First-trimester serum folate levels and subsequent risk of abortion and preterm birth among Japanese women with singleton pregnancies

To determine whether a low serum folate level during the first trimester predicts subsequent late abortion, preterm birth, or fetal growth restriction (FGR). A prospective cohort study involving 5,075 women whose serum folate levels were measured during the first trimester. The participants were informed of their serum folate levels. The pregnancy duration, birthweight, rate of late abortion/preterm birth, and the rate of FGR did not differ significantly among the four groups classified according to folate status. The mean serum folate levels did not differ among quartiles classified according to the gestational week at the time of delivery. Nineteen of the 20 women with folate deficiency gave birth at term to infants with a birthweight of 3.132 +/- A 321 g; only one infant had FGR. Low serum folate levels during the first trimester were not associated with the risk of late abortion, preterm birth, or FGR.