History of Reproduction 3

The Emergence of Midwifery as a Necessary Consequence of Bipedalism

Welcome to the blog post about the history of midwifery! It’s great to have you here.

 

Are you interested in human evolution and its consequences for human reproduction? That’s great! Then this article is just right for you.

 

In the following, you will learn how the female human body has evolved over the last millennia and what effects this has had on one of the most crucial processes of reproduction, namely delivery. Specifically, you will learn how a key physiological change in human evolution, bipedalism, significantly complicated the process of giving birth and why this led to the emergence of the midwifery profession as it is commonly practised today.

 

We, Lisa, Ninke, Sarah & Jasper, wish you an interesting and entertaining time reading this blog post! We hope that you can take something from it and move on with more knowledge and insight into the history of midwifery.

Table of Contents

Midwifery and its Origins

Midwives can be found in all human societies and play an important role before, during, and after human childbirth. The tradition of assisting the birthing mother does not only facilitate the birth, but contributes significantly to the safety of both the mother and her baby and the success of the delivery. According to DeSilva et al. (2017), the complex nature of human birth created the need for assistance, as the mother and her child have to complete a complicated and dangerous process to survive the delivery. 

When primates started walking on two legs instead of four, their skeletal morphology changed dramatically, creating narrower hips and thus a smaller birthing canal. Additionally, the brain, head and shoulder width of fetuses has increased in size (Rosenberg, 1992). The resulting problems were more complicated birthing procedures, involving higher risks for both the mother and her child. 

The complications arising in human childbirth today can be traced back to the Australopithecus afarensis, who seemed to struggle especially with the size of the child’s shoulders compared to the size of the mother’s pelvis during childbirth (DeSilva et al., 2017). The Australopithecus afarensis is one of the earliest human ancestors with “Lucy” as its famous representative (Choi, 2017). Lucy, who has lived between 2.9 and 3.8 million years ago, probably would have had similar problems with childbirth as contemporary women; however, primarily because of the baby’s shoulder size instead of its head or brain size as most prominent today (Choi, 2017). Hence, the need for assistance during childbirth emerged around three million years ago and has since become a natural component of human reproduction.

 

Notes: Australopithecus afarensis (Fineartamerica, 2013).

Furthermore, the findings of contemporary studies suggest that since Lucy, human communities became increasingly social as they were caring for each other’s well-being and helped one another when necessary (Rosenberg, 1992). For example, Russell (1982) traces birthing practices throughout different centuries and cultures, discovering early accounts of midwifery in Indo-China, Greece, and North America. According to the author, already more than one hundred years ago scientists discovered that the size of the birth canal increases if the woman delivers her child in a vertical position (Russell, 1982). Early evidence for special birthing practices and the assistance through birth helpers can be found in prehistoric and Egyptian writings, as well as the Old Testament (Drife, 2002). Hence, we can observe that midwifery care is not a new phenomenon. In fact, assisted reproduction has slowly developed and persisted over several millennia.

The Obstetrical Dilemma

Now that you know something about the history of midwifery care, let us have a look at one of the key evolutionary developments that has made the emergence of assisted reproduction a necessity.

Bipedalism is a defining feature of humans. Even as bipedalism is not unique to the human race, the form used by humans cannot be found in other species. The main difference is that humans can really walk upright, whereas other bipeds only hop or waddle (Tuttle, 2020). The Homo sapiens are the only mammals that adapted in such a way that exclusively uses bipedalism for walking (Tuttle, 2020). The changes in anatomy needed to allow bipedalism mainly focus around the differences in joint and ligament construction in comparison to the other primates (Tuttle, 2020). Especially the pelvis underwent a drastic change to accommodate bipedalism (Gruss, 2015).

 

 

Notes: Differences between human and gorilla pelvis. It shows the consequences of bipedalism on the width and structure of the human pelvic inlet (Napier, 2010).

These different joint formation and alignment can be seen on fossils found from these human-like species. Analysis of fossils found from various hominid species, seems to suggest that bipedal walking already started developing six million years ago (Tuttle, 2020). The oldest footprints found indicating contemporary foot function and exclusive bipedal walking, have been dated to be approximately 1.51 to 1.53 million years old (Tuttle, 2020).

However, the pelvis has another important function. Especially in relation to evolution and selection. The pelvic shape is crucial for the delivery of a healthy child during childbirth without causing harm to the mother (Rosenberg, 1995). The changes needed for the development of bipedalism, resulted in a reduction of the width of the pelvic outlet, making childbirth a more laborious process.

Next to this, a steep increase in the size of the human brain has been found starting from the Homo habilis to the Homo sapiens sapiens (Van Ginneken, 2017). How did this increase in the human brain occur? 

 

Notes: Human evolution based on skull endocasts of fossil archaic primates and early hominids. It shows the gradual increase in human brain size; which is especially prominent from the Australopithecus Africanus (Van Ginniken, 2017).

It is known that the placenta is very important for the development of the fetus during pregnancy. It delivers oxygen and nutrients to the growing baby and therefore the effectiveness of the placenta largely determines the size of the fetus. An effective placenta needs slow blood flow and not much pressure behind the blood flow to increase the possibility of successful transport of nutrients across the placental membranes (Moffet, 2015). This is ensured by certain cells from the placenta, called the trophoblasts deeply invading the arteries, which in turn leads to a decreased ability of these arteries to become smaller in diameter (Hill, 2020). Arteries with larger diameters mean a slower and less pressured flow of blood. This deep invasion of these trophoblasts can only be found in humans; all other primates have a more superficial invasion (Carter, 2011). Due to this, the fetal size remains more limited, allowing easier passage through the birthing canal of the mother. 

 

Notes: The right panel shows the remodeling of the arteries needed for a slow and low pressure blood flow. Good blood flow determines for a large part the size of the fetus (Moffett, 2015).

Another problem associated with the deeper invasion seen in humans is that the placental ‘non-mother’ trophoblasts have more interaction with the cells from the mother (Moffet, 2015). Normally ‘non-self’ cells will be attacked by the immune system. However, this is not observed in pregnancy (Moffet, 2015). This is because the trophoblasts have different proteins on their surface, making it more difficult for the mother’s immune system to recognize these cells as ‘non-self’ (Apps, 2009). The mother’s cells responsible for clearing ‘non-self’ cells, the natural killer cells, have receptors to recognize the proteins on the surface of cells. This receptor can attach to a protein and signal either a destructive or activating signal (Moffet, 2015). The proteins on the trophoblast cells mainly give a stimulating effect. Due to this, other signals and molecules are released enhancing growth of the fetus (Xiong, 2013). This contributes to the increased fetal size seen in humans compared to primates. 

 

Notes: The interaction between the immune system of the mother and the placental trophoblasts are visualized. Also, the link between this interaction and the birthweight of the child are depicted (Moffett, 2015).

Both traits, the increase of the fetal head and bipedalism, have evolved for several million years, it can be assumed that there is a selective pressure in favor of these traits (Tuttle, 2020). Due to the increased brain size and the decreased width of the maternal pelvis, humans have been more prone to have obstetric complications, such as obstructive labor. This increased tendency to having problems during delivery and pregnancy has contributed to the development of midwifery care and assisted reproduction.

Discussion

In most European countries, amongst others the Netherlands, obstetric care is divided into primary and secondary care (Heres, 2000). The level of care  that will be administered to a pregnancy depends on whether or not the pregnancy is considered to be of a low or high-risk. Women with a low-risk pregnancy are attended to by midwives and practitioners, thereby falling within the primary care division (Tre􏰀ers, Eskes, Kleiverda, 1990). High-risk pregnancies where medical complications are more likely to arise, either before or during labour, are taken over and monitored by secondary care, namely obstetricians. A study comparing the spontaneous labour of women cared for by an obstetrician and women cared for by a midwife has shown that women under the care of an obstetrician had a delayed time of birth (Heres, 2000). While confirming the need for an assisted birth as a result of the evolution of the pelvic canal, this study also highlights the essential input a midwife can have in a healthy delivery.


(Tolkinnen, 2019)

Labour can be affected by a number of factors that include physical features of the fetus such as its considerably larger head, the pelvic canal of the mother that has evolved due to bipedalism, but also other factors such as environmental disturbances, fright and perceived dangers (Yerushalmy, 1938). The physical presence of a companion during labour and the constant human support significantly reduces the length of labour (Klaus, Kennell, Robertson,1986, Flint, Poulengeris, Grant, 1989). The presence of a midwife not only guarantees constant human support, but also creates a safe and trustworthy environment for the birthing mother as a result of the midwife’s expertise and experience in obstetric care. The crucial role of a birth helper, although the means through which they help have changed in the course of history,  has been documented over centuries (Brussel, 1982). Overall, it can be established that the role of midwives has positively impacted the highly complicated process of giving birth by providing the necessary support and guidance to the birthing mother.

Picture: “A position to accelerate labour from Indo China, illustrating the vertical pole, seen in many civilizations, and also the helper on her shoulders. This effectively increases the mother’s weight and thus forces acting on the pelvis” (Brussel, 1982).

Congratulations! You successfully finished the blog post about the routes of midwifery and its biological origins. We hope that you could learn something and wish you an exciting day checking out the other Ateliers of this year’s online Petrus Camper Festival.

 

All the best & stay safe,

Lisa, Ninke, Sarah & Jasper.

