title: Maternal prepregnancy obesity and cause-specific stillbirth.
abstract: BACKGROUND
  In high-income countries, maternal obesity is one of the most important modifiable causes of stillbirth, yet the pathways underpinning this association remain unclear.
  
  
  OBJECTIVE
  We estimated the association between maternal prepregnancy body mass index (BMI) and the risk of stillbirth defined by pathophysiologic contributors or causes.
  
  
  METHODS
  Using a case-cohort design, we randomly sampled 1829 singleton deliveries from a cohort of 68,437 eligible deliveries at Magee-Womens Hospital in Pittsburgh, Pennsylvania (2003-2010), and augmented it with all remaining cases of stillbirth for a total of 658 cases. Stillbirths were classified based on probable cause(s) of death (maternal medical conditions, obstetric complications, fetal abnormalities, placental diseases, and infection). A panel of clinical experts reviewed medical records, placental tissue slides and pathology reports, and fetal postmortem reports of all stillbirths. Causes of fetal death were assigned by using the Stillbirth Collaborative Research Network Initial Causes of Fetal Death protocol from the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Proportional hazards models were used to estimate the BMI-stillbirth association after adjustment for confounders.
  
  
  RESULTS
  The rate of stillbirth among lean, overweight, obese, and severely obese women was 7.7, 10.6, 13.9, and 17.3 per 1000 live-born and stillborn infants, respectively. Adjusted stillbirth HRs (95% CIs) were 1.4 (1.1, 1.8) for overweight, 1.8 (1.3, 2.4) for obese, and 2.0 (1.5, 2.8) for severely obese women, respectively, compared with lean women; associations strengthened when limited to antepartum stillbirths. Obesity and severe obesity were associated with stillbirth resulting from placental diseases, hypertension, fetal anomalies, and umbilical cord abnormalities. BMI was not related to stillbirth caused by placental abruption, obstetric conditions, or infection.
  
  
  CONCLUSIONS
  Multiple mechanisms appear to link obesity to stillbirth. Interventions to reduce stillbirth among obese mothers should consider targeting stillbirth due to hypertension and placental diseases-the most common causes of fetal death in this at-risk group.
authors: Department of Epidemiology, Graduate School of Public Health, Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, and Magee-Womens Research Institute, Pittsburgh, PA; and lbodnar@pitt.edu.
authors: Lisa M
authors: http://orcid.org/0000-0001-9427-5467
authors: LM
authors: Bodnar
authors: Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, and Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA; Magee-Womens Research Institute, Pittsburgh, PA; and.
authors: W Tony
authors: WT
authors: Parks
authors: Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, and.
authors: Kiran
authors: K
authors: Perkins
authors: Department of Epidemiology, Graduate School of Public Health.
authors: Sarah J
authors: SJ
authors: Pugh
authors: Departments of Pediatrics and of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Canada.
authors: Robert W
authors: RW
authors: Platt
authors: Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, and.
authors: Maisa
authors: M
authors: Feghali
authors: Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, and.
authors: Karen
authors: K
authors: Florio
authors: Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, and.
authors: Omar
authors: O
authors: Young
authors: Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, and.
authors: Sarah
authors: S
authors: Bernstein
authors: Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, and Magee-Womens Research Institute, Pittsburgh, PA; and.
authors: Hyagriv N
authors: HN
authors: Simhan
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000503:physiopathology; D009765:Obesity / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology; D010414:Pennsylvania; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D012189:Retrospective Studies; D050497:Stillbirth / Q000453:epidemiology*; D014470:Umbilical Cord / Q000002:abnormalities; D055815:Young Adult
keywords: body mass index; fetal death; obesity; pregnancy; stillbirth; weight; women