Maternal and neonatal outcomes of occiput posterior vaginal delivery.

Aim: The occiput posterior (OP) position is the most common fetal malposition associated with poorer maternal outcomes compared to the occiput anterior (OA) position. However, there are no equivalent reports for women in Japan. This study aimed to investigate the maternal and neonatal outcomes of OP delivery in Japan.

Methods: This retrospective study was conducted at a tertiary hospital in Japan. Singleton pregnant women who delivered vaginally at and after 37 weeks of gestation between January 2000 and May 2023 were included. Participants were divided into OA and OP groups and pregnancy outcomes were compared. Multivariable analysis was performed to adjust for background.

Results: In total, 13 852 eligible participants were divided into OA (13 633, 98.4%) and OP (218, 1.6%) groups. Maternal weights were significantly higher in the OP group than in the OA group, but there were no significant differences in maternal age, height, BMI, and parity. The incidence of assisted vaginal delivery (6.0% vs. 25.2%, adjusted odds ratios [aOR] 6.97), third- or fourth-degree perineal laceration (0.9% vs. 2.8%, aOR 3.52), postpartum hemorrhage (4.3% vs. 8.7%, aOR 2.17), and prolonged second stage of labor (11.3% vs. 29.4%, aOR 4.75) were significantly higher in the OP group. On the other hand, there were no significant differences in neonatal outcomes.

Conclusion: The present study showed that OP vaginal deliveries require more time, and the increased number of assisted vaginal deliveries resulted in more maternal lacerations and hemorrhage. Maternal complications should be noted in the management of OP deliveries.