Obesity and the risk of stillbirth - A reappraisal - A retrospective cohort study.

Objective: Studies have noted an inconsistent risk of stillbirth in women with high BMI. There are no reports on obese women specifically selected without any pre-existing or current medical or obstetric conditions. We aimed to document the risk of stillbirth, specifically in this group of women.

Methods: A retrospective cohort study of 182,362 singleton pregnancies at gestation ≥28 weeks in Queensland, Australia between 2008 and 2016 with no pre-existing or current medical or obstetric conditions.

Results: We found no significant association on rates of stillbirth with increasing BMI ; odds ratios for stillbirth were 1.10, 95% CI; 0.90, 1.36 in overweight and 1.09, 95% CI; 0.87-1.37 in obese women compared to women with normal BMI. There was increasing trend in stillbirth from 37 weeks and more specifically after 40 weeks with increasing BMI. Independent of BMI, there was a statistically significant increased risk of stillbirth for women with poor antenatal care and current smokers.

Conclusions: There is no firm evidence for an effect of BMI on stillbirth at ≥28 weeks gestation among women with uneventful pregnancies. Our care should focus on surveillance for early detection and monitoring of co-morbidities associated with obesity with consideration to birthing prior to 40 weeks gestation.