Efficiency of the modified Sims maternal position in the rotation of persistent occiput posterior position during labor: A randomized clinical trial

Birth. 2018 Dec;45(4):385-392. doi: 10.1111/birt.12347. Epub 2018 Mar 14.


Background: Fetal occiput posterior position in labor is associated with more painful and prolonged labor, and an increase in both maternal and fetal morbidity. The aim of this study is to assess whether the modified Sims position on the side of the fetal spine increases the rotation to occiput anterior position in women with epidural analgesia and a fetus in persistent occiput posterior (POP) position.

Methods: This is an open, randomized controlled, clinical trial. One hundred and twenty women in labor with fetuses in POP position were included. The diagnosis was performed through digital vaginal examination and confirmed with an ultrasound scan. Women were randomized into the free position group or the modified Sims on the side of the fetal spine. The primary outcome was rotation to occiput anterior, and secondary outcomes were type of delivery, postpartum perineal condition, perinatal results, and maternal satisfaction.

Results: In pregnant women undergoing labor in the Sims position, fetuses in POP rotated to occiput anterior in 50.8% of cases, whilst in the free position group, the rotation occurred in 21.7% (P = .001). The rate of vaginal deliveries was higher in the Sims group compared with the free position group (84.7% vs 68.3%, P = .035).

Discussion: The modified Sims position is a maternal posture intervention efficient in POP rotation, which decreases cesarean delivery rate. It is a simple and noninvasive intervention, reproducible, and well tolerated by pregnant women.

Trial registration: ClinicalTrials.gov NCT02209090.

Keywords: delivery; fetal occiput posterior position; labor; maternal postures.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Analgesia, Epidural
  • Delivery, Obstetric / methods
  • Delivery, Obstetric / statistics & numerical data*
  • Female
  • Head / diagnostic imaging
  • Humans
  • Labor Presentation*
  • Obstetric Labor Complications / diagnostic imaging*
  • Patient Positioning*
  • Posture*
  • Pregnancy
  • Rotation
  • Spain
  • Ultrasonography, Prenatal
  • Version, Fetal / methods
  • Young Adult

Associated data

  • ClinicalTrials.gov/NCT02209090