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Obes Rev. 2018 Sep;19(9):1248-1255. doi: 10.1111/obr.12698. Epub 2018 Jul 23.

Differences in maternal smoking across successive pregnancies - dose-dependent relation to BMI z-score in the offspring: an individual patient data (IPD) meta-analysis.

Author information

1
Institute of Social Paediatrics and Adolescents Medicine, Division of Epidemiology, Ludwig-Maximilians-University Munich, Munich, Germany.
2
Department of Epidemiology, Brown University School of Public Health, Providence, RI, USA.
3
Adelaide Medical School, The Robinson Research Institute, The University of Adelaide, Adelaide, SA, Australia.
4
Obesity Prevention Program, Department of Population Medicine, Harvard Medical School, Harvard Pilgrim Health Care Institute, Boston, MA, USA.
5
Rotman Research Institute and Departments of Psychology and Psychiatry, University of Toronto, Toronto, ON, Canada.
6
Hospital for Sick Children and Departments of Physiology and Nutritional Sciences, University of Toronto, Toronto, ON, Canada.
7
Centers for Disease Control and Prevention, Atlanta, GA, USA.
8
Health Behavior Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA.
9
Department of Social and Behavioral Sciences, Harvard TH Chan School of Public Health, Boston, MA, USA.
10
Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, USA.
11
Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.

Abstract

INTRODUCTION:

Uncontrolled family factors may bias the estimation of the association between maternal smoking during pregnancy and offspring body mass index (BMI). The objective was to assess if there is an association between maternal smoking during pregnancy and offspring BMI z-score independent of factors in the siblings' shared environment and if such association is linear.

METHODS:

We performed an individual patient data meta-analysis using five studies providing sibling data (45,299 children from 14,231 families). In a multi-level model, separating within-family and between-family effects and with random intercept for families, we analysed the dose-response association between maternal number of cigarettes per day during pregnancy and offspring's BMI z-score using B-splines to allow for non-linear associations.

RESULTS:

A linear within-family effect for number of cigarettes smoked in the range from 1 to 30 cigarettes per day on the offspring's BMI z-score was observed. Each additional cigarette per day between sibling pregnancies resulted in an increase in BMI z-score of 0.007 (95% CI [0.006, 0.009]). A between family-effect emerged only with doses ≥25 cigarettes per day.

CONCLUSIONS:

The number of cigarettes mothers smoke per day during pregnancy is positively associated with offspring BMI z-score even among siblings, suggesting that the association is not entirely explained by confounding by family factors.

KEYWORDS:

Family factors; offspring; siblings; smoking

PMID:
30035359
PMCID:
PMC6107372
DOI:
10.1111/obr.12698
[Indexed for MEDLINE]
Free PMC Article

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