Patients having Cesarean section after they have been in labor for many hours bleed much more, in average twice as much, as compared with patients having an elective Cesarean section. The investigators believe a simple change in practice might contribute to reduce this bleeding. This study will involve the use of oxytocin (also known as syntocinon), ergonovine (also known as ergot) and carboprost (also known as hemabate). Oxytocin is routinely used to help contract the uterus and keep it contracted after the delivery of the baby and placenta, so as to reduce the amount of blood loss. Ergonovine is also given through the intravenous line, while carboprost is given as an injection in the muscle. Although they are not routinely given in every case, these are very frequently given as rescue medications to patients who fail to respond appropriately to oxytocin. This study is designed to determine if ergonovine or carboprost given in association with oxytocin, in a preventive way, after delivery of the baby and placenta, can reduce the amount of blood loss during Cesarean sections following a trial of labour.

The objective of the investigators study is to compare the efficacy of intravenous ergonovine and intramuscular carboprost, when administered with oxytocin infusion, prophylactically to decrease blood loss at Cesarean section for labor arrest. Desensitization of the oxytocin receptors has been recently demonstrated in cultured human myometrial cells after continuous and prolonged exposure to oxytocin in-vitro. This could be also the reason for a greater risk of uterine atony and postpartum hemorrhage (PPH) seen in women requiring induction and augmentation of labor. Therefore, addition of a different uterotonic agent, involving a different mechanism of action, to oxytocin infusion is likely to be beneficial, especially in women undergoing CS following failure to progress in labor, who are at a greater risk for PPH.

Inclusion Criteria:

• patients who give written informed consent
• patients undergoing Cesarean section for failure to progress in labour, under regional anesthesia
• patients should be in the first stage of labour and have received oxytocin for at least 4 hours

Exclusion Criteria:

• patients who refuse to give written informed consent
• patients who require general anesthesia
• patients who claim allergy or hypersensitivity to oxytocin, ergot derivatives or prostaglandins
• patients with cardiac diseases and hypertension or preeclampsia ( diastolic blood pressure > 90 mmHg, systolic blood pressure > 140 mmHg )
• patients with asthma or any other respiratory disease
• patients with conditions at risk of PPH such as placenta previa, multiple gestation, preeclampsia, macrosomia, polyhydramnios, uterine fibroids, previous history of uterine atony and postpartum bleeding, bleeding diathesis and known infection.