title: Prepregnancy Obesity and Risks of Stillbirth.
abstract: 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.
  
  
  CONCLUSIONS
  Increased risks were observed across all gestational ages, and some evidence of heterogeneity of the associations was observed by race-ethnicity and parity.
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Suzan L
authors.initials: SL
authors.lastname: Carmichael
authors.affiliation: Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Yair J
authors.initials: YJ
authors.lastname: Blumenfeld
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Mayo
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Emily
authors.initials: E
authors.lastname: Wei
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Gould
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: David K
authors.initials: DK
authors.lastname: Stevenson
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Gary M
authors.initials: GM
authors.lastname: Shaw
mesh_terms: D000328:Adult; D044383:Black People; D001835:Body Weight; D002140:California; D005006:Ethnicity; D005260:Female; D005865:Gestational Age; D006801:Humans; D008875:Middle Aged; D009035:Mothers; D009765:Obesity / Q000150:complications*; D010298:Parity; D016012:Poisson Distribution; D011247:Pregnancy; D011248:Pregnancy Complications; D012307:Risk Factors; D050497:Stillbirth; D013997:Time Factors; D044465:White People; D055815:Young Adult; D001741:Black or African American