In one study, doctors wanted to see if folic acid supplements curbed depression in pregnancy, and measured the diets of 6,809 women at 18 and 32 weeks pregnant.
Although there was no effect on depression during pregnancy or up to eight months after giving birth, women who took folic acid while pregnant were less likely to have depressive symptoms between 8 and 21 months after giving birth compared to women who did not take folic acid during pregnancy.