title: Body Mass Index, Smoking and Hypertensive Disorders during Pregnancy: A Population Based Case-Control Study.
abstract: While obesity is an indicated risk factor for hypertensive disorders of pregnancy, smoking during pregnancy has been shown to be inversely associated with the development of preeclampsia and gestational hypertension. The purpose of this study was to investigate the combined effects of high body mass index and smoking on hypertensive disorders during pregnancy. This was a case-control study based on national registers, nested within all pregnancies in Iceland 1989-2004, resulting in birth at the Landspitali University Hospital. Cases (n = 500) were matched 1:2 with women without a hypertensive diagnosis who gave birth in the same year. Body mass index (kg/m2) was based on height and weight at 10-15 weeks of pregnancy. We used logistic regression models to calculate odds ratios and corresponding 95% confidence intervals as measures of association, adjusting for potential confounders and tested for additive and multiplicative interactions of body mass index and smoking. Women's body mass index during early pregnancy was positively associated with each hypertensive outcome. Compared with normal weight women, the multivariable adjusted odds ratio for any hypertensive disorder was 1.8 (95% confidence interval, 1.3-2.3) for overweight women and 3.1 (95% confidence interval, 2.2-4.3) for obese women. The odds ratio for any hypertensive disorder with obesity was 3.9 (95% confidence interval 1.8-8.6) among smokers and 3.0 (95% confidence interval 2.1-4.3) among non-smokers. The effect estimates for hypertensive disorders with high body mass index appeared more pronounced among smokers than non-smokers, although the observed difference was not statistically significant. Our findings may help elucidate the complicated interplay of these lifestyle-related factors with the hypertensive disorders during pregnancy.
authors.affiliation: Faculty of Medicine, Centre of Public Health Sciences, University of Iceland, Reykjavík, Iceland.
authors.forename: Thuridur A
authors.initials: TA
authors.lastname: Gudnadóttir
authors.affiliation: Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America.|Department of Medicine, Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States of America.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Bateman
authors.affiliation: Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, United States of America.
authors.forename: Sonia
authors.initials: S
authors.lastname: Hernádez-Díaz
authors.affiliation: Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, United States of America.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Luque-Fernandez
authors.affiliation: Faculty of Medicine, Centre of Public Health Sciences, University of Iceland, Reykjavík, Iceland.|Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, United States of America.
authors.forename: Unnur
authors.initials: U
authors.lastname: Valdimarsdottir
authors.affiliation: Faculty of Medicine, Centre of Public Health Sciences, University of Iceland, Reykjavík, Iceland.
authors.forename: Helga
authors.initials: H
authors.lastname: Zoega
mesh_terms: D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications* / Q000453:epidemiology; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000453:epidemiology*; D012307:Risk Factors; D012907:Smoking; D055815:Young Adult