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  • See How Women's Bones Move to Make Way For Baby During Childbirth!

    Women’s bodies are designed to sustain a new life and endure childbirth! It’s amazing!
    by Rachel Perez . Published Oct 10, 2019
See How Women's Bones Move to Make Way For Baby During Childbirth!
  • Women’s bodies are capable of many things—two of them are pregnancy and childbirth.

    When you’re pregnant, your organs in your abdomen move around to make more room for your growing uterus. This visual tool shows how the organs are cramped so the baby can grow unrestricted.

    During childbirth, a woman’s cervix dilates up to ten centimeters so the baby can pass through the birth canal. But it’s not only her pelvis that opens up — bones in her lower back also literally move and to make more room for the baby.

    Need proof? This incredible photo perfectly captured it. Warning, though: it may be a bit graphic. (But that’s childbirth, right?)

    The photo, taken and shared by North Dallas Doula Associates on Instagram, features an unidentified birthing woman on her knees, holding on to the elevated part of the hospital bed as she pushes her baby out. On her lower back, just above her gluteal cleft (butt crack), is a small diamond-shaped lump that isn’t usually there.

    That lump is the body’s “rhombus of Michaelis,” named after its shape. It’s also sometimes called the “quadrilateral of Michaelis,” according to midwife Jean Sutton, from New Zealand, who re-discovered it when she read old midwifery texts.

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    What is the rhombus of Michaelis

    The rhombus of Michaelis is composed of the three lower lumbar vertebrae, the sacrum, and that long ligament, which reaches down from the base of the skull to the sacrum.


    The lumbar vertebrae are part of the body’s spine, located on the lower back. The sacrum is a triangular bone that consists of five segments fused together, also in the lower back between two hip bones of the pelvis.

    “This wedge-shaped area of bone moves backward during the second stage of labor, and as it moves back it pushes the wings of the ilia (the uppermost part of the largest part of the hip bone),” Sutton explained in her theory of 0ptimal fetal positioning.

    In a spontaneous vaginal birth, the baby’s ideal position is head-down, facing the mother’s spine. As the pregnant woman is actively pushing, the baby’s head “presses against the rhombus of Michaelis’s nerves, causing them to contract and ‘open her back’ slightly,” as explained in Birthworks International, a group that conducts training programs in childbirth education.

    The bone movement increases the diameter of the pelvis, by about one to three inches, and gives the baby more room to pass through the birth canal. The slightly bigger opening helps make the birth quick and easy for the mom.

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    See how a birthing mom’s lower-back bones move

    To get a glimpse of a woman’s rhombus of the Michaelis, it’s usually pops out when the woman’s hands reach upwards to find something to hold onto because her pelvic area is going to be destabilized. Her head goes back, and her back arches.

    “You may suddenly see the mother grasp both sides of the back of her pelvis as the ilia are pushed out, and she is suddenly aware of those muscles that have never been stretched before,” Sutton wrote.

    People present at birth will only see the diamond-shaped lump when the birthing woman is leaning forward, upright, or on their hands and knees. (See more labor and birthing positions here.) Lying on the back with knees pulled up restricts the movement of the sacrum, and women who opted for an epidural will not experience this.

    “My husband told me about this! I gave birth on my knees, and he said the base of my back pushed out. Fascinating to see a photo of it,” one woman shared. Another woman realized why, for hours when she was giving birth, she didn’t want to shift to any other labor position other than what was shown in the photo.


    Blink, and you might miss it! The rhombus of the Michaelis can be seen only for a matter of minutes. “It’s back in again by the time that the baby’s feet are born -- in fact, sometimes more quickly than that,” Sutton said. Women’s bodies are simply amazing!

    Read more stories about labor and childbirth here.

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