LAUSR

Abstract Morbid obesity and prolonged pregnancy are independently associated with adverse delivery and perinatal outcomes. We conducted a retrospective observational study on otherwise uncomplicated women with a body mass index (BMI) ≥ 40 kg/m2 where, having reached term, induction of labour (IOL) was planned, to prevent prolonged pregnancy. The primary aim was to describe delivery outcomes and short-term maternal and perinatal adverse events. Of 117 cases included, 69 (59%) laboured spontaneously before the induction date, while 48 (41%) required an IOL. Of 48 patients that underwent an IOL, 22 (45.8%) achieved vaginal delivery, compared to 55 (79.7%) who laboured spontaneously (p = <.001). Twenty-two (18.8%) of the 117 babies weighed more than 4000 g, with 13 of these delivered vaginally. Overall, term patients with morbid obesity who laboured spontaneously before requiring induction, had a high rate of vaginal delivery. However, when IOL was required, the rate of caesarean delivery rose dramatically. Impact statement What is already known on this subject? Morbid obesity and prolonged pregnancy are independently associated with adverse delivery and perinatal outcomes. Induction of labour (IOL) increases the workload in busy units. What do the results of this study add? These results help inform accurate counselling on delivery outcomes, which is integral to respectful care, for the continuously increasing numbers of morbidly obese pregnant women. What the implications are of these findings for clinical practice and/or further research? It is preferable to avoid semi- or urgent caesarean deliveries in morbidly obese women after IOL. The outcomes of earlier induction of labour from 39- or 40-weeks’ gestation requires investigation. Earlier induction may reduce the numbers of caesarean deliveries for abnormal cardiotocograph during the process.