Contact Vicki
If you have any questions or would just like more information please don't hesitate to get in touch by clicking the button below and filling out the contact form.
Contact Vicki
The problem with birthing on your back – and the racist history of pelvic stereotypes
For many women, the default birthing position in hospitals is lying flat on the back. This practice has become so routine that it is rarely questioned, yet it is one of the least effective positions for labour and birth. Sometimes women are placed in a semi-reclining position, which gives the illusion of being “better” because they are not completely flat. In reality, this position can be even more restrictive, as it prevents the sacrum from moving at all, further limiting the natural biomechanics of the pelvis.
In 1598, barber-surgeon Jacques Guillemeau was one of the first men to use the reclining birth position, coinciding with the rise of obstetric equipment and episiotomies.
In 1668, French obstetrician François Mauriceau is often credited with popularising the “horizontal” birth position, not because it benefited the woman, but because it was more convenient for those attending the birth. Mauriceau’s views reflect how pregnancy and birth were beginning to be medicalised in Europe at that time. He even described pregnancy as “a tumour in the belly” that required medical intervention, framing a normal life event as a pathological condition. This shift in thinking laid the foundation for a model of maternity care that prioritised the authority and convenience of physicians over the physiology and comfort of women.
It is also often suggested that the practice of women lying on their backs during birth was influenced by French King Louis XIV in the 17th century. Louis fathered 22 children with his wives and mistresses, and it is said he enjoyed watching them give birth. However, he found it difficult to see the process when women were upright or squatting. To satisfy his own preferences, he ordered attendants to position women flat on their backs in bed, with their legs raised and apart, so he could have a better view of the birth. As with many customs of royalty, what was done in the palace quickly influenced wider society. Over time, this position became fashionable and then normalised, despite being less effective and more uncomfortable for the woman herself. What began as a royal whim was eventually institutionalised in maternity wards, where it remains the default position for many women today – not because it is safer, but because it became habit.
We now know that when women are lying on their back, the natural biomechanics of the pelvis are restricted. The pelvis is not a fixed, rigid bone but a dynamic structure made up of the inlet, mid-pelvis, and outlet. These areas are held together by ligaments that soften during pregnancy under the influence of hormones such as relaxin, allowing the pelvis to expand and become more mobile in labour. This mobility creates space for the baby to navigate through.
When a woman is on her back, however, that mobility is significantly reduced, making the process harder for both mother and baby. It does, however, make it easier for care providers to “see what is going on” – even though this convenience should never be the primary focus.
The sacrum, which is the triangular bone at the base of the spine, plays a crucial role in birth. It forms the back part of the pelvic outlet and is connected to the rest of the pelvis by flexible joints and ligaments.
Mobility matters: During labour, the sacrum can move backward (a motion sometimes called “nutation”) to create more space at the outlet of the pelvis. It is often referred to as the Rhombus of Michaelis.
More room for the baby: This backward movement can add valuable millimetres of space, which can be enough to help the baby’s head rotate and descend more easily.
What happens when it’s blocked: Lying flat or semi-reclining on the sacrum presses it against the bed, preventing it from moving. This reduces the pelvic outlet and can make labour longer, more painful, and more likely to require interventions.
Upright and forward positions: Kneeling, squatting, or hands-and-knees free the sacrum, allow it to move as designed, and optimise the biomechanics of birth.
For decades, women have been told that their pelvis might be “too small” or “the wrong shape” to give birth vaginally. This belief comes from the Caldwell–Moloy Classification developed in the early 1900’s, which divided pelvises into four rigid “types”:
Their research was based on skeletal collections that were not representative of all women and often came from small, biased samples.
They tied these pelvic shapes to racial and ethnic groups, reinforcing the pseudoscientific idea that different races had fundamentally different anatomy that predicted how they would give birth. The gynecoid pelvis was considered “ideal” while the others were labelled as more problematic.
