A study to compare the effectiveness of intravenous oxytocin with intramuscular oxytocin given at the third stage of labour at preventing bleeding at vaginal birth

INTERVENTION: Participants will be randomised into one of two study arms: Arm one: Participants will receive 1ml 10IU oxytocin intramuscularly and 1ml 0.9% normal saline as placebo intravenously immediately after the delivery of the baby and before the delivery of the placenta at vaginal delivery. Arm two: Participants will receive 1ml 10IU oxytocin intravenously and 1ml 0.9% normal saline as placebo intramuscularly immediately after the delivery of the baby and before the delivery of the placenta at vaginal delivery. The blood loss following normal vaginal delivery will be measured using gravimetric method. The blood loss would be estimated by weighing all the soiled materials on a scale and subtracting the known weights of these materials to determine the blood loss. For women who have an assisted vaginal delivery, Comfy Guard ® (a surgical drape with a pouch for collecting vaginal blood loss) will be placed under the woman’s buttocks in preparation for birth and before delivery of the placenta. The blood collected in the drape will be transferred to a measuring jar with calibrations. Blood‐soaked swabs and drapes will be weighed and the known dry weight of the swabs and drapes will be subtracted. This volume will be added to the measured blood volume from the drape.The measured blood loss is recorded in the participant’s medical notes by the attending midwife. Maternal vital signs will be measured after delivery and before transfer to the postnatal ward, which are recorded in the medical notes. The occurrence of side effects will be recorded using an observation form. Follow‐up: A full blood count will be performed at day 1 after delivery to assess haemoglobin and haematocrit. Data will be collected in duplicate on a case report form (CRF) by reviewing patient’s/participant’s medical notes after the delivery and prior to discharge from the hospital. CONDITION: Postpartum haemorrhage following vaginal delivery ; Pregnancy and Childbirth ; Postpartum haemorrhage following vaginal delivery PRIMARY OUTCOME: Incidence of primary postpartum haemorrhage (> 500ml) following intramuscular oxytocin compared with intravenous oxytocin is determined by reviewing participant’s medical notes and data collected in a case report form (CRF) 24 hours post‐delivery. INCLUSION CRITERIA: 1. Aged 18 or over 2. Female participants only 3. Singleton pregnancy at more than 36 weeks gestation 4. Those anticipated to have a vaginal delivery SECONDARY OUTCOME: 1. Incidence of side effects following administration of oxytocin (headache, vomiting) is determined by reviewing an observation sheet that the attending midwife are required to fill within 30 minutes of delivery and oxytocin administration. The vital signs which are taken after delivery and prior to transfer to the postnatal ward are recorded in the medical notes. Occurrence of hypotension, tachycardia are recorded in the CRF by reviewing the medical notes.; 2. Estimated mean blood loss and early lochial loss is determined by reviewing participant’s medical notes; 3. Incidence of major obstetric haemorrhage (measured blood loss = 1000ml) is determined by reviewing participant’s medical notes 24 hours post‐delivery; 4. Objective change in haemoglobin and haematocrit is measured using a full blood count before delivery and 24 hours after delivery; 5. Incidence of severe anaemia (Hb fall = 20%) is measured using a full blood count before delivery and 24 hours after delivery; 6. Need for blood transfusion and/or blood products is determined by reviewing the participant’s medical notes 24 hours post‐delivery; 7. Postnatal length of stay in labour ward/HDU and in the hospital is determined by reviewing participant’s medical notes; 8. Need for an additional uterotonic agent between the two groups is determined by reviewing the participant’s medical notes 24 hours post‐delivery