A prospective cohort study published in Annals of Internal Medicine found that higher parental vitamin B12 levels before conception and higher maternal red blood cell folate concentrations after conception were associated with a lower risk of birth defects. ^[1] Higher preconception maternal and paternal vitamin B12 levels were associated with a lower predicted prevalence of birth defects among live births, stillbirths, and pregnancies ending because of fetal abnormalities. ^[2] Mothers with adequate red blood cell folate levels in early pregnancy were also found to have a lower predicted prevalence of birth defects. ^[3] Researchers from the Children's Hospital of Fudan University utilized the Shanghai Preconception Cohort to study 3,032 couples who provided blood samples within four months before conception. ^[4] Adequate levels of folate in the mother's red blood cells during early pregnancy were also associated with a reduced risk of congenital disruptions. ^[5] The authors stated that the study was observational and therefore does not prove that increasing Vitamin B12 levels prevents congenital defects. ^[6]