Maternal and perinatal outcomes in pregnant women with BMI >50: An international collaborative study

Stephen J. McCall* (Corresponding Author), Zhuoyang Li, Jennifer J. Kurinczuk, Elizabeth Sullivan, Marian Knight

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Objective To examine the association between maternal BMI>50kg/m2 during pregnancy and maternal and perinatal outcomes. Materials and methods An international cohort study was conducted using data from separate national studies in the UK and Australia. Outcomes of pregnant women with BMI>50 were compared to those of pregnant women with BMI<50. Multivariable logistic regression estimated the association between BMI>50 and perinatal and maternal outcomes. Results 932 pregnant women with BMI>50 were compared with 1232 pregnant women with BMI<50. Pregnant women with BMI>50 were slightly older, more likely to be multiparous, and have pre-existing comorbidities. There were no maternal deaths, however, extremely obese women had a nine-fold increase in the odds of thrombotic events compared to those with a BMI<50 (uOR: 9.39 (95%CI:1.15–76.43)). After adjustment, a BMI>50 during pregnancy had significantly raised odds of preeclampsia/eclampsia (aOR:4.88(95%CI: 3.11–7.65)), caesarean delivery (aOR: 2.77 (95%CI: 2.31–3.32)), induction of labour (aOR: 2.45(95% CI:2.00–2.99)) post caesarean wound infection (aOR:7.25(95%CI: 3.28–16.07)), macrosomia (aOR: 8.05(95%CI: 4.70–13.78)) compared a BMI<50. Twelve of the infants born to women in the extremely obese cohort died in the early neonatal period or were stillborn. Conclusions Pregnant women with BMI>50 have a high risk of inferior maternal and perinatal outcomes.
Original languageEnglish
Article numbere0211278
Number of pages11
JournalPloS ONE
Issue number2
Publication statusPublished - 4 Feb 2019

Data Availability Statement

Data cannot be shared publicly because of because of confidentiality issues. Requests for access to the UK dataset will be considered by the National Perinatal Epidemiology Unit Data Sharing committee. Access to the data can be requested from Access to the Australian data requires an application to the AMOSS steering committee and will require specific ethics committee approval in Australia. Therefore, the terms and conditions of using the Australian data does not give the NPEU the permission to share the Australian data. The authors required approval from the AMOSS steering committee and ethics committee to access the Australian data. The AMOSS committee can be contacted using in the first instance.


  • Body mass index
  • Hypertensive disorders in pregnancy
  • Pregnancy
  • Obesity
  • Medical risk factors
  • Gestational diabetes
  • Labor and delivery
  • Obstetrics and gynecology


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