title: Smoking cessation in the first trimester reduces most obstetric risks, but not the risks of major congenital anomalies and admission to neonatal care: a population-based cohort study of 1,164,953 singleton pregnancies in Finland.
abstract: BACKGROUND
  In industrialised countries, approximately 5-20% of women smoke during pregnancy. We aim to study the association between smoking during pregnancy and adverse perinatal outcomes.
  
  
  METHODS
  A retrospective population-based cohort study using data on all singleton births between 1991 and 2010 (n=1,164,953) derived from the Finnish Medical Birth Register.
  
  
  RESULTS
  Of all the mothers included, 82.3% were non-smokers, 2.6% quit smoking during the first trimester of pregnancy, 12.5% smoked throughout pregnancy and 2.7% had no information on smoking. Continuing smoking after the first trimester of the pregnancy was associated with an increased prevalence of admission to a neonatal intensive care unit, stillbirth, preterm birth (<37 gestational weeks), low birth weight (LBW, <2500 g), small for gestational age (SGA, < -2 SDs) and major congenital anomaly compared with non-smokers. Smoking cessation reduced the risk of prematurity, stillbirth, LBW and SGA close to or at similar levels as those of non-smokers. Tobacco exposure in early pregnancy resulted in a 19% increased prevalence of admission to neonatal intensive care unit and a 22% increased prevalence of major congenital anomaly compared with non-smokers.
  
  
  CONCLUSIONS
  Smoking cessation appeared to reduce pregnancy risks close to those of non-smoking peers. Exposure to early pregnancy smoking was, however, associated with an increased admission to neonatal intensive care and an increased prevalence of major congenital anomalies.
authors.affiliation: Department of Obstetrics and Gynaecology, Kuopio University Hospital, , Kuopio, Finland.
authors.forename: Sari
authors.initials: S
authors.lastname: Räisänen
authors.forename: Ulla
authors.initials: U
authors.lastname: Sankilampi
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.forename: Michael R
authors.initials: MR
authors.lastname: Kramer
authors.forename: Tuovi
authors.initials: T
authors.lastname: Hakulinen-Viitanen
authors.forename: Juho
authors.initials: J
authors.lastname: Saari
authors.forename: Seppo
authors.initials: S
authors.lastname: Heinonen
mesh_terms: D000328:Adult; D015331:Cohort Studies; D000013:Congenital Abnormalities / Q000453:epidemiology*; D005260:Female; D005387:Finland; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D007363:Intensive Care Units, Neonatal / Q000706:statistics & numerical data; D008425:Maternal Behavior; D015999:Multivariate Analysis; D007744:Obstetric Labor Complications / Q000453:epidemiology / Q000517:prevention & control*; D018743:Perinatal Care / Q000706:statistics & numerical data; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D018566:Pregnancy, High-Risk; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D016540:Smoking Cessation; D012923:Social Class
keywords: Biostatistics; Obstetrics; Registers; Smoking; Socio-Economic