Smoking during pregnancy according to obstetric complications and parity: results of the EUROPOP study

Abstract

This study aimed to analyse the relationship between smoking and preterm birth (22-36 weeks) according to the main obstetric complications leading to the preterm birth, both overall and by parity. The EUROPOP study is a case-control study carried out between 1994 and 1997; 3,787 preterm and 5,602 full-term births were included, from maternity units in 10 countries, using the same protocol. Social, demographic and medical information was collected after delivery, from obstetric records and interviews with the mothers. Cases were classified according to the main obstetric complication (hypertension, haemorrhage, preterm premature rupture of membranes (PPROM), idiopathic spontaneous preterm labour, intrauterine growth retardation, all other causes). Multiple logistic regression analysis was used to control for confounders. Twenty four percent of cases and 20% of controls were smokers. Smoking during pregnancy, heavy smoking (>or=10 cigarettes per day) in particular, was a risk factor for preterm birth (aOR = 1.39, 95% CI:1.20-1.60). Smoking increased the risk of preterm delivery due to all obstetric complications other than hypertension. For these complications, the risk of preterm delivery associated with smoking was higher for multiparae (aOR = 1.46, 95% CI:1.24-1.71) than for primiparae (aOR = 1.18, 95% CI:1.00-1.38). In conclusion, smoking during pregnancy increases the risk of preterm birth among women with all obstetric complications except hypertension. This association is stronger in multiparae than in primiparae and the risk is higher for heavy smokers.

Tobacco and pregnancy: Overview of exposures and effects

“…A dose response relationship between maternal smoking and the incidence of preterm birth has been repeatedly observed (Kyrklund-Blomberg and Cnattingius, 1998;Fantuzzi et al, 2007;Nabet et al, 2007). Maternal smoking has also been associated with increased risk of very preterm birth, particularly in multiparous women (Cnattingius et al, 1999;Burguet et al, 2004;Fantuzzi et al, 2007).…”

The Generation R Study: design and cohort update 2012

“…The major pregnancy outcomes, including live births, induced abortion fetal or perinatal loss, pregnancy induced hypertension, preeclampsia, and gestational diabetes are known in 99% of all enrolled mothers. These outcomes are related to various exposures of interest [132][133][134][135][136][137][138][139][140][141][142][143][144][145][146][147][148]. In all children known to be born alive, information about sex, birth weight and gestational age is available.…”

Smoking and Reproduction

“…There is much evidence that smoking in pregnancy is a risk factor for preterm as well as very preterm births [102,103] . Active [100,104,105] and passive smoking [106 -110] of pregnant women is well known to result in lower birth weights of their infants.…”