Photo showing how mum’s bones shift during birth will take your breath away

Posted in Birth.

We know that pregnancy and childbirth change a woman’s body in all kinds of ways, but this photo illustrates one of those transformations in a rarely-seen way.

The Rhombus of Michaelis

Facebook account Tangi Birth Services shared this image and gave some background on what exactly is going on here.

“Can you see that bulge on her lower back? That is the rhombus of Michaelis,” they wrote alongside the amazing photo of a woman labouring.

“During the second stage of labour, a combination of bones including your sacrum actually move backwards and in doing so, increases the diameter of your pelvis. This is what is known as opening of the back.”

They go on to explain that this totally normal physiological phenomenon “allows your baby the maximum amount of space to turn as they navigate their way out into the world.”

To help this ‘opening of the back’ happen, upright or leaning-forward active birth positions are recommended.


Turns out that a woman’s back and pelvic bones are not the only ones that are changing during this stage of birth. 

“Your baby’s head is moulding – changing shape to fit through those pelvic bones! Your body was made to do this! And your body and your baby work together!”

The appearance of the rounded Rhombus of Michaelis – the area of the lower back that bulges during birth – signals to attending midwives or doctors that the baby is descending through the birth canal. 

It was  named after a gent called Gustav Adolf Michaelis who was a 19th-century German obstetrician.

"Can you see that bulge on her lower back? That is the rhombus of Michaelis. During the second stage of labour, a…

Posted by Tangi Birth Services on Thursday, 19 September 2019

Lady lumps

Commenters on this post said this made so much sense to them, and a bunch of women said they actually felt their bones pop open to allow their baby’s passage.

“When my bones shifted for birth I felt a pop like when you crack your knuckles and it felt SOOOOO GOOD!!! I had been having terrible back labor and then POP and just this extremely wonderful release and the pain was gone. So amazing.”

“I had the pop with my last baby and I literally couldn’t even feel my contractions anymore! So grateful!!! Doc said it was normal and watched the screen to see contractions and tell me when to push!”

“Same thing for me!! I delivered my son in this position and felt the pop and immediate relief and baby was here 2 pushes later !! So amazing.”

The Rhombus of Michaelis rises as labor progressing towards the pushing phase. It is the result of the baby's head…

Posted by Human Birth Project on Friday, 28 July 2017


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