Influence of Smoking during Pregnancy Specified as Cigarettes Per Day on Neonatal Anthropometric Measurements – an Analysis of the German Perinatal Survey

Abstract

Background and Aim: Smoking during pregnancy has a negative influence on prenatal growth. We investigated the relationship between the number of cigarettes smoked per day and anthropometric measurements of the neonate. Material and Methods: Datasets of 508 926 singleton pregnancies were available (441 409 of which included information on maternal smoking) from the German Perinatal Survey of 1998–2000. We analysed the birth weight, length, and head circumference as well as the neonatal growth indices weight/length, weight/head circumference, body mass index, and length/head circumference. Comparisons were made between the children of non-smoking women and those of women smoking 1–5, 6–10, 11–15, 16–20, 21–25, 26–30, or > 30 cigarettes per day (ANOVA, post-hoc tests according to Bonferroni). Analyses were performed for the total study population and for a restricted sample (deliveries after 37–41 completed weeks of gestation by women with a height ≥ 157 cm and a weight ≥ 54 kg) to limit confounding variables. Results: Analyses of birth weight, length, head circumference, weight/length, weight/head circumference, and body mass index revealed highly significant decreases (p < 0.001) in all smoking groups compared with non-smokers. There were monotonic decreases in these neonatal growth parameters with increasing smoking over the range 0–20 cigarettes per day. For more than 20 cigarettes per day “dose dependence” was less convincing but group sizes were relatively small. The growth index length/head circumference was not suitable to demonstrate a “dose-dependent” effect of smoking. Conclusions: Because smoking has a “dose-dependent” effect on a number of parameters of foetal growth, any reduction in cigarette consumption during pregnancy should be encouraged.