Association of the Length of the Third Stage of Labor and Blood Loss Following Vaginal Delivery.

OBJECTIVES: The length of the third stage of labor is correlated with blood loss following a vaginal delivery. We aimed to accurately measure blood loss following a vaginal delivery and examine the relation between blood loss and length of the third stage of labor.

METHODS: This was a prospective observational study of singleton pregnancies ≥24 weeks undergoing a vaginal delivery. Blood loss was meticulously measured and the length of the third stage of labor was recorded.

RESULTS: The median blood loss of the 600 women was 125 mL (interquartile range 175) and the median length of the third stage of labor was 5 minutes (interquartile range 4). Total blood loss ( P = 0.0263) and length of the third stage of labor ( P = 0.0120) were greater in pregnancies ≥37 weeks versus <37 weeks. Women with a third stage of labor ≥15 minutes had a significantly greater risk of blood loss >500 mL (relative risk 5.8, 95% confidence interval 8.36-29.88).

CONCLUSIONS: The median blood loss following a vaginal delivery is 125 mL and the median length of the third stage of labor is 5 minutes. Total blood loss and the length of the third stage of labor are greater in pregnancies >37 weeks. Women with a third stage of labor >15 minutes are 15.8 times more likely to have total blood loss ≥500 mL. As such, it is prudent to consider manual extraction of the placenta at 15 minutes rather than 30 minutes to minimize the risk of excessive blood loss.