Maternal smoking and fetal erythropoietin levels

Objective: To determine the influence of maternal smoking on fetal erythrop oietin concentrations in health term pregnancies and test the correlation b etween cotinine, a biomarker of maternal smoking, and erythropoietin levels in fetuses. Methods: We invited women with healthy term pregnancies to participate in t he study, excluding those with conditions previously known to be associated with elevated fetal erythropoietin levels. We recorded demographic data, s moking status, and labor outcome prospectively for each patient. Umbilical venous samples were collected, and serum was stored at -70C to be analyzed later for erythropoietin and cotinine. Umbilical arterial samples were test ed for pH and base excess determination. We compared fetal erythropoietin a nd cotinine between smokers and nonsmokers and examined correlations betwee n erythropoietin and cotinine. Kruskal-Wallis test, t test, median test, an d Spearman rank correlation test were used when appropriate. Statistical si gnificance was P < .05. Results: We recruited 35 nonsmokers and 26 smokers and analyzed their sampl es. The two groups were comparable in demographics and birth outcomes, exce pt for birth weights, which were lower in smokers. Fetal erythropoietin con centrations increased significantly with increasing maternal cigarette cons umption, ranging from none to more than 15 cigarettes per day (P = .03). Th ere was positive correlation between fetal erythropoietin and cotinine conc entrations (r = .41; P = .04), suggesting a dose-response relationship. Conclusion: Fetuses of smokers had increased erythropoietin concentrations that correlate positively with fetal cotinine levels; which suggests an inc reased risk of subacute hypoxia related to degree of maternal cigarette con sumption. (C) 2000 by The American College of Obstetricians and Gynecologis ts.