Role of prophylactic oxytocin in the third stage of labor : Physiologic versus pharmacologically influenced labor and birth

Introduction
Maternity care providers administer oxytocin prophylactically to prevent postpartum hemorrhage (PPH). Prophylactic oxytocin is generally considered effective and safe and is promoted by national organizations for standardized use. In this article, the evidence supporting prophylactic oxytocin administration for women undergoing spontaneous labor and birth compared with women whose labors included administration of exogenous oxytocin for induction or augmentation is explored.

Methods
Using data from randomized controlled trials included in 2 recent Cochrane meta-analyses papers, only studies with women in spontaneous labor were selected for inclusion (N = 4 studies). Outcomes of immediate postpartum bleeding volumes (≥ 500 mL or 1000 mL), risk for blood transfusion, and risk for administration of more uterotonic medication were pooled from these 4 studies. Focused random effects meta-analytics were used.

Results
Compared to women without prophylactic oxytocin, women who received prophylactic oxytocin had a lower risk of having a 500 mL or higher blood loss. However, prophylactic oxytocin did not lower risk of PPH (≥ 1000 mL), blood transfusion, or need for additional uterotonic treatment.

Discussion
Prophylactic oxytocin may not confer the same benefits to women undergoing spontaneous labor and birth compared to women laboring with oxytocin infusion. Reasons for this difference are explored from a pharmacologic perspective. In addition, the value of prophylactic oxytocin given recent changes in the definition of PPH from greater than or equal to 500 mL to 1000 mL or more after birth is discussed. Finally, gaps in research on adverse effects of prophylactic oxytocin are presented. More research is needed on reducing risk of PPH for women in spontaneous labor.