Impact of maternal cigarette smoking on fetal growth and body composition

Objective: The aim of this study was to determine the impact of maternal cigarette smoking on the fetal accretion of fat and lean body mass. We hypothesized that maternal smoking would result in a reduction in the deposition of lean body mass. Study Design: Longitudinal ultrasonographic examinations on 65 singleton fetuses without anomalies of smoking mothers were compared with 36 singleton fetuses without anomalies of nonsmoking mothers. A total of 214 ultrasonographic examinations were performed between 27 and 37 weeks’ gestation. All subjects underwent at least 2 ultrasonographic examinations separated by 4 weeks. We compared the slopes of the growth curves for individual morphometric parameters including head circumference, femur length, abdominal circumference, thigh muscle area, thigh fat area, estimated fetal weight and percentage of thigh fat between groups. Analysis was performed with a repeated measures analysis of covariance. Potential covariates included prepregnancy body mass index (in kilograms per square meter), weight gain during pregnancy, maternal age, parity, and fetal sex recorded at birth. Demographic variables are expressed as mean ± SD; fetal measurements are expressed as mean ± SE. Both t tests and χ 2 analyses were used to compare groups with respect to demographic variables. P < .05 was accepted for significance. Results: There were no significant differences between groups in maternal prepregnancy weight, maternal height, maternal prepregnancy body mass index, weight gain in pregnancy, parity, or fetal sex. Smokers were younger than nonsmokers (smokers, 23.7 ± 6.0 years; nonsmokers, 31.8 ± 6.0 years; P < .0001), and neonatal weight was reduced among smokers (smokers, 3269 ± 507 g; nonsmokers, 3519 ± 411 g; P < .01). There were no differences in the growth rates of head circumference ( P = .79) and femur length ( P = .67). Growth rates of abdominal circumference (smokers, 9.0 ± 0.3 mm/wk; nonsmokers, 10.3 ± 0.5 mm/wk; P = .01), estimated fetal weight (smokers, 171 ± 5.4 g/wk; nonsmokers, 193 ± 8.0 g/wk; P = .008), and muscle area (smokers, 64.1 ± 3.8 mm 2/wk; nonsmokers, 76.4 ± 5.6 mm 2/wk; P = .03) were significantly reduced among smokers. There was a reduction in the rate of fat deposition in the thighs of fetuses of smoking mothers (smokers, 38.7 ± 3.7 mm 2/wk; nonsmokers, 54.6 ± 5.4 mm 2/wk; P = .004); however there was no absolute difference in the amount of fat measured in the thigh between 33 and 37 weeks’ gestation. Conclu