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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

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
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
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.
1549-1277
1-25
Philips, Elise M.
23ae9313-c49b-46bc-8e54-f9dff19ef275
Santos, Susana
89a091a6-0b13-4f1e-ab8f-eb58f21d8e71
Trasande, Leonardo
4e34b9d9-95b5-4450-ad7a-d3549cb62fa3
Aurrekoetxea, Juan J.
48cf083d-f364-4888-944c-210c7ce04b80
von Berg, Andrea
caef3359-e855-4a42-8029-875cb8661312
Crozier, Sarah
9c3595ce-45b0-44fa-8c4c-4c555e628a03
Godfrey, Keith
0931701e-fe2c-44b5-8f0d-ec5c7477a6fd
Inskip, Hazel
5fb4470a-9379-49b2-a533-9da8e61058b7
et al.
Philips, Elise M.
23ae9313-c49b-46bc-8e54-f9dff19ef275
Santos, Susana
89a091a6-0b13-4f1e-ab8f-eb58f21d8e71
Trasande, Leonardo
4e34b9d9-95b5-4450-ad7a-d3549cb62fa3
Aurrekoetxea, Juan J.
48cf083d-f364-4888-944c-210c7ce04b80
von Berg, Andrea
caef3359-e855-4a42-8029-875cb8661312
Crozier, Sarah
9c3595ce-45b0-44fa-8c4c-4c555e628a03
Godfrey, Keith
0931701e-fe2c-44b5-8f0d-ec5c7477a6fd
Inskip, Hazel
5fb4470a-9379-49b2-a533-9da8e61058b7

Philips, Elise M., Santos, Susana, Trasande, Leonardo, Aurrekoetxea, Juan J. and von Berg, Andrea , et al. (2020) 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. PLoS Medicine, 17 (18), 1-25, [e1003182]. (doi:10.1371/journal.pmed.1003182).

Record type: Article

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.

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Accepted/In Press date: 9 July 2020
Published date: 18 August 2020

Identifiers

Local EPrints ID: 443334
URI: http://eprints.soton.ac.uk/id/eprint/443334
ISSN: 1549-1277
PURE UUID: 09651828-0235-4dab-abc1-8ead92ad4fbc
ORCID for Sarah Crozier: ORCID iD orcid.org/0000-0002-9524-1127
ORCID for Keith Godfrey: ORCID iD orcid.org/0000-0002-4643-0618
ORCID for Hazel Inskip: ORCID iD orcid.org/0000-0001-8897-1749

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Date deposited: 20 Aug 2020 16:34
Last modified: 26 Nov 2021 02:44

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Contributors

Author: Elise M. Philips
Author: Susana Santos
Author: Leonardo Trasande
Author: Juan J. Aurrekoetxea
Author: Andrea von Berg
Author: Sarah Crozier ORCID iD
Author: Keith Godfrey ORCID iD
Author: Hazel Inskip ORCID iD
Corporate Author: et al.

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