title: Risk of adverse pregnancy outcomes stratified for pre-pregnancy body mass index.
abstract: OBJECTIVE
  To estimate the risk of adverse maternal and perinatal outcomes in women with different pre-pregnancy body mass index (BMI).
  
  
  METHODS
  We conducted a cohort study with 14 451 singleton pregnancies in 15 medical centers in Beijing between 20 June 2013 and 30 November 2013 using cluster random sampling. We divided participants into four groups based on pre-pregnancy BMI: Group A (underweight): BMI < 18.5 kg/m(2), Group B (normal): 18.5-23.9 kg/m(2), Group C (overweight): 24-27.9 kg/m(2), Group D (obesity): ≥28 kg/m(2). We used multivariate analysis to evaluate the association of the risk of adverse pregnancy outcomes and pre-pregnancy BMI.
  
  
  RESULTS
  The prevalence of maternal overweight and obesity was 14.82% (2142/14 451) and 4.71% (680/14 451) in the study population, respectively. Higher pre-pregnancy BMI is associated with higher prevalence of gestational diabetes (GDM), macrosomia, Cesarean section (C-section), preeclampsia and postpartum hemorrhage. Pre-pregnancy overweight or obesity increases the risk of adverse pregnancy outcomes, regardless of GDM status.
  
  
  CONCLUSIONS
  Pre-pregnancy overweight or obesity is associated with increased risk of adverse pregnancy outcomes. Nutrition counseling is recommended before pregnancy in women who have overweight or obesity.
authors.affiliation: a Peking University First Hospital , Beijing , China .
authors.forename: Yu-Mei
authors.initials: YM
authors.lastname: Wei
authors.affiliation: a Peking University First Hospital , Beijing , China .
authors.forename: Hui-Xia
authors.initials: HX
authors.lastname: Yang
authors.affiliation: a Peking University First Hospital , Beijing , China .
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Zhu
authors.affiliation: b Pharmaceutical Outcomes and Policy, College of Pharmacy, University of Florida , FL , USA .
authors.forename: Xin-Yue
authors.initials: XY
authors.lastname: Liu
authors.affiliation: c Tongzhou Maternal and Child Health Hospital of Beijing , Beijing , China .
authors.forename: Wen-Ying
authors.initials: WY
authors.lastname: Meng
authors.affiliation: d Peking University Third Hospital , Beijing , China .
authors.forename: Yong-Qing
authors.initials: YQ
authors.lastname: Wang
authors.affiliation: e General Hospital of Beijing Military Region , Beijing , China .
authors.forename: Li-Xin
authors.initials: LX
authors.lastname: Shang
authors.affiliation: f Center Hospital of Aviation Industry , Beijing , China .
authors.forename: Zhen-Yu
authors.initials: ZY
authors.lastname: Cai
authors.affiliation: g Pinggu Maternal and Child Health Hospital of Beijing , Beijing , China .
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Ji
authors.affiliation: h Beijing Hospital of Miyun City , Beijing , China .
authors.forename: Yun-Feng
authors.initials: YF
authors.lastname: Wang
authors.affiliation: i Navy General Hospital , Beijing , China .
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun
authors.affiliation: j Beijing Daxing District Hongxing Hospital , Beijing , China .
authors.forename: Jia-Xiu
authors.initials: JX
authors.lastname: Liu
authors.affiliation: k Beijing Chui Yang Liu Hospital , Beijing , China .
authors.forename: Li
authors.initials: L
authors.lastname: Wei
authors.affiliation: l Peking University Shougang Hospital , Beijing , China .
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Sun
authors.affiliation: m Combined with Traditional Chinese and Western Medicine Hospital of Beijing City , Beijing , China .
authors.forename: Xue-Ying
authors.initials: XY
authors.lastname: Zhang
authors.affiliation: n Beijing No.6 Hospital , Beijing , China .
authors.forename: Tian-Xia
authors.initials: TX
authors.lastname: Luo
authors.affiliation: o Beijing Changping Hospital of Traditional Chinese Medicine , Beijing , China , and.
authors.forename: Hai-Xia
authors.initials: HX
authors.lastname: Chen
authors.affiliation: p General Hospital of Jingmei Group , Beijing , China.
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Yu
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002681:China / Q000453:epidemiology; D016640:Diabetes, Gestational / Q000453:epidemiology; D005260:Female; D006801:Humans; D009765:Obesity / Q000150:complications / Q000453:epidemiology; D050177:Overweight / Q000150:complications / Q000453:epidemiology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D011256:Pregnancy Outcome / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013851:Thinness / Q000150:complications / Q000453:epidemiology; D055815:Young Adult
keywords: GDM; obesity; overweight; pregnancy outcomes