PURPOSE: the study the effects of maternal cigarette smoking during pregnancy on placental maturation (calcifications) and the placental-uterine circulation, evaluated through umbilical and uterine Doppler. METHODS: prospective cohort study involving 244 pregnant women, 210 of them non-smokers and 34 smokers. Participants were submitted to four serial sonograms. The first was performed up to the 16th week of pregnancy to determine gestational age, and the other three at 28, 32 and 36 weeks for fetal biometry, evaluation of placental texture and Doppler studies of the uterine and umbilical arteries. Premature placental calcification was defined as grade III before 36 weeks. The chi2 and Fisher exact tests were used to compare placental grading, and the Mann-Whitney test to evaluate the resistance index of uterine and umbilical arteries. RESULTS: the frequency of grade III placenta and the resistance of the uterine arteries did not differ significantly between smokers and non-smokers, at all gestational ages. Umbilical artery Doppler was significantly higher in smokers than in non-smokers at 32 weeks. CONCLUSIONS: no association was found between cigarette smoking and premature placental calcification. Smoking was associated with increased umbilical artery resistance at 32 weeks.
Tobacco; Pregnancy complications; Placenta; Placental circulation; Laser-doppler flowmetry; Smoking
