Open AccessSmoking during pregnancy increases the risk of preterm births among parous women
Author(s) -
KOLÅS TORIL,
NAKLING JAKOB,
SALVESEN KJELL Å.
Publication year - 2000
Publication title -
acta obstetricia et gynecologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.401
H-Index - 102
eISSN - 1600-0412
pISSN - 0001-6349
DOI - 10.1034/j.1600-0412.2000.079008644.x
Subject(s) - medicine , obstetrics , odds ratio , placenta previa , pregnancy , confidence interval , placental abruption , preeclampsia , premature birth , population , gestational age , confounding , relative risk , prospective cohort study , gynecology , gestation , placenta , fetus , environmental health , biology , genetics
Background. We wanted to study a possible association between smoking during pregnancy and preterm birth. Methods. A population based prospective study was performed among 7,236 consecutive pregnancies over seven years delivered at one birth clinic. Smoking habits were obtained at a routine ultrasound examination around 18 gestational weeks, and preterm birth was defined as delivery of a child between 24 and 37 gestational weeks. We estimated relative risk (odds ratio) between smoking, possible confounding variables and preterm birth using multiple logistic regression analysis. Results. Overall, 1,769 (25%) women said that they smoked every day during their pregnancy. The smoking women had an increased risk of preterm delivery compared with non‐smokers (odds ratio 1.53, 95% confidence interval 1.24, 1.89). However, this association was only demonstrated among the multiparous women (odds ratio 1.88, 95% confidence interval 1.39, 2.54). The association was statistically significant after adjusting for maternal age, diabetes, cervical conization, preeclampsia, placental abruption and placenta previa in a multivariate analysis, and we observed a dose‐response effect of maternal smoking on preterm birth among multiparous women. Conclusion. For multiparous women smoking during pregnancy increases the risk of preterm delivery, and there seems to be a dose‐response effect of smoking.