Tangi Birth Services in Louisiana took to Instagram to share the image which depicts the soon-to-be mother preparing to give birth with her back towards the camera.
If you look closely, her lower back shows a huge bulge pushing against her skin.
“The rhombus of Michaelis (sometimes called the quadrilateral of Michaelis) is 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,” the caption explains.
“This wedge-shaped area of bone moves backwards during the second stage of labour and as it moves back it pushes the wings of the ilea out, increasing the diameters of the pelvis.”
According to the post, in order to give birth women need “to allow the rhombus of Michaelis to move backwards to give the baby the maximum amount of space to turn his shoulders in”.
The image surprised a large number of followers who have given birth before themselves with some now understanding why their backs hurt so much during the process.
“And that dear ladies is why our backbones hurt after giving birth... who knew?” one commented.
A second wrote, “Wow! This is amazing I didn’t know this. But now that it has been brought to my attention I can relate!”
Others took to the post to celebrate the power and strength of the human body.
“Pictures like this make me teary-eyed,” one Instagram user wrote. “The support she has looks incredible with everyone intently watching and letting mama do work HER way.”
“Honestly keep going back to look at this... our bodies are amazing!” a second added. “I remember that impulse to pull on something too... so crazy!!!”
A third simply wrote: “How amazing are our bodies?”