Smoking during pregnancy and its effect on placental weight: A Mendelian randomization study.

Autor:	Jaitner A; Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK., Vaudel M; Mohn Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway.; Department of Genetics and Bioinformatics, Division of Health Data and Digitalization, Norwegian Institute of Public Health, Oslo, Norway.; Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway., Tsaneva-Atanasova K; Department of Mathematics and Statistics, Faculty of Environment, Science and Economy, University of Exeter, Exeter, UK.; EPSRC Hub for Quantitative Modelling in Healthcare University of Exeter, Exeter, UK., Njølstad PR; Mohn Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway.; Children and Youth Clinic, Haukeland University Hospital, Bergen, Norway., Jacobsson B; Department of Genetics and Bioinformatics, Division of Health Data and Digitalization, Norwegian Institute of Public Health, Oslo, Norway.; Department of Obstetrics and Gynecology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.; Department of Obstetrics and Gynecology, Sahlgrenska University Hospital, Gothenburg, Gothenburg, Sweden., Bowden J; Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK.; Novo Nordisk Genetics Centre of Excellence, Oxford, UK., Johansson S; Mohn Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway.; Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway., Freathy RM; Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK.
Jazyk:	angličtina
Zdroj:	MedRxiv : the preprint server for health sciences [medRxiv] 2023 Aug 25. Date of Electronic Publication: 2023 Aug 25.
DOI:	10.1101/2023.08.24.23294537
Abstrakt:	Background: The causal relationship between maternal smoking in pregnancy and reduced offspring birth weight is well established and is likely due to impaired placental function. However, observational studies have given conflicting results on the association between smoking and placental weight. We aimed to estimate the causal effect of newly pregnant mothers quitting smoking on their placental weight at the time of delivery. Methods: We used one-sample Mendelian randomization, drawing data from the Avon Longitudinal Study of Parents and Children (ALSPAC) (up to N = 805) and the Norwegian Mother, Father and Child Cohort Study (MoBa) (up to N = 4475). The analysis was performed in pre-pregnancy smokers only, due to the specific role of the genetic instrument SNP rs1051730 ( CHRNA5 - CHRNA3 - CHRNB4 ) in affecting smoking cessation but not initiation. Results: Fixed effect meta-analysis showed a 175 g [95%CI: 16, 334] higher placental weight for pre-pregnancy smoking mothers who continued smoking at the beginning of pregnancy, compared with those who stopped smoking. Using the number of cigarettes smoked per day in the first trimester as the exposure, the causal estimate was a 12 g [95%CI: 2,22] higher placental weight per cigarette per day. Results were similar when the smoking exposures were measured at the end of pregnancy. Using the residuals of birth weight regressed on placental weight as the outcome, we showed weak evidence of lower offspring birth weight relative to the placental weight for continuing smoking. Conclusion: Our results suggest that continued smoking during pregnancy causes higher placental weights. Competing Interests: Conflict of interest The authors report no conflict of interest.
Databáze:	MEDLINE
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