The impact of induced labour on postpartum blood loss

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Abstract
It is generally believed that postpartum blood loss is less in patients whose labour is induced with prostaglandins than in patients delivered without induction. However, postpartum blood loss is known to be greater with precipitate labour and labours induced with oxytocin and prostaglandins, unless an oxytocic agent is continued after delivery. A retrospective study was undertaken at the University Hospital of the West Indies to look at the outcome of induced labour during 3 months, October – December 1998. Misoprostol induction was compared to the outcome after oxytocin induction, misoprostol induction plus oxytocin augmentation and those patients who delivered without oxytocics during this same time period. During that period, 524 patients were delivered and 51 (9.7%) were induced with misoprostol, 174 (33.2%) with oxytocin, 21 (4%) misoprostol plus oxytocin and 271 (51.7%) without oxytocic. Seven patients were eliminated from further analysis, as we were unsure of their induction status. Results showed no significant differences between the groups for variables such as maternal age, parity and fetal birth weight. There was a significantly greater mean blood loss at delivery with all induced labour compared with those not induced. For misoprostol 162.5(SD 190) ml, oxytocin (150 (SD 100) ml and for oxytocin plus misoprostol 150 (SD 150) ml, while controls had the lowest mean blood loss 100 (SD 130) ml occurring where no predelivery oxytocic was needed (P < 0.03). Postpartum haemorrhage was highest with misoprostol 5.8% versus 4.4% for no oxytocic, 1.1% for oxytocin and 0% for misoprostol plus oxytocin. However, none of these values reached statistical significance. The misoprostol group also had the shortest first stage, 333 minutes versus 557 minutes for oxytocin, 576 minutes when both misoprostol and oxytocin was used and 344 minutes with no oxytocic. Blood loss was also independently directly associated with placental weight (P = 0.01) and fetal birth weight (P = 0.03), as well as the length of the third stage of labour (P = 0.01), but not the length of the first stage of labour. Induction of labour with oxytocic agents is associated with greater blood loss. However, increased blood loss is not due to precipitate labour alone.