[The effect of tobacco smoking on nitric oxide serum concentration in pregnant women and umbilical cord blood].

The aim of the study was to estimate the effect of tobacco smoking on serum nitric oxide (NO) concentration in pregnant women and umbilical cord blood and birth weight. We also examined the relation between serum NO and number of cigarettes consumed by mother. Forty healthy pregnant women patients of Clinical Department of Obstetrics and Gynecology, Institute of Mother and Child were divided into two groups: smoking and tobacco abstinent according to questionnaire declaration. The current smokers were defined as those who had smoked 5 cigarettes per day for 2 years before conception and continued smoking during pregnancy. Serum concentrations of nitric oxide were determined by colorimetric method using a commercially available kit Nitric Oxide NonEnzymatic Assay (Oxis International Inc, USA). We observed that the mean concentrations of nitric oxide in serum were similar on the beginning and the end of pregnancy. In group of smoking women these values decreased during pregnancy and were lower 10% in I and 20% in III trimester (p < 0.01) than in tobacco abstinent. In umbilical cord blood of infants born to smoking women level of nitric oxide was slightly lower than in non-smoking ones. In both studied groups the mean concentrations of nitric oxide in umbilical cord blood were higher than these observed in mothers in third trimester (in smoking 46% and in nonsmoking 17% respectively; p < 0.01). In smoking group we observed positive correlation between concentrations of NO in serum of mothers and cord blood of their newborns (r = 0.74; p < 0.01). Our analysis revealed negative correlation between number of cigarettes consumed and serum nitric oxide in smoking women (r = -0.52 in I trimester and r = -0.47; p < 0.05 in III trimester) as well as in their children (r = - 0.35; p < 0.05). Birth weight in infants born of smoking mothers was lower in average by 260 g as compared with non-smoking ones (p < 0.05). Our results indicate that tobacco smoking during pregnancy reduced serum nitric oxide concentrations in mothers and their children and correlated with number of cigarettes daily consumed. In smoking women lower concentrations of NO co-exist with smaller birth weight than in tobacco abstinent which may suggest correlation between these parameters. Further studies will be continued in larger group of matched maternal-cord pairs to confirm of this association.