title: Timing of prenatal smoking cessation or reduction and infant birth weight: evidence from the United Kingdom Millennium Cohort Study.
abstract: Smoking during pregnancy is a key contributor to poor infant health. Our study presents a dynamic relationship between the timing of prenatal smoking cessation or reduction and infant birth weight. Using a large representative dataset of a birth cohort in the United Kingdom, we apply regression analysis to examine the influences of cessation in smoking or reduction in smoking intensity at different months or trimesters on infant birth weight. For robustness checks, we use a rich set of additional covariates, a series of variable selection procedures, alternative birth outcome measures, and stratified samples. We find robust evidence that mothers who quit smoking by the third month of pregnancy or the end of the first trimester have infants of the same weight as those infants of nonsmokers. However, we find smoking cessation in the fourth month or any time beyond is associated with substantially lower infant birth weights. Two-thirds of the total adverse smoking impact on infant birth weight occurs in the second trimester. Our study also shows mothers who smoke throughout pregnancy but cut smoking intensity by the third month in pregnancy deliver infants of the same weight as those infants born to persistent light smokers. Our research suggests the efficacy of prenatal smoking cessation services can be significantly improved, if health professionals can encourage more pregnant women to quit smoking or reduce smoking intensity timely by the end of the first trimester.
authors.affiliation: Department of Economics, Appalachian State University, ASU Box 32051, Boone, NC, 28608, USA, yanj@appstate.edu.
authors.forename: Ji
authors.initials: J
authors.lastname: Yan
authors.forename: Peter A
authors.initials: PA
authors.lastname: Groothuis
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D005317:Fetal Growth Retardation / Q000209:etiology; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007236:Infant, Small for Gestational Age; D018811:Maternal Exposure / Q000009:adverse effects*; D009035:Mothers / Q000523:psychology* / Q000706:statistics & numerical data; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011264:Pregnancy Trimesters; D012907:Smoking / Q000009:adverse effects*; D016540:Smoking Cessation; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult