Squished Part 1: What is the Obstetrical Dilemma?

In this four-part series, I am drawing on decades of research to discredit the pernicious myth of the Obstetrical Dilemma. In this first part, I uncover the racist, misogynistic roots Obstetrical Dilemma and it’s grave consequences. In part two, I take on the skeletal side of the theory, namely women’s pelvises and the skull of the infant, the combination of which is also referred to as fetopelvic morphology, to show that the pelvis isn’t a constraint to fetal growth or bipedal efficiency. In part three, I move on to infant development at birth to dispel the idea that human infants are born prematurely. And finally, in part four, I explain how the infant carrier has influenced the shape (literally) of the modern human by providing support for poorly clinging big headed hominids long before modern humans were on the scene.

Racist Roots with a side of Misogyny

The Obstetrical Dilemma hypothesis posits that the human pelvis is narrow for bipedal efficiency so human infants have to be born prematurely in order to fit–and even with women’s wider and less efficient pelvises, it’s still a huge struggle, often impossible. The hypothesis came into being around the same time that hospital birth was becoming the norm in the United States. In 1949, Aldoph H. Schultz from the John Hopkins University School of Medicine in Baltimore, Maryland published a paper titled Sex Differences in the Pelves of Primates about the pelvic measurements of a variety male and female cadavers from a selection of primate species. Among these non-human primate species are chimpanzees, gorillas, and negroes. Yes. Schultz was working under the misapprehension that black people were a different species of primate, describing their pelvic measurements as more animalistic than whites, as a means of explaining why they had easier births.

Context is king and the context of the time was Jim Crow laws. Segregation was the law and lynchings were rampant. Schultz research justified the lack of medical care available to pregnant black women. There are many reasons beyond pelvic width and fetal size that a woman may want or need access to a hospital before, during, or after birth and black women had few or no options. An article published the same year as Schultz’s show that less than 10% of babies born to black mothers took place at a hospital in Mississippi (Dent, 1949) where hospitals were segregated into the 1960’s. And to this day, women of color in the United States are less likely to have access to prenatal care and face a higher likelihood of dying giving birth.

This blatantly racist research is the kind of thing the majority of academics would like to see consigned to history but because our attitudes about women’s ability to give birth haven’t changed since the 1940’s, Schultz’s paper is still championed and OD is still promoted as fact.

“The Obstetrical Dilemma hypothesis denotes the evolutionary trade-off(s) between neonate body and brain size, developmental state in terms of altriciality, and maternal pelvic size and shape constraints. As demonstrated by A.H. Schultz […] Schultz’s pioneering research inspired a suite of studies analyzing how neonatal-maternal dimensions and obstetric constraints are related to body size, sexual dimorphism, locomotion, litter size, and life history parameters.” Ponce de Leon and Zollikofer, 2016.

But it wasn’t until Washburn’s 1960 article in Scientific American that the Obstetrical Dilemma was punted into a popular consciousness and is often credited as the first on the subject. Washburn was a contemporary of Schultz, and his work is cited frequently by Schultz. The article is generally about how tool use by pre-human ancestors shaped modern humans– certainly a theory I support. However, the article was very much of it’s time and understanding of human evolution. For example, he describes a “man-ape” similar to modern gorillas and even monkeys as a kind of missing link between modern humans and other primates. Today we understand that there is no “missing link”, no “ascent of man” (the cheeky graphic I use for my logo is based on an obsolete theory of human evolution) or “man the hunter”. Towards the end of the article he touches briefly on human birth as a justification for the patriarchy, or the cultural norms of his time, that is, a nuclear family unit with wife as homemaker caring for children and husband as breadwinner.

“The slow-moving mother, carrying the baby, could not hunt, and the combination of the woman’s obligation to care for slow-developing babies and the man’s occupation of hunting imposed a fundamental pattern of the social organization of the human species.” Washburn, 1960, 74.

Grave Consequences

popular science bad at making babies
Popular Science article from June 2018 promoting the myth of the OD.

Though Obstetrical Dilemma has been discredited on all points as early as 1973, the foundations of the theory, racism, thinly veiled misogyny and a disdain for the physical dependency of infants has remained (or grown) in western culture and has been spread around the world in the preceding decades. The hypothesis has been used to justify both the lack of access to health care (women of color and/or indigenous women) as well as unnecessary and often dangerous interventions during birth and to make women afraid of their supposedly flawed bodies.

