Low levels of vitamin B12 and folate in fathers, as well as mothers, around the time of conception are linked to a higher risk of birth defects in their children, according to a new study. The research was led by Children's Hospital of Fudan University in Shanghai and published in Annals of Internal Medicine.
Tracking couples before pregnancy
The team recruited couples who planned to become pregnant within a year, drawing from 29 sites across the greater Shanghai area. Researchers measured each parent's vitamin B12 and red blood cell folate levels around conception. They then followed the pregnancies and identified birth defects through prenatal ultrasound, newborn screening for congenital heart disease, delivery records and follow-up imaging. In total, more than 400 birth defects were recorded.
Both parents' levels matter
Higher B12 before conception was tied to lower overall birth-defect risk for mothers and fathers alike. Compared with a maternal B12 level of 221 pmol/L, a value considered low, moderately high levels of 295 pmol/L were linked to 19 percent lower odds of birth defects, and high levels of 443 pmol/L were linked to 38 percent lower odds. The matching estimates for fathers were about 22 percent and 20 percent lower. Folate mattered too, mainly for mothers: women with levels above 340 nmol/L in early pregnancy had a 45 percent lower chance of having a baby with a birth defect than women below that mark.
More than neural tube defects
Folic acid is already known to prevent neural tube defects, and this study suggests the protective role of B12 and folate reaches further. More than half of the defects recorded affected the heart. The authors caution that untested genetic and biological factors could partly explain the results. Still, they say the findings support the idea that both prospective parents should pay attention to their vitamin levels before trying to conceive, and they point to a role for paternal nutrition that has often been overlooked.