ArticleProceedings of the National Academy of Sciences of the United States of America2021
Biomechanical trade-offs in the pelvic floor constrain the evolution of the human birth canal.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. Cited by 21 papers.
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Who cites it
21 citing papers in PubMed, 40 citations in OpenAlex.
- Humans are not unique: difficult birth is common in placental mammals.Biological reviews of the Cambridge Philosophical Society · 2026Review
- Insights into Neanderthal development, childbirth, and locomotion from the Palomas and Dederiyeh pelves.Proceedings of the National Academy of Sciences of the United States of America · 2026Article
- Organ Size and Metabolic Rate Co-Vary with Dimensions of the Obstetric Pelvis: The Metabolic Coordination of Childbirth Hypothesis.American journal of biological anthropology · 2026Article
- Testing the limits: the impact of extreme functional hip width on the muscular demands of walking.Biology open · 2026Article
- Exploring Pelvic Changes: Do Pregnancy and Birth Leave Scars?American journal of biological anthropology · 2026Article
- Advanced FE simulation coupled with statistical surrogate modeling toward a multifactorial view on the pelvic floor muscle damage and perineal tearing during childbirth.Medical & biological engineering & computing · 2026Article
- An evolutionary genomic perspective on preterm birth, genome editing, and pregnancy in the human species.Frontiers in genome editing · 2026Review
- Development and Simulation-Based Validation of Biodegradable 3D-Printed Cog Threads for Pelvic Organ Prolapse Repair.Materials (Basel, Switzerland) · 2025Article
- Finite element modeling in obstetrics and gynecology: advances, applications, and challenges.Frontiers in medicine · 2025Review
- Reconsidering the developmental origins of adult disease paradigm: The 'metabolic coordination of childbirth' hypothesis.Evolution, medicine, and public health · 2024Review
- There is an obstetrical dilemma: Misconceptions about the evolution of human childbirth and pelvic form.American journal of biological anthropology · 2023Review
- The variation in shape and thickness of the pelvic floor musculature in males and females: a geometric-morphometric analysis.International urogynecology journal · 2023Article
- Article
- Transperineal pelvic floor ultrasound for assessing posterior pelvic injury and prolapse in postpartum women.American journal of translational research · 2023Article
- Human shoulder development is adapted to obstetrical constraints.Proceedings of the National Academy of Sciences of the United States of America · 2022Article
- One step further in biomechanical models in palaeontology: a nonlinear finite element analysis review.PeerJ · 2022Review
- Squatting, pelvic morphology and a reconsideration of childbirth difficulties.Evolution, medicine, and public health · 2022Article
- The evolution of pelvic canal shape and rotational birth in humans.BMC biology · 2021Article
- The obstetrical dilemma hypothesis: there's life in the old dog yet.Biological reviews of the Cambridge Philosophical Society · 2021Article
- Biomechanical trade-offs in the pelvic floor constrain the evolution of the human birth canal.Proceedings of the National Academy of Sciences of the United States of America · 2021Article
Corrections and comments
- Erratum issued
Authors and funding
4 authors at 3 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Compared with most other primates, humans are characterized by a tight fit between the maternal birth canal and the fetal head, leading to a relatively high risk of neonatal and maternal mortality and morbidities. Obstetric selection is thought to favor a spacious birth canal, whereas the source for opposing selection is frequently assumed to relate to bipedal locomotion. Another, yet underinvestigated, hypothesis is that a more expansive birth canal suspends the soft tissue of the pelvic floor across a larger area, which is disadvantageous for continence and support of the weight of the inner organs and fetus. To test this "pelvic floor hypothesis," we generated a finite element model of the human female pelvic floor and varied its radial size and thickness while keeping all else constant. This allowed us to study the effect of pelvic geometry on pelvic floor deflection (i.e., the amount of bending from the original position) and tissue stresses and stretches. Deflection grew disproportionately fast with increasing radial size, and stresses and stretches also increased. By contrast, an increase in thickness increased pelvic floor stiffness (i.e., the resistance to deformation), which reduced deflection but was unable to fully compensate for the effect of increasing radial size. Moreover, larger thicknesses increase the intra-abdominal pressure necessary for childbirth. Our results support the pelvic floor hypothesis and evince functional trade-offs affecting not only the size of the birth canal but also the thickness and stiffness of the pelvic floor.
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