The hypothesis underlying this trial is that an increase in oxytocin dose can reduce the rate of caesarean sections in primiparous obese patients, with a spontaneous onset of labour, without increasing maternal or neonatal morbidity. This would be a major step forward in reducing morbidity in an at-risk population and in improving the obstetric prognosis for future pregnancies.~The research is a double-blind controlled trial, including primiparous obese women in spontaneous labour, for whom a prescription of oxytocin is decided. Oxytocin is currently indicated for notably insufficiency of uterine contractions, at the beginning or during labour.The recommended dosage in the market authorization will be used for the control group.~The control group will receive oxytocin at 2 milli-International unit /mL and the intervention group at 4 milli-International unit /mL, controlled by pump (final volume = 500 mL) or electrical syringe (final volume = 50 mL).~The primary objective is to compare the effect of higher doses of oxytocin (intervention group) vs standard doses of oxytocin (control group) on the rate of caesarean sections in obese patients with spontaneous onset of labour.~The secondary objectives will be to compare the effect of higher doses of oxytocin (intervention group) vs standard doses of oxytocin (control group) on maternal and labour complications (length of labour, arrest of labour, interruption of oxytocin perfusion and reason, uterine hyper-stimulation, mode of vaginal delivery, reason for caesarean section, post-partum haemorrhage, maternal blood transfusion, volume of oxytocin infusion, oxytocin side effects), as well as foetal complications and neonatal complications.
The rate of caesarean section is higher among obese pregnant women, leading to increased morbidity in this already vulnerable population. Oxytocin is the main drug used in obstetrics to optimize progress of labour, but observational studies have suggested that its efficiency may be insufficient in obese women with usual doses.~The research is a randomised controlled trial to test the effect of an increased oxytocin dose on the rate of caesarean section in obese primiparous women with spontaneous labour between two oxytocin dosage regimens.