Graduation Year


Document Type




Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department


Major Professor

Lorena Madrigal, Ph.D.

Committee Member

David A. Himmelgreen, Ph.D.

Committee Member

Elizabeth M. Miller, Ph.D.

Committee Member

Linda A. Detman, Ph.D.

Committee Member

Wenda R. Trevathan, Ph.D.


Cortisol, Evolutionary Medicine, Homebirth, Obligate Midwifery, Physiological Normal Birth


This dissertation is based on evolutionary medicine and applied anthropological research where the narratives and biology of modern women are used to inform evolutionary theory, specifically obligate midwifery, and modern birth practices. Improvements to the US maternity care systems are needed as rates of maternal mortality and morbidity are continually higher than rates in other technologically advanced nations. Additionally, women birthing under the technocratic model of care, as is predominant in the US, report trauma and post-traumatic stress disorders due to their birthing experience, and more women are experiencing postpartum depression. Thus, I seek to use an evolutionary medicine perspective and applied anthropological research methods to inform modern birthways and specifically how to realize physiological normal birth in more instances.

I conducted research that unfolded incrementally in a three-phased approach. In study section A, 226 participants responded to an online survey. These responses were used to establish six themes regarding 'what women want' in their birth experience and ultimately what environment is conducive to physiologic normal birth.

In study section B, four women collected five saliva samples each using dental swabs during their peripartum period, from early labor through 12 hours postpartum. These saliva samples were used to establish, first, that saliva collection for cortisol research among homebirth mothers is a viable research method, and second, to document, for the first time known to me, the cortisol profile of homebirth mothers who experience a physiological normal birth.

Study Section C expanded on the knowledge gained from sections A and B. In this section, six women were recruited, and four completed all segments of the study section, which included saliva samples, face-to-face interviews, and standardized questionnaires. The saliva sample protocol included the same five saliva samples collected in section B and expanded the protocol by requesting 16 additional saliva samples in the prenatal period to establish a cortisol baseline before labor was initiated.

I found that when listening to women, their desires for birth can be described using six themes: 1) Be Respected; 2) Find Empowerment; 3) Create Atmosphere; 4) Have Autonomy; 5) Follow Instincts; and 6) Keep Baby Close. I found that when women described what they wanted and what environment was conducive to a physiological normal birth, their narratives included the presence of a knowledgeable and caring assistant. Through the use of the standardized questionnaires, I found that women who were seen prenatally by a homebirth midwife had low levels of anxiety and low levels of fear of childbirth. And lastly, through analysis of the cortisol levels of eight physiologically normal homebirths, I found that cortisol levels begin to rise as early as when the mother perceives she is in early labor and spike at the moment of birth, perhaps higher than in any other human experience.

Thus, I conclude that birth is a time of great emotional vulnerability due, in part, to the extreme rise in cortisol levels and that a knowledgeable and caring assistant can mitigate that vulnerability by attending to the mother prenatally and perinatally. These findings lend weight to the obligate midwifery hypothesis in that assistance at birth is part of our evolutionary biological history, and assistance at birth is conducive to physiological normal birth when the birth attendant acknowledges the woman's birth desires.