Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

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 publication




Journal article


PLoS One

Publication Date





Adult, Body Mass Index, Cesarean Section, Cohort Studies, Eclampsia, Female, Fetal Macrosomia, Humans, Labor, Induced, Obesity, Morbid, Odds Ratio, Pre-Eclampsia, Pregnancy, Pregnancy Outcome, Premature Birth, Risk Factors, Stillbirth