Fetal growth and development disorders in smoking pregnant women

BACKGROUND: Due to the increased frequency of smoking in pregnant women, an interest in the study of the mechanisms of the fetoplacental unit in women with tobacco addiction has also been increased all over the world. The effect of low degrees of tobacco addiction of a pregnant woman on the fetus has not been studied in the available literature.

AIM: The aim of this study was to identify the growth and developmental abnormalities of the fetus at 30-34 weeks of gestation in smoking pregnant women at the third-trimester ultrasound screening.

MATERIALS AND METHODS: Pregnant women, who were observed in the Northern Medical Clinical Center named after N.A. Semashko, Arkhangelsk, Russia were examined during the ultrasound screening. A continuous examination of pregnant women with three ultrasound screenings was carried out, with the third screening performed in 1048 individuals.

RESULTS: The survey cohort included 120 pregnant women using the inclusion criteria. Two groups were formed depending on the presence or absence of smoking during pregnancy. The first group contained non-smoking pregnant women (n = 40); the second group comprised smokers during pregnancy (n = 80). Comparison of fetal development parameters in the group of pregnant smokers was carried out in two subgroups: the second “a” subgroup only consisted of smokers in the first trimester (embryonic period) and the second “b” subgroup contained smokers throughout pregnancy. All pregnant women who took part in the study signed a Patient Informed Consent form. The study design was observational, cross-sectional (one-step). The main manifestations of fetal growth and development disorders at 30-34 weeks of gestation in pregnant smokers were low estimated fetal weight, low tubular bone length and low head circumference by the gestational age. Low (below the 10th percentile) estimated fetal weight by the gestational age was recorded only in the group of pregnant women who smoke (p = 0.001) and in 90.0% of cases even with a weak degree of tobacco addiction. It was accompanied by low bone sizes and was detected in 10.0% of cases among women who stopped smoking in the first trimester and in 15.0% of cases among those who continued to smoke throughout pregnancy. This result confirmed early symmetrical intrauterine growth restriction of the fetus. Pregnant smokers at 30-34 weeks of gestation had significantly more often low (below the 5^th percentile) fetometric parameters characterizing bone growth: femur length (p = 0.01), shinbone length (p = 0.035), shoulder bone length (p = 0.004), biparietal head size (p = 0.006), and head circumference (p = 0.002). Low values of the fetal head circumference were found in 50.0% of cases among pregnant smokers. In the absence of signs of fetal bone growth restriction and the estimated fetal weight in P10-95 values in the group of smoking pregnant women, significantly more often (p = 0.027) than in non-smokers, low (below the 5^th percentile) head circumference for gestational age was recorded in 29.8% of cases. In addition, in this group of fetuses of pregnant smokers, elevated ratios of abdominal circumference to head circumference were found, which indicated fetal head growth restriction. The fetometry data obtained were confirmed by anthropometric measurements in the newborns during term delivery, the length of full-term newborns in pregnant smokers being significantly lower (p = 0.040).

CONCLUSIONS: Fetuses of pregnant smokers were more likely to have low fetometric parameters by gestational age. Low estimated weights of the fetuses were found in 90.0% of cases with a weak degree of tobacco addiction.