“Human beings should not exist. Our skulls are so large that we risk being stuck and dying even as we are struggling to be born. Helped out by a technical team– obstetricians, midwife, and a battery of bleeping machines– the unwieldy cranium is followed into the light by a pathetic excuse for a mammalian body, screaming, hairless, and so muscularly feeble that it has no chance of supporting its head properly for months.” Taylor, The Artifical Ape, 4.

The logic goes that if a woman’s pelvis is the problem during birth, just by-pass it with a surgical birth. The resulting rise in c-section rates has led to a rise in maternal mortality. Obstetrical Dilemma isn’t just scientifically inaccurate– it’s killing women, healthy women are three times as likely to die from c-section than vaginal birth (Mascarelle, 2017). While c-sections can be life-saving for both mother and baby beyond fetopelvic proportions, they are contraindicated for “big babies” based on ultrasound estimates of fetal size, which has “significant error levels” (Milner, 2018) and have put millions at risk for surgical complications and risks in future pregnancies. The WHO recommends a c-section rate of 10-15%, stating that there is no evidence of a reduction in maternal or infant death beyond 10%. Yet in the United States, the average rate (from hospitals that report their stats) is 31.9% according to the the CDC. But OD has an impact on the lives of parents far beyond surviving birth, it colors cultural perceptions of women and infants by insisting that something is terribly wrong with our newborns and it’s the mother’s fault.

While Taylor’s imagining our earliest human ancestors laboring somewhere in the African savannah with a technical team and bleeping machines, real women to this day are giving birth in all kind of environments, very often at home many or most without an obstetrician to newborns with extraordinary abilities, including lifting their heads, supporting their body weight with hand grip, crawling to the breast, holding the gaze of humans, recognizing the language of their mothers, stepping reflex, and more. Pathetic indeed. As far as I am concerned, there is nothing wrong with the development of healthy newborns or with the material bodies that grew and gave birth to them.

“In all the apes and monkeys the baby clings to the mother; to be able to do so, the baby must be born with its central nervous system in an advanced state of development. But the brain of the fetus must be small enough so that birth may take place. In man adaptation to the bipedal locomotion decreased the size of the bony birth-canal at the same time that the exigencies of tool use selected for larger brains. This obstetrical dilemma was solved by delivery of the fetus at a much earlier stage of development. But this was possible only because the mother, already bipedal and with hands free of locomotor necessities could hold the helpless, immature infant.” Washburn, 1960, 73-74.

Washburn seems to be under the misconception that maternal pelvises and fetal brains developed independently of each other– that’s not how evolution works– mothers and their offspring co-evolved. In part two, I will show how humans have pelvises perfectly adapted to give birth to human infants. In fact, the human pelvis would only need to be 3-4 cm larger to give birth to an adult-sized skull (Epstien, 1973; Dunsworth, 2012). We also now know that our first bipedal ancestor was at least 4 million years ago and that brain size has gone up as bipedal pelvises have gotten narrower, there is a positive selection pressure for big headed babies born to narrow hipped mothers. Tool use did not make human brains larger, though our species is the latest in an increasingly technology-dependent line.

In part three, I cover the developmental side of the OD, namely this idea that our infants are born prematurely compared to other primates. There are many theories, including social development, maternal metabolism, and oxygen for brain growth to explain when human infants are born. Dunsworth’s research shows that when compared to non-human apes, humans gestate longer and give birth to bigger neonates that is expected for our size. Yet, in order for a human neonate to match the physical development of a chimpanzee neonate, humans would need to gestate for around 19 months (Portman, 1990)—even if that were physically possible, consider all the worldly experiences the infant would miss out on while in the womb. Imagine first meeting your child when they are 19 months of age.

We now understand that there is a lot more going on with apes and monkeys when it comes to clinging. For example, not all primates “ride”, some “park” their infants (Ross, 2001). For those that do cling, the infants need four functional, grasping limbs and the mother (or allomother) needs to have a specific density and length of body hair to support the grasping infant (Amaral, 2008). And even non-bipedal primates we have seen carrying adaptations in modern primate mothers when an infant is disabled or even dead. In part four I go into greater detail on how the invention of the infant carrier helped our bipedal ancestors carry poorly clinging infants allowing Washburn’s “slow-moving mothers” to pick up the pace, escape predation, forage, hunt, and participate in the life of her social group without having to use her freed up hands to hold the infant.

Scientists like Schultz and Washburn were products of their time when racism and sexism were considered scientifically supported and they make up the foundations of the Obstetrical Dilemma. In the face of forty-five years of data refuting the hypothesis, how can modern researchers –those who reject racism, consider themselves feminists, and base their work on the scientific method– promote the Obstetrical Dilemma? This is a medical myth that justifies the unnecessary cutting of women’s bodies, via episiotomy or cesarean and has increased women’s suffering and maternal mortality for generations– it needs to die, its proponents publically (and privately) shamed.

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Amaral, Lia Q. 2008. “Mechanical Analysis of Infant Carrying in Hominoids.” Naturwissenschaften 95:4, 281-92.

Dent, Albert W. 1949. “Hospital Services and Facilities Available to Negroes in the United States.” The Journal of Negro Education: The Health Status and Health Education of Negroes in the United States 18:3, 326-332

DeSilva, Jeremy M. 2011. “A shift towards birthing relatively large infants early in human evolution.” PNAS 108:3, 1022-1027.

Dunsworth, Holly M., Anna G. Warrener, Terrence Deacon, Peter T. Ellison, and Herman Pontzer. 2012. “Metabolic hypothesis for human altriciality.”
PNAS 109:38, 15212-15216; DOI:10.1073/pnas.1205282109

Epstein, Herman T. 1973. “Possible metabolic constraints on human brain weight at birth.” The American Journal of Physical Anthropology 39:1, 135-136. https://doi.org/10.1002/ajpa.1330390114

Mascarello KC, Horta BL, Silveira MF. 2017. “Maternal complications and cesarean section without indication: systematic review and meta-analysis.” Revista de Saúde Pública. 51:105. doi:10.11606/S1518-8787.2017051000389.

Milner, J and J Arezina. 2018. “The accuracy of ultrasound estimation of fetal weight in comparison to birth weight: A systematic review.” Ultrasound 26:1, 32-41. doi: 10.1177/1742271X17732807.

Portman, Adolf. 1990. A Zoologist Looks at Humankind. Translated by Judith Schaefer. Chicago: Columbia University Press.

Ross, Caroline. 2001. “Park or Ride? Evolution of Infant Carrying in Primates.” International Journal of Primatology 22:5, 749-71. Springer.

Taylor, Timothy. 2010. The Artificial Ape: How Technology Changed the Course of Human Evolution. New York: Palgrave Macmillian.

Wall-Scheffler, et al. 2007. “Infant Carrying: the role of increased locomotory costs in early tool development.” American Journal of Physical Anthropology 133: 841-846.

Warrener, Anna, Kristi L. Lewton, Herman Pontzer, and Daniel E, Liberman. 2015. “A Wider Pelvis Does Not Increase Locomotor Cost in Humans, with Implications for the Evolution of Childbirth.” PLOS One 10:3, e0118903.

Washburn, Sherwood L. 1960. “Tools and Human Evolution.” Scientific American 203:3, 63-75.

6 thoughts on “Squished Part 1: What is the Obstetrical Dilemma?

  1. Greetings from Türkiye.
    As one of the first baby wearing consultants (trained by ClauWi), I was also tought this “dilemma”. As an activist feminist and an certified biolog, I’m so happy to read your article. And I also really want to translate it to Türkçe, and have it on my baby wearing & livability blog – which tries to with the e-shop ( http://www.kuzo.com.tr ).
    May I translate and of course share it with full credits???

    Thank you anyway, it’s so wonderfull what you do her on ” http://www.evolutionofbabywearing.com ” 🙂

    My best,


  2. Greetings from Türkiye.
    As one of the Türkiye’s first baby wearing consultants (trained by ClauWi), I was also tought this “dilemma”. As an activist feminist and an certified biolog, I’m so happy to read your article. And I also really want to translate it to Türkçe, and have it on my baby wearing & livability blog – which tries to change the world more and more rapidly with combination of its e-shop ( both are availible on http://www.kuzo.com.tr ).
    May I translate and of course share it with full credits???

    Thank you anyway, it’s so wonderfull what you do her on ” http://www.evolutionofbabywearing.com


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