title: Association Between Maternal Smoking During Pregnancy and Birth Weight: An Appropriately Adjusted Model From the Japan Environment and Children's Study.
abstract: BACKGROUND
  There has been no large nationwide population-based study to examine the effects of maternal smoking status during pregnancy on birth weight that simultaneously controlled for clinical information, socioeconomic status, and maternal weight. Thus, this study aimed to determine the association between maternal smoking status during pregnancy and birth weight, while taking these confounding factors into consideration.
  
  
  METHODS
  This study examined the first-year fixed dataset from a large nationwide birth cohort study that commenced in 2011. The dataset consisted of information on 9369 singleton infants born before December 31, 2011. Children were divided into 4 groups for statistical analysis: those born to mothers who did not smoke (NS), who quit smoking before pregnancy, who quit smoking during early pregnancy, and who smoked (SM). Multiple linear regression models were conducted for each sex to examine the association between maternal smoking status during early pregnancy and fetal growth. Birth weight was estimated using the least-squares method after controlling for covariates.
  
  
  RESULTS
  After controlling for potential confounding factors, maternal smoking status during pregnancy was significantly associated with birth weight. There was a significant difference in birth weight between NS and SM for both male and female infants (male infants, 3096.2 g [NS] vs 2959.8 g [SM], P < 0.001; female infants, 3018.2 g [NS] vs 2893.7 g [SM], P < 0.001).
  
  
  CONCLUSIONS
  Using data from a large nationwide birth cohort study in Japan, we have shown that maternal smoking during pregnancy may reduce birth weight by 125-136 g.
authors.affiliation: Department of Health Sciences, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi.
authors.forename: Kohta
authors.initials: K
authors.lastname: Suzuki
authors.forename: Ryoji
authors.initials: R
authors.lastname: Shinohara
authors.forename: Miri
authors.initials: M
authors.lastname: Sato
authors.forename: Sanae
authors.initials: S
authors.lastname: Otawa
authors.forename: Zentaro
authors.initials: Z
authors.lastname: Yamagata
mesh_terms: D000328:Adult; D001724:Birth Weight; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007564:Japan / Q000453:epidemiology; D016014:Linear Models; D008297:Male; D011247:Pregnancy; D037841:Pregnant People / Q000523:psychology*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D055815:Young Adult