Comparing forces on the fetal neck in breech delivery in lithotomy versus all-fours position: a simulation model

Arch Gynecol Obstet. 2023 Jul;308(1):91-99. doi: 10.1007/s00404-022-06671-5. Epub 2022 Jul 20.


Purpose: To measure forces applied to the fetal neck, in a simulation model for breech delivery, in both lithotomy versus all-fours position.

Methods: We used a Laerdal SimMom simulator and a Birthing Baby together with PROMPT Flex Software. The descent of the fetus was accomplished using the Automatic Delivery Module 2. The baby was always in breech position; the SimMom in either all-fours or lithotomy positions. Sensors were located inside the fetal neck region to simulate forces applied to the plexus.

Results: The lowest force on the fetal neck region was recorded for the delivery in all-fours position without further maneuvers (mean force 58.70 Newton, standard deviation 2.54 N). As weight was added to the baby, the force increased (i.e. + 500 g, mean force 71.8 N, SD 3.08 N, p < 0.001). Delivery in lithotomy position resulted in a mean force of 81.56 N (SD 19.55 N). The force significantly increased in case of delivery of the head without assistance from contractions (mean force 127.93 N, SD 23.10 N). In all-fours position, the delivery of the fetal head from pelvic floor level without contractions (Frank's Nudge maneuver) resulted in a mean force of 118.45 N (SD 15.48 N, p = 0.02). Maneuvers for shoulder dystocia (the inverted type that can occur during breech delivery) led to significantly higher mean forces independent from birthing positions.

Conclusion: Breech delivery in all-fours position was associated with the lowest force acting on the fetal neck in our simulation model.

Keywords: All-fours position; Brachial plexus; Breech delivery; Lithotomy position; Simulator; Spontaneous vaginal breech delivery.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breech Presentation* / surgery
  • Delivery, Obstetric / methods
  • Dystocia* / surgery
  • Female
  • Fetus / surgery
  • Humans
  • Parturition
  • Pregnancy
  • Shoulder Dystocia*