Abstract 6272: Smoking Cessation Early in Pregnancy and Birth Weight, Length, Head Circumference, and Endothelial Nitric Oxide Synthase Activity in Umbilical and Chorionic Vessels. An Observational Study of Healthy, Singleton Pregnancies
Background - Reduced production of the vasodilator nitric oxide (NO) in fetal vessels in pregnant smokers may lower the blood flow to the fetus and result in lower birth weight, length, and head circumference. The present study measured endothelial NO synthase (eNOS) activity in fetal umbilical and chorionic vessels from non-smokers, smokers, and ex-smokers, and related the findings to the fetal outcome.
Methods and Results - Of 266 healthy, singleton pregnancies; 182 were non-smokers, 43 were smokers, and 41 stopped smoking early in pregnancy. The eNOS activity and concentration were quantified in endothelial cells of the fetal vessels. Cotinine, lipid profiles, estradiol, L-arginine, and dimethylarginines that may affect NO production were determined in maternal and fetal blood. Serum cotinine verified self-reported smoking. Newborns of smokers had a lower weight (P≤0.001), smaller head circumference (P≤0.041), and were shorter (P≤0.001) than were newborns of non-smokers and ex-smokers. The eNOS activity in umbilical veins of smokers was 36% lower (P<0.001), the eNOS concentration 47% lower (P<0.001), and the fetal plasma level of high density lipoprotein 11% lower (P=0.008) than that of non-smokers, while the same levels were found in umbilical veins from ex-smokers and non-smokers. The same pattern in eNOS activity and concentration was found in umbilical arteries and chorionic vessels. Fetal plasma levels of estradiol, L-arginine, dimethylarginines, total cholesterol, and triglyceride were similar for non-smokers, smokers, and ex-smokers.
Conclusions - The findings suggest that maternal smoking reduces eNOS activity in the fetal vascular bed, contributing to retarded fetal growth caused by the reduction of vasodilatory capacity and that smoking cessation early in pregnancy prevents these effects in the newborns.