the mode trial: planned caesarean section versus induction of labour for women with class iii obesity

Conditions: Obesity Complicating Childbirth; Obesity; Labor Onset and Length Abnormalities; Pregnancy, High Risk; Cesarean Section Complications

Summary: canadian guidelines recommend that women with a pre-pregnancy body mass index (bmi) at or above 40 kg/m2 deliver by their due date. when delivery is planned prior to spontaneous labour, there are two options: planned induction of labour or pre-labour caesarean (c-section). however, it is not yet clear whether induction of labour or planned pre-labour c-section is the best option for this population. the mode trial aims to assess the feasibility of conducting a larger-scale trial of planned mode of delivery in first time mothers who have a bmi \>=40kg/m2, and obtain preliminary data on health outcomes for moms and babies following delivery by either planned c-section or induction of labour.

women with obesity have a decreased likelihood of achieving vaginal delivery. according to the centre for maternal and child enquiries, the chance of spontaneous vaginal delivery in women with a bmi ≥35kg/m2 is 55%, while the chance is 36.7% in women with a bmi ≥40.0kg/m2. this number includes women who go into labour spontaneously, in which, the odds of a vaginal delivery are highest. the rate of failure to induce labour approaches 80% with increased complications and morbidity including abnormal fetal heart rate monitoring, labour dystocia, emergency c-section, and fetal macrosomia. it has been proposed that some women may benefit from a planned caesarean section delivery. however, caesarean sections are also not straightforward in women with obesity, and come with significant risks of short- and long-term morbidity for mother and baby, including prolonged operative times, higher volumes of blood loss and infection rates and higher rates of nicu admission. given that there are many considerations when deciding how to best deliver a woman with obesity, it is not surprising that there is a high degree of clinical equipoise. in reality, the decision is made jointly between the patient and her care provider, often guided by overall instinct and local resource availability. studies to date have been retrospective in nature. there is a significant need for prospective study of the outcomes and experiences of planned induction of labour and planned caesarean section in women with obesity to allow evidence-based counselling and decision-making.

Eligibility criteria:
inclusion criteria: * capability of participant to comprehend and comply with study requirements * age ≥18 years at time of consent * nulliparous (never given birth after 19+6/7 weeks of gestation) * pre-pregnancy bmi or calculated bmi obtained in the first 13 weeks of pregnancy ≥40kg/ m2 * participant plans to give birth in a participating site * gestational age 34+0/7 - 36+6/7 weeks (based on estimated date of conception (edc) assigned at the first ultrasound performed after 7+0/7 and prior to 20 +0/7 weeks) * live fetus, documented positive heart rate at visit 1 prior to randomization * singleton fetus in cephalic presentation at the time of randomization * no maternal or fetal contraindications to vaginal delivery exclusion criteria: * known major fetal anomaly, confirmed by ultrasound or genetic testing * multiple gestation * known documented evidence of alcohol or drug abuse in this current pregnancy * currently enrolled or has participated in another clinical trial within 3 months of the date of randomization (at discretion of trial coordinating centre)

Keywords: obesity pregnancy labour labor caesarean cesarean c-section induction