Plasma homocyst(e)ine concentrations in pregnant and nonpregnant women with controlled folate intake

Objective: To assess the effects of folate intake and pregnancy on plasma total homocyst(e)ine concentrations in women during the second trimester of pregnancy compared with young, healthy nonpregnant women. Methods: The diet provided either 450 or 850 mu g of folate per day. These levels are approximately the current (400 mu g/day) and previous (800 mu g/day) Recommended Dietary Allowances for folate in pregnant women. Folate was provided as both food folate (120 mu g/day) and supplemental folic acid (either 330 or 730 mu g/day) for a period of 12 weeks. Plasma homocyst(e)ine (sum of free and protein-bound homocysteine), serum folate, and erythrocyte folate concentrations were determined weekly. Results: Homocyst(e)ine concentrations were lower in pregnant women during the second trimester of normal pregnancy than in nonpregnant controls, independent of dietary folate intake. The overall mean (+/- standard deviation) homocyst(e)ine concentration of the pregnant subjects (5.4 +/- 1.4 mu mol/L) was significantly lower than that observed in the nonpregnant control group (8.7 +/- 1.7 mu mol/L) (P < .0001). This difference in homocyst(e)ine concentrations remained constant throughout the 12 weeks of the investigation. Conclusion: The folate intakes in this investigation were adequate to maintain constant homocyst(e)ine concentrations in pregnant and nonpregnant women. The lower homocyst(e)ine concentrations observed in pregnant subjects compared with nonpregnant controls may be a physiologic response to pregnancy. (Obstet Gynecol 1998;92:167-70. (C) 1998 by The American College of Obstetricians and Gynecologists.)