Bipedalism and Parturition: An Evolutionary Imperative for Cesarean Delivery? Stuart Weiner MD, Janet Monge PhD, Alan Mann PhD. Clinics in Perinatology 35(3): 469-478 2008
Published nearly four years ago, this paper reflects the extraordinary level of support and credence anthropology has given to the medical system to perform invasive and unnecessary obstetrical interventions. Anthropologic theory, as described by Abitbol, Trevathan, Rosenberg and others, regards human birth as an “obstetrical dilemma” that is dangerous for both mother and child, and must therefore be “eased” by obstetric intervention.
The authors of this study state that pelvic morphology evolved primarily to meet the needs of bipedal posture. The pelvis resulting from human evolution is said to be of inadequate size and shape for safe parturition, even though these changes were wrought through the processes of natural selection. “In the end, this parcel of evolutionary features results in a birth process that is, without medical intervention, painful and dangerous for mothers and their young.”
They cite obstetrician and anthropologist, Maurice Abitbol, who estimated that approximately 20% to 25% of human births throughout the course of evolutionary time ended in maternal or fetal death. Death from what? The inference is that occiput-pelvic disproportion has resulted in huge loss of maternal and fetal life throughout the ages. However, this assumption is not reflected in current World Health Organization statistics for developing nations where birth remains largely natural. Maternal mortality from all causes in developing countries is 2.9 per 1,000 births, while average death rates of newborns is 33 per 1,000 live births. The main causes of newborn mortality are prematurity and low-birth-weight, infections, and asphyxia (lack of oxygen at birth).
Abitbol has been the most widely-published promoter of the obstetrical dilemma, influencing two generations of obstetricians who have been largely responsible for the soaring cesarean rates in many parts of the world. In light of what we now know about the true orientation of the human pelvis and the dynamics of pelvic organ support, Abitbol’s words fly in the face of logic and reason:
“First, the abdominal cavity is already, relatively speaking, smaller in a superior-inferior direction in view of the sacralization of the last two lumbar vertebra (L6 and L7) and their integration into the sacrum, and smaller in an anterior-posterior direction in view of the formation of the lumbar lordosis. Human pregnancy barely has adequate space in the abdominal cavity, and this results in compression on all surrounding organs, such as the major abdominal vessels, anterior abdominal wall, vertebral and pelvic joints, muscles, ligaments, etc. This is contrary to the quadrupedal condition in which the pregnancy rests comfortably over the anterior abdominal wall with the necessary space available and with no undue pressure on any organ.
Second, the human fetus grows in a ventral direction and, at or near term, the center of gravity of the human body no longer falls over the base of support formed by the feet. To regain her equilibrium, the pregnant woman at term has to lean backwards, and this results in important orthostatic and orthodynamic consequences. Spinal curvatures are completely disorganized. The lumbar curvature moves dorsally and may or may not be accentuated, the thoracic curvature has to compensate accordingly, and the equilibrium of the body has to be maintained in an unusual (painful) position. Because of the dorsal displacement of the trunk, the rectus abdominis muscles have to increase their tension and the intra-abdominal pressure is increased, producing elevation of the diaphragm. The cardiopulmonary consequences are numerous.
Third, from the orthodynamic point of view, the situation is even worse. Because of the backward position of the trunk in relation to the pelvic girdle, the glutei lose some of their abductor function and the pregnant patient at term now wobbles, as previously described. The elegant striding walk, the pride of human erect behavior, is all but gone in advanced pregnancy.” 1
These authors continue in the tradition of Abitbol:
“The fossil record of human evolution suggests that vaginal birth is indeed dangerous for women of childbearing age and their offspring. Encephalization can be documented using the fossil record and it is clear that over the last 2 million years this process has come at a dramatic cost to our species when viewed in concert with the evidence of the early development in our lineage of obligate bipedal movement…Human populations have been dealing with the obstetric dilemma for many hundreds of thousands of years and modern biomedicine, using techniques like cesarean section, has alleviated, but not eliminated, birthing as a ‘scar’ of human evolution.”
Humans are extraordinary creatures in many ways. Human birth is remarkable and sometimes dramatic, as is the fact that babies are born with only 25% of their brain developed and remain totally helpless for more than a year.
The level of negativity anthropology and orthopedics exhibits toward human birth is unwarranted and unsubstantiated by the fossil record. Never is it considered that the female pelvis and fetus are actually a perfect fit. The hormonally-relaxed pelvis widens during birth as the fetal skull collapses in upon itself like a folding vegetable steamer. Many investigators, including Weston Price2 and Kathleen Vaughan3, studied human birth in transitional cultures. They recorded the decline of uncomplicated birth as people moved away from nutritious foods and traditional lifestyles. These important works were eclipsed by the rise of obstetrics, gynecology, and technological birth.
Clearly, much of what is espoused by anthropology and obstetrics is based upon misconception and falsehood. Research that does not take into consideration birth position, the true orientation of the human pelvis, and healthy, natural childbirth should be discarded out of hand.
1 Abitbol M Birth and Human Evolution: Anatomical and Obstetrical Mechanics in Primates. Praeger 1996
2 Price W Nutrition and Physical Degeneration Keats Publishing 1939
3 Vaughan K Safe Childbirth – the three essentials. William Wood & Co. 1937