Folate levels in pregnant women who smoke: an important gene/environment interaction.

Objective: The objective of this study was to determine whether serum and red blood cell folate levels were decreased in pregnant women who smoke and whether total plasma homocysteine levels were elevated.

Study Design: In this cross-sectional study, serum folate, red blood cell folate, and homocysteine were measured in pregnant first- and early second-trimester pregnant women who smoked (case subjects) and pregnant women who did not smoke (control subjects). In addition, vitamin B(12), albumin, creatinine, cotinine, and hematocrit levels and methylenetetrahydrofolate reductase status were determined and compared between groups.