title: Active and passive maternal smoking during pregnancy and the risks of low birthweight and preterm birth: the Generation R Study.
abstract: The objective of this study was to examine the associations between active and passive smoking in different periods of pregnancy and changing smoking habits during pregnancy, with low birthweight and preterm birth. The study was embedded in the Generation R Study, a population-based prospective cohort study from early fetal life onwards in Rotterdam, The Netherlands. Active and passive smoking were assessed by questionnaires in early, mid- and late pregnancy. Analyses were based on 7098 pregnant women and their children. Active smoking until pregnancy was ascertained and was not associated with low birthweight and preterm birth. Continued active smoking after pregnancy was also recorded and was associated with low birthweight (adjusted odds ratio 1.75 [95% CI 1.20, 2.56]) and preterm birth (adjusted odds ratio 1.36 [95% CI 1.04, 1.78]). The strongest associations were found for active maternal smoking in late pregnancy. Passive maternal smoking in late pregnancy was associated with continuously measured birthweight (P for trend <0.001). For all active smoking categories in early pregnancy, quitting smoking was associated with a higher birthweight than continuing to smoke. Tendencies towards smaller non-significant beneficial effects on mean birthweight were found for reducing the number of cigarettes without quitting completely. This study shows that active and passive smoking in late pregnancy are associated with adverse effects on weight and gestational age at birth. Smoking in early pregnancy only, seems not to affect fetal growth adversely. Health care strategies for pregnant women should be aimed at quitting smoking completely rather than reducing the number of cigarettes.
authors.affiliation: The Generation R Study Group, and Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands. v.jaddoe@erasmusmc.nl
authors.forename: Vincent W V
authors.initials: VW
authors.lastname: Jaddoe
authors.forename: Ernst-Jan W M
authors.initials: EJ
authors.lastname: Troe
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.forename: Johan P
authors.initials: JP
authors.lastname: Mackenbach
authors.forename: Henriette A
authors.initials: HA
authors.lastname: Moll
authors.forename: Eric A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: Jacqueline C M
authors.initials: JC
authors.lastname: Witteman
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D009035:Mothers; D009426:Netherlands / Q000453:epidemiology; D011247:Pregnancy; D047928:Premature Birth / Q000209:etiology*; D011446:Prospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D016540:Smoking Cessation; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution