Jean Sutton and the Rhombus of Michaelis
A kite-shaped area of the lower back which plays a key role in physiological birth.
Jean Sutton described the rhombus of Michaelis (AKA quadrilateral of Michaelis) as a kite-shaped area that includes the three lower lumber vertebrae, the sacrum and that long ligament which reaches down from the base of the scull to the sacrum. During the second stage of labor, this area of bones moves backwards and as it moves back it pushes the wings of the ilea out, increasing the diameters of the pelvis.
As this occurs, the mother will instinctively
– Move her hands trying to grab or find something to hold onto for support. Sometimes they grab the “monkey bars” provided by some hospitals or the ropes hanging from strengthened parts of the ceiling.
– Spread her knees and let her belly sag.
– Move her head to the back, arching her back and wriggle her lower body
This is known as the Fetus Ejection Reflex, which is bringing the baby down.
It’s what Sheila Kitzinger (1993) who recorded Jamaican midwives saying the baby will not be born “till the woman opens her back.” I’m sure that they were referring to when the woman was opening her back.
A lump appears on the lower back, as the woman leans forward, upright, or on their hands and knees. It can also be felt in the woman’s back as it moves. The rhombus comes out just as second stage starts, and it’s gone back in again by the time that the baby’s feet are born. This happens because the baby head push the sacrum backwards.
Ways the opening of the Rhombus of Michaelis can be prevented
Examples by Jean Sutton:
- If women are on their back with their legs up, then their strong gluteal muscles prevent the rhombus from moving backwards.
- If a woman has her hands behind her knees and is pulling her legs up towards her tummy, the rhombus is also prevented from moving.
- If she’s got an epidural in, the nerve supply is interfered with so that the impulse for it to happen is obstructed.
- Short second stage of labor = let Rhombus of Michaelis open
- Get the woman off the bed
- During second stage of labor do not let anyone move her legs
- Epidurals get in the way of a spontaneous second stage and vaginal birth