Comparing Forces on the Fetal Neck in Breech Delivery in Lithotomy Versus All-fours Position: A Simulation Model

Abstract 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. +500g, 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.