Operative vaginal delivery as an independent risk factor for maternal postpartum infectious morbidity

A recent study from the United Kingdom suggested that a single dosage of adjunctive amoxicillin/clavulanic acid with operative vaginal delivery reduces maternal infectious morbidity by 40% (from 19% to 11%). However, 89% of their study population received an episiotomy.

This study aimed to evaluate whether operative vaginal delivery is an independent risk factor for composite maternal postpartum infectious morbidity in a population with a low episiotomy rate.

This was a retrospective cohort study of patients with viable singleton vaginal deliveries after ≥34 weeks gestation at a single perinatal center (2013-2018). The patients were categorized by the mode of delivery: spontaneous vaginal delivery or operative vaginal delivery (forceps or vacuum-assisted). The primary outcome was a composite of maternal infectious morbidity up to 6 weeks after delivery, defined as (1) endometritis, (2) perineal wound morbidity (infection, breakdown, or dehiscence), or (3) culture-proven urinary tract infection. The patient characteristics and outcomes were compared between the groups using appropriate tests. Multivariable models were used to estimate the association between operative vaginal delivery and study outcomes compared with spontaneous vaginal delivery, with adjustment for selected confounders.

Of 14,647 deliveries meeting the inclusion criteria, 732 (5.0%) were operative vaginal deliveries: 354 (48%) forceps and 378 (52%) vacuums. Overall, 210 (1.4%) patients developed the morbidity composite. Patients having an operative vaginal delivery were more likely to be nulliparous, have labor inductions, develop intrapartum chorioamnionitis, receive an episiotomy, and sustain a third- or fourth-degree laceration. After adjusting for confounding factors, no significant association was observed between operative vaginal delivery and composite morbidity (adjusted odds ratio, 1.4 [0.8-2.4]) or any of its individual components. Administration of postpartum antibiotics and documented fever were also similar between groups. There was also no significant association between instrument (forceps vs vacuum) and the maternal infection composite.

In this single-center US cohort, operative vaginal delivery was not an independent risk factor for maternal composite postpartum infectious morbidity.