383. Obese primiparous women undergoing induction of labour have a higher caesarean section rate: An analysis using the Robson 10-group classification system

Abstract

Obesity in pregnant women is rising rapidly, and is associated with increased rates both elective and emergency caesarean sections, the most frequently performed sugical procedure globally, and this has implications on short and long term maternal and perinatal health. To evaluate the effect of maternal obesity on CS rates and identify the key patient categories according to the Robson Ten-Group Classification System (TGCS) contributing to the high CS rates. Retrospective analysis of obese gravidas (BMI > 30 kg/m2) who delivered in our unit from 1 January 2010 to 31 December 2017. Parameters of parity, number of fetuses, fetal presentation, gestational age, type of onset of labour and mode of delivery were collected to form the 10 patient groups. Non-obese gravidas who delivered during the same period were controls. There were 6115 deliveries, with 740 (12.1%) obese. Overall CS rate in the obese group was 42%, compared to 32% in the control group (P < 0.05). The largest contributor to the overall CS rate was Group 5 (term multiparous singelton pregnancies with at least a previous uterine scar). Among the obese with unscarred uteri, Group 2a (term nulliparous singleton cephalic, induced labour) and Group 10 (all singleton women with preterm deliveries) were the top contributors to the overall CS rate. Induced obese primigravida had a higher CS rate (43.5%) compared to induced obese multigravidas (6.9%) (p < 0.05). Maternal obesity is a significant risk factor for CS, with almost 1 in two obese women having a CS. Parity has an important influence on the success of induction of labour in obesity, with primparity conferring a 6-fold increased risk for CS. The high contribution of pretem CS delivery reflects the association of maternal obesity with high risk obstetric complications such as pre-eclampsia, gestational diabetes and fetal growth disorders.