@article{3104017,
    title = "Changes in parental smoking during pregnancy and risks of adverse birth outcomes and childhood overweight in Europe and North America: An individual participant data meta-analysis of 229,000 singleton births",
    author = "Philips, E.M. and Santos, S. and Trasande, L. and Aurrekoetxea, J.J. and Barros, H. and von Berg, A. and Bergström, A. and Bird, P.K. and Brescianini, S. and Chaoimh, C.N. and Charles, M.-A. and Chatzi, L. and Chevrier, C. and Chrousos, G.P. and Costet, N. and Criswell, R. and Crozier, S. and Eggesbø, M. and Fantini, M.P. and Farchi, S. and Forastiere, F. and van Gelder, M.M.H.J. and Georgiu, V. and Godfrey, K.M. and Gori, D. and Hanke, W. and Heude, B. and Hryhorczuk, D. and Iñiguez, C. and Inskip, H. and Karvonen, A.M. and Kenny, L.C. and Kull, I. and Lawlor, D.A. and Lehmann, I. and Magnus, P. and Manios, Y. and Melén, E. and Mommers, M. and Morgen, C.S. and Moschonis, G. and Murray, D. and Nohr, E.A. and Nybo Andersen, A.-M. and Oken, E. and Oostvogels, A.J.J.M. and Papadopoulou, E. and Pekkanen, J. and Pizzi, C. and Polanska, K. and Porta, D. and Richiardi, L. and Rifas-Shiman, S.L. and Roeleveld, N. and Rusconi, F. and Santos, A.C. and Sørensen, T.I.A. and Standl, M. and Stoltenberg, C. and Sunyer, J. and Thiering, E. and Thijs, C. and Torrent, M. and Vrijkotte, T.G.M. and Wright, J. and Zvinchuk, O. and Gaillard, R. and Jaddoe, V.W.V.",
    journal = "PLoS Medicine",
    year = "2020",
    volume = "17",
    number = "8",
    publisher = "Public Library of Science",
    issn = "1549-1277, 1549-1676",
    doi = "10.1371/JOURNAL.PMED.1003182",
    keywords = "adult;  Article;  birth weight;  body mass;  childhood obesity;  cohort analysis;  controlled study;  Europe;  female;  gestational age;  meta analysis;  North America;  parental smoking;  pregnancy;  pregnancy outcome;  premature labor;  risk factor;  adverse event;  child parent relation;  childhood obesity;  human;  male;  newborn;  pregnancy;  prematurity;  prenatal exposure;  risk factor;  smoking, Cohort Studies;  Europe;  Female;  Gestational Age;  Humans;  Infant, Newborn;  Male;  North America;  Parents;  Pediatric Obesity;  Pregnancy;  Premature Birth;  Prenatal Exposure Delayed Effects;  Risk Factors;  Smoking",
    abstract = "Background Fetal smoke exposure is a common and key avoidable risk factor for birth complications and seems to influence later risk of overweight. It is unclear whether this increased risk is also present if mothers smoke during the first trimester only or reduce the number of cigarettes during pregnancy, or when only fathers smoke. We aimed to assess the associations of parental smoking during pregnancy, specifically of quitting or reducing smoking and maternal and paternal smoking combined, with preterm birth, small size for gestational age, and childhood overweight.
Methods and findings We performed an individual participant data meta-analysis among 229,158 families from 28 pregnancy/birth cohorts from Europe and North America. All 28 cohorts had information on maternal smoking, and 16 also had information on paternal smoking. In total, 22 cohorts were population-based, with birth years ranging from 1991 to 2015. The mothers’ median age was 30.0 years, and most mothers were medium or highly educated. We used multilevel binary logistic regression models adjusted for maternal and paternal sociodemographic and lifestyle-related characteristics. Compared with nonsmoking mothers, maternal first trimester smoking only was not associated with adverse birth outcomes but was associated with a higher risk of childhood overweight (odds ratio [OR] 1.17 [95% CI 1.02–1.35], P value = 0.030). Children from mothers who continued smoking during pregnancy had higher risks of preterm birth (OR 1.08 [95% CI 1.02–1.15], P value = 0.012), small size for gestational age (OR 2.15 [95% CI 2.07–2.23], P value < 0.001), and childhood overweight (OR 1.42 [95% CI 1.35–1.48], P value < 0.001). Mothers who reduced the number of cigarettes between the first and third trimester, without quitting, still had a higher risk of small size for gestational age. However, the corresponding risk estimates were smaller than for women who continued the same amount of cigarettes throughout pregnancy (OR 1.89 [95% CI 1.52–2.34] instead of OR 2.20 [95% CI 2.02–2.42] when reducing from 5–9 to ≤4 cigarettes/day; OR 2.79 [95% CI 2.39–3.25] and OR 1.93 [95% CI 1.46–2.57] instead of OR 2.95 [95% CI 2.75–3.15] when reducing from ≥10 to 5–9 and ≤4 cigarettes/day, respectively [P values < 0.001]). Reducing the number of cigarettes during pregnancy did not affect the risks of preterm birth and childhood overweight. Among nonsmoking mothers, paternal smoking was associated with childhood overweight (OR 1.21 [95% CI 1.16–1.27], P value < 0.001) but not with adverse birth outcomes. Limitations of this study include the self-report of parental smoking information and the possibility of residual confounding. As this study only included participants from Europe and North America, results need to be carefully interpreted regarding other populations. Conclusions We observed that as compared to nonsmoking during pregnancy, quitting smoking in the first trimester is associated with the same risk of preterm birth and small size for gestational age, but with a higher risk of childhood overweight. Reducing the number of cigarettes, without quitting, has limited beneficial effects. Paternal smoking seems to be associated, independently of maternal smoking, with the risk of childhood overweight. Population strategies should focus on parental smoking prevention before or at the start, rather than during, pregnancy. © 2020 Philips et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited."
}