After delivery of the fetus and placenta, women with pregnancy-induced megaloblastic anemia due to folate deficiency responded to the administration of as little as 50μg of folic acid per day while they were receiving a low folate diet. The presence of a fetus and placenta increased the amount of folic acid necessary to induce a comparable hematological response to 0.5 mg/day or somewhat more. One milligram of folic acid uniformly produced a satisfactory hematological response prior to delivery even when pregnancy requirements were augmented further by twin fetuses or chronic hemolysis. Consequently, daily supplementation with 1 mg of folic acid during pregnancy should protect all pregnant women against folate deficiency including those with multiple fetuses, chronic hemolysis, and repetitive megaloblastic anemia.
Pritchard JA, Scott DE, Whalley PJ. Folic Acid Requirements in Pregnancy-Induced Megaloblastic Anemia. JAMA. 1969;208(7):1163-1167. doi:10.1001/jama.1969.03160070041010