ANNALS-25-05243