Maternal Smoking During Pregnancy and the Risk of Psychiatric Morbidity in Singleton Sibling Pairs
: Mikael Ekblad, Liisa Lehtonen, Jyrki Korkeila, Mika Gissler
Publisher: OXFORD UNIV PRESS
: 2017
: Nicotine and Tobacco Research
: NICOTINE & TOBACCO RESEARCH
: NICOTINE TOB RES
: 19
: 5
: 597
: 604
: 8
: 1462-2203
: 1469-994X
DOI: https://doi.org/10.1093/ntr/ntx001
: https://research.utu.fi/converis/portal/detail/Publication/26505548
Introduction: Maternal smoking during pregnancy has been associated with an increased risk for psychiatric morbidity. We further studied this with Finnish siblings to control for genetic/familial factors.Methods: From the Finnish Medical Birth Register, sibling pairs were selected as the first two children born 1987-1995 to the same mother (n = 150 168 pairs), along with information on maternal smoking (no smoking/smoking). Information on the children's psychiatric diagnoses related to outpatient care visits (1998-2013) and inpatient care (1987-2013), and the mothers' psychiatric morbidity (1969-2013) was derived from the Finnish Hospital Discharge Register. The first pair analysis compared siblings of mothers who only smoked in the first pregnancy (Quitters, 4.7%) and mothers who smoked in both pregnancies (Smokers, 9.6%); the second analysis included mothers who smoked only in the second pregnancy (Starters, 3.3%) and mothers who did not smoke in either pregnancy (Nonsmokers, 77.5%). Smoking information was missing for 5.0% of pairs. Psychiatric morbidity of the siblings and mother was included in the statistical analyses.Results: The risk of psychiatric diagnoses was significantly lower for the second child of quitters (adjusted OR 0.77, 95% CI 0.72-0.83) compared to the risk among smokers. A higher risk for psychiatric diagnoses was found for the second child of starters (1.39, 1.30-1.49) compared to the risk among nonsmokers. The effect of smoking was more robust for externalizing diagnoses.Conclusions: Maternal smoking was independently associated with a higher risk for psychiatric morbidity in children, even when controlling thoroughly for genetic and familial factors.Implications: Maternal smoking during pregnancy has an independent effect on the risk of psychiatric morbidity in children, even after controlling for non-measurable genetic/familial factors by using a sibling pair design. The effect of maternal smoking was robust for externalizing diagnoses. Maternal smoking during pregnancy had an effect on diagnoses both in outpatient and inpatient care.