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Prepregnancy Obesity and Risks of Stillbirth.

CPQCC Publication
TitlePrepregnancy Obesity and Risks of Stillbirth.
Publication TypeJournal Article
Year of Publication2015
AuthorsCarmichael SL, Blumenfeld YJ, Mayo J, Wei E, Gould JB, Stevenson DK, Shaw GM
Corporate AuthorsMarch of Dimes Prematurity Research Center at Stanford University School of Medicine
JournalPLoS One
Date Published2015
KeywordsAdult, African Continental Ancestry Group, Body Weight, California, Ethnic Groups, European Continental Ancestry Group, Female, Gestational Age, Humans, Middle Aged, Mothers, Obesity, Parity, Poisson Distribution, Pregnancy, Pregnancy Complications, Risk Factors, Stillbirth, Time Factors, Young Adult

BACKGROUND: We examined the association of maternal obesity with risk of stillbirth, focusing on whether the pattern of results varied by gestational age or maternal race-ethnicity or parity.

METHODS: Analyses included 4,012 stillbirths and 1,121,234 liveborn infants delivered in California from 2007-2010. We excluded stillbirths due to congenital anomalies, women with hypertensive disorders or diabetes, and plural births, to focus on fetuses and women without these known contributing conditions. We used Poisson regression to estimate relative risks (RR) and 95% confidence intervals (CI). Separate models were run for stillbirths delivered at 20-23, 24-27, 28-31, 32-36, 37-41 weeks, relative to liveborn deliveries at 37-41 weeks.

RESULTS: For stillbirth at 20-23 weeks, RRs were elevated for all race-ethnicity and parity groups. The RR for a 20-unit change in BMI (which reflects the approximate BMI difference between a normal weight and an Obese III woman) was 3.5 (95% CI 2.2, 5.6) for nulliparous white women and ranged from 1.8 to 5.0 for other sub-groups. At 24-27 weeks, the association was significant (p<0.05) only for multiparous non-Hispanic whites; at 28-31 weeks, for multiparous whites and nulliparous whites and blacks; at 32-36 weeks, for multiparous whites and nulliparous blacks; and at 37-41 weeks, for all groups except nulliparous blacks. The pattern of results was similar when restricted to stillbirths due to unknown causes and somewhat stronger when restricted to stillbirths attributable to obstetric causes.

CONCLUSION: Increased risks were observed across all gestational ages, and some evidence of heterogeneity of the associations was observed by race-ethnicity and parity.

Alternate JournalPLoS One
PubMed ID26466315
PubMed Central IDPMC4605840