Incredible photo shows how mum’s bones shift during birth

Just when you thought the female body couldn’t be any more incredible, along comes a photo to blow your mind a little more.

The photo we’re talking about was shared by the North Dallas Doula Associates on Instagram, and it shows a mum’s bones moving during labour. 

The proper term for the bulge, which can appear during the second stage of labour, is the rhombus of Michaelis – AKA the kite-shaped area of the lower spine that includes the sacrum and three lower lumbar vertebrae.

Resharing the image, the Mother Down Under – Hypnobirthing Australia and Postnatal Specialist Facebook page explains things further.

“Can you see that bulge on her lower back? That is the rhombus of Michaelis,” the page says.

“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 the ‘opening of the back.'”

Pretty incredible, right?

“Very fast delivery”

Although the photo was originally shared last year, it’s still very relevant for women giving birth today because it gives mums a visual representation of one of the many ways the body works with them during birth.

Speaking to Mom.com, Melissa Espey-Mueller, the owner and director of North Dallas Doula Associates says listening to your body can make a huge difference.

“This mom is on her knees facing and leaning over the head of the bed to allow her the ability to not bear all her weight on her legs,” Melissa explains.

“If she was lying on her back, this entire area would have been closed off, and it would have prevented her baby from descending as easily, and made the transition and pushing phase longer,” she says. “Since she was able to listen to her body and communicate her feelings to me, I was able to suggest this position which allowed for a very fast delivery.”

Rhombus of Michaelis can only move in certain positions

In a paper titled Birth without active pushing: A physiological second stage of labour, midwife Jean Sutton echoes what Melissa says about birth positions.

“This movement [the rhombus of Michaelis] can only occur if the mother is in a position that puts her weight in front of her ischial tuberosities, with the angle between her spine and her thighs at least 120° (i.e. the distance between her hips and her head is less than the distance between her knees and her head),” she writes. 

Why does the rhombus of Michaelis movement occur?

Jean says the movement appears to occur when the back of the baby’s head contacts a nerve plexus at the front of the pelvis, triggering “the backward movement of the rhombus of Michaelis and the fanning open of the wings of the ilia, which makes more space in the pelvic cavity.”

Signs the rhombus of Michaelis is moving

As mentioned above, the opening only occurs in certain birthing positions. But Jean says there are sure-fire signs it’s happening:

• the mother reaches to grab hold of something above her
• her body sags forwards and her “knees roll out”
• her back arches and she instinctively wriggles her lower body
• the uterus contracts, moving the baby body’s down.

A lot of changes happen during childbirth, and the above image is just further proof of what we already know – the female body is remarkable. 

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Read more:

• 10 powerful photos show what birth is really like
• Preparing for birth: what a midwife wants you to know right now
• Pregnant? Here’s a rundown on the 5 most common ways to give birth