Pelvic typologies are not just outdated; they are rooted in racist and sexist pseudoscience. By teaching and repeating them uncritically, the medical system risks perpetuating harmful stereotypes. The modern, evidence-based approach is to support women’s movement, positioning, and physiology rather than labelling pelvises into categories.
In 2015, a CT-based geometric morphometric study by Kuliukas et al., conducted on women in Western Australia, dismantled the long-held belief in four distinct pelvic types. Their analysis found no clear clustering into gynecoid, android, anthropoid, or platypelloid shapes. Instead, they encountered an amorphous “cloud” of pelvic variation, a finding that casts serious doubt on teaching any rigid typologies in midwifery or medical training.
Female pelvic shape: Distinct types or nebulous cloud?
These typologies are still taught in some midwifery and medical texts today, even though they’ve been widely discredited.
They perpetuate the idea that women’s ability to birth is predetermined by race and bone structure, rather than recognising the adaptability of the pelvis, the role of movement and position, and the influence of care environments.
They risk reinforcing implicit bias in clinicians, who may still (consciously or unconsciously) believe some women are “built for birth” and others are not.
Modern research has shown this thinking to be outdated and misleading because:
Pelvimetry is unreliable: Measuring the pelvis (once done by X-ray and now sometimes by ultrasound) has been found to have little predictive value in determining whether a woman can give birth vaginally. A Cochrane review concluded that pelvimetry should not be used to decide mode of birth, as it often leads to unnecessary caesareans. (Cochrane Database of Systematic Reviews, 2017).
The pelvis is adaptable: With the influence of hormones and the ability of the pelvic joints to move, the pelvis can widen and adjust throughout labour. (World Health Organisation, Recommendations: Intrapartum Care for a Positive Childbirth Experience, 2018).
Babies are adaptable too: The five bones of the baby’s skull are not fused but connected by flexible sutures and fontanelles. This allows the bones to overlap and shift – a process known as moulding – so the head can move through the birth canal. Birth worker and activist Gloria Lemay likens this to a folding steamer tray: just as the small plates overlap and adjust to fit into different sized pots, the bones of the baby’s head fold and accommodate the changing dimensions of the pelvis.
Birth is dynamic, not static: Labour is not about fitting a fixed baby through a fixed pelvis. It is about movement – the baby rotates, the mother shifts positions, and the pelvis opens and closes with remarkable flexibility.
True cephalopelvic disproportion is rare: When it does occur, it is usually influenced more by care practices, mobility, interventions, and systemic inequalities than by pelvic type. (RANZCOG, Intrapartum Care, 2021).
Upright positions support physiologyResearch consistently shows that upright positions, such as squatting, kneeling, standing, or using all fours, benefit labour and birth.
Upright positions can:
Side-lying is also an effective position that protects the perineum while still allowing pelvic movement.
Every woman should have the freedom to move instinctively in labour. Movement and position changes are a powerful way of easing discomfort, creating space in the pelvis, and helping the baby find the best position. Restricting a woman to her back can not only make labour more difficult for most women but also reinforces outdated myths about “small” or “inadequate” pelvises.
The belief that some women simply “don’t have the right pelvis” is a relic of early 20th-century thinking. Combined with the routine of birthing on the back, it has shaped decades of unnecessary intervention and fear. The focus should not be on provider convenience or outdated typologies, but on supporting women in positions that work with their physiology. Birth is most effective when women are free to move, upright or forward-leaning, and encouraged to trust the remarkable adaptability of their bodies.
Trust your body.
Trust your movement.
Birth works best when you are free to move.
References:
RANZCOG. (2021). Intrapartum Care Clinical Guideline.
Pelvises I have Known and Loved – Gloria Lemay
(PDF) Female pelvic shape: Distinct types or nebulous cloud?
The Rhombus of Michaelis – Dr Sara Wickham
If you have any questions or would just like more information please don't hesitate to get in touch by clicking the button below and filling out the contact form.
Contact Vicki