Association between total oxytocin dose and maternal and neonatal morbidity during labour induction: a retrospective...

Oxytocin is one of the most widely used treatments in obstetrics. French guidelines favour low-dose protocols to avoid excessive uterine activity. Therefore, there is no recommendation for the maximum total dose to be administered. Several investigations exist about oxytocin dosage during spontaneous labour and induction. They have rarely reported total doses or analysed their association with maternal and neonatal factors.

We assessed the association between cumulative doses of oxytocin and maternal complications such as post-partum haemorrhage and emergency cesarean in the context of labour induction. We conducted an observational, retrospective, monocentric study in a tertiary care centre. We recruited single pregnancies with induction of labour and oxytocin administration during labour at term. The exclusion criteria were previous cesarean and foetus with identified pathology requiring immediate post-partum transfer. We recorded socio-demographic characteristics, obstetrical and neonatal data.

In all, 3598 women receiving induction of labour after 37⁺⁰ WG were recorded. After equivalent sampling over four years, 504 patients were included. Increasing total dose of oxytocin was associated with a greater risk of cesarean and post-partum haemorrhage. Excess risk of cesarean was found from 5 IU of oxytocin (cumulative dose). Nulliparous patients and those who had undergone cervical ripening had a greater risk of morbidity. We found no association with neonatal morbidity factors.

This study alerts to potential morbidity at oxytocin cumulative doses of 5 IU or greater, and so more likely at 10 IU, administered during induction of labour. Obstetric considerations and decisions should be guided by the co-factors of morbidity, in particular parity and need for cervical ripening.