Smoking habits, environmental tobacco smoke exposure, coffee intake and adverse pregnancy outcomes: a case-control study in Italy.

Introduction: It is well known that some life-style habits in pregnancy may influence fetal growth. Active maternal smoking is a well recognised risk of adverse pregnancy outcome, mainly low birth weight. Recent studies report that environmental tabacco smoke (ETS) exposure adversely affects fetal growth with an elevated risk of low birth weight. Also coffee or alcohol intake during pregnancy has been linked to adverse reproductive outcomes. The aim of this study was to investigate the effects of maternal smoking habits, ETS exposure and maternal coffee and alcohol intake throughout the last trimester of pregnancy on preterm delivery (PD) and on small for gestational age at term (term SGA). Methods: A case-control study was carried out between October 1999 and September 2000 in 9 italian cities (Genoa, Udine, Modena, Parma, Siena, Roma, L'Aquila, Naples and Catania). 525 preterm cases (children born between the 26th to the 38th week of pregnancy) and 317 term SGA (children born fron the 38th week and weighted under the 10th percentile of weight) were recruited. Controls (n. 871) were singleton birth matched to the cases by sex, center and calendar week of birth, whose gestational age was >=38 weeks and weight >=10th percentile. Data were collected by a validated, self-administered questionnaire; it referred the last trimester of pregnancy and included four parts. The first collected socio-demographic data, the second gathered information about nutritional habits and water consumption, the third assessed the woman's life stile during the last three months of pregnancy, the fourth gathered data on woman's health status. Univariate and multivariate logistic regression analyses were performed in order to estimate odds ratios. Results: According to univariate analyses, risk of term SGA increased with increasing cigarette smoking during pregnancy (OR: 2.09, 95%CI: 1.45-3.00 for 1-9 cigarettes/day, and OR = 2.76, 95%CI: 1.67-4.45 for 10 cigarettes and more/day). Regarding to PD, it was observed a OR: 1.47, 95%CI: 1.05-2.04 for 1-9 cigarettes/day and a OR: 1,30 95%CI: 0.78-4.81 for 10 cigarettes/day. Exposure to ETS appeared to be mainly related to term SGA, when there were more than two smokers at home (OR: 3.05, 95%CI: 1.19-7.79). Alcohol and coffee intake were not associated with term SGA (OR: 1.31, 95%CI: 0.89-1.93 and OR: 0.90, 95%CI: 0.42-1.93, respectively). According to multivariate logistic analyses, adjusting for socio-demografic variables and life-stile habits, only the influence of active smoking on term SGA was confirmed (Adjusted OR = 2.49, 95%CI: 1.74-3.56). Conclusions: This study provides clear evidence that maternal smoke in pregnancy influence term SGA. No adverse effect on fetal growth was observed in ralation to coffee and alcohol intake, while maternal EST exposure didn't reach the statistical significance due to the small number of women heavily exposed.