Hip extension at crowning doesn't reduce perineal tears in first-time moms, study finds

Researchers hoped a simple leg-lowering maneuver during vaginal delivery could spare first-time mothers from painful perineal tears — but a large randomized trial suggests it's not that straightforward. The study, published in Obstetrics & Gynecology, enrolled 1,206 nulliparous women at a Boston tertiary care center and found no significant difference in perineal lacerations (second-degree or higher) between women who extended their hips at crowning (66.6%) versus those who kept them flexed in the usual position (66.2%).

Rates of obstetric anal sphincter injuries were also similar between groups. Notably, 25% of women assigned to the hip-extension group ended up delivering with hips flexed — often those with longer labors or operative deliveries — complicating the interpretation of results.

By the Numbers:

• 66.2% vs. 66.6% — rate of significant perineal lacerations (usual care vs. intervention; P = .89)
• 8.0% vs. 8.3% — obstetric anal sphincter injury rates (P = .86)
• Adjusted odds ratio of 0.77 (P = .03) for higher-order lacerations in the as-treated hip-extension group

Why it matters: While the primary trial result was neutral, ordinal analyses suggest hip extension may reduce the severity of perineal trauma. Researchers believe a larger, more adherent study — focused on spontaneous deliveries — could clarify whether this low-cost positioning maneuver has a meaningful role in protecting birthing patients.