 

References

  • Apps, R., Murphy, S. P., Fernando, R., Gardner, L., Ahad, T., & Moffett, A. (2009). Human leukocyte antigen (HLA) expression of primary trophoblast cells and placental cell lines, determined using single antigen beads to characterize allotype specificities of anti‐HLA antibodies. Immunology, 127(1): 26-39.
  • Carter, A. M., & Pijnenborg, R. (2011). Evolution of invasive placentation with special reference to non-human primates. Best Practice & Research Clinical Obstetrics & Gynaecology, 25(3): 249-257.
  • Choi, C., Q. (2017). Did Human Ancestor “Lucy” Have a midwife?. Retrieved from: https://www.livescience.com/58844-did-human-ancestor-lucy-have-midwife.html (Accessed 26 May 2020).
  • DeSilva, J. M., Laudicina, N. M., Rosenberg, K. R., & Trevathan, W. R. (2017). Neonatal shoulder width suggests a semirotational, oblique birth mechanism in Australopithecus afarensis. The Anatomical Record, 300(5): 890-899.
  • Drife J. (2002). The Start of Life: A History of Obstetrics. Postgraduate Medical Journal, 78 (919): 311–15.
  • Fineartamerica. (2013). Australopithecus Afarensis, Artwork. Retrieved from: https://fineartamerica.com/featured/australopithecus-afarensis-artwork-mauricio-anton.html (Accessed 15 June 2020).
  • Flint, C., Poulengeris, P., & Grant, A. (1989). The ‘know your midwife’ scheme – a randomised trial of continuity of care by a team of midwives. Midwifery, 5(1): 11-16.
  • Gruss, L. T., & Schmitt, D. (2015). The evolution of the human pelvis: changing adaptations to bipedalism, obstetrics and thermoregulation. Philosophical Transactions of the Royal Society B: Biological Sciences, 370(1663): 20140063.
  • Heres, H. B., Maria, P., Marion, B., Pieter, E. T., & Majid, M. (2000). The hour of birth: comparisons of circadian patterns between women cared for by midwives and obstetricians. Science Direct, 16(3): 173-176.
  • Hill, M. A. (2020). Embryology Trophoblast. Embryology. Retrieved from: https://embryology.med.unsw.edu.au/embryology/index.php/Trophoblast (Accessed 3 June 2020).
  • Klaus, M. H., Kennell, J. H., Robertson, S. S., & Sosa, R. (1986). Effects of social support during parturition on maternal and infant morbidity. British Medical Journal, 293(6547): 585-587.
  • Moffett, A., Hiby, S. E., & Sharkey, A.M. (2015). The role of the maternal immune system in the regulation of human birthweight. Philosophical Transactions of the Royal Society B: Biological Sciences, 370(1663): 20140071.
  • Napier, J. R. (2019). Bipedalism. Encyclopaedia Britannica. Retrieved from: https://www.brittanica.com/science/bipedalism (Accessed 15 June 2020).
  • Rosenberg, K. R. (1992). The Evolution of Modern Human Childbirth. American Journal of Physical Anthropology, 35(S15): 89-124.
  • Rosenberg, K., & Trevathan, W. (1995). Bipedalism and human birth: The obstetrical dilemma revisited. Evolutionary Anthropology: Issues, News, and Reviews, 4(5): 161-168.
  • Russell, J. G. B. (1982). The Rationale of Primitive Delivery Positions. Bjog: An International Journal of Obstetrics & Gynaecology, 89(9): 712-15.
  • Treffers, P. E., Eskes, M., Kleiverda, G., & Van Alten, D. (1990). Home births and minimal medical interventions. Journal of the American Medical Association, 264(17): 2203-2208.
  • Tolkinnen, K. (2019). Country’s first midwife tells her story. Echo Press. Retrieved from: https://www.echopress.com/lifestyle/health/4724953-Countys-first-midwife-tells-her-story (Accessed 15 June 2020).
  • Tuttle, R. H. (2020). Human evolution. Encyclopaedia Britannica. Retrieved from: https://www.britannica.com/science/human-evolution (Accessed 28 May 2020).
  • Van Ginneken, V., van Meerveld, A., Wijgerde, T., Verheij, E., de Vries, E., & van der Greef, J. (2017). Hunter-prey correlation between migration routes of African buffaloes and early hominids: Evidence for the “Out of Africa” hypothesis. Integr Mol Med, 4(3): 1-5.
  • Xiong, S., Sharkey, A. M., Kennedy, P. R., Gardner, L., Farrell, L. E., Chazara, O., & Moffett, A. (2013). Maternal uterine NK cell–activating receptor KIR2DS1 enhances placentation. The Journal of clinical investigation, 123(10): 4264-4272.
  • Yerushalmy, J. (1938). Hour of birth and stillbirth and neonatal mortality rates. Child Development, 9: 373-378