Fetal-Pelvic Disproportion and Pelvic Asymmetry As a Potential Cause for High Maternal Mortality in Archaeological Populations
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FETAL-PELVIC DISPROPORTION AND PELVIC ASYMMETRY AS A POTENTIAL CAUSE FOR HIGH MATERNAL MORTALITY IN ARCHAEOLOGICAL POPULATIONS by SARAH STANSFIELD B.A. University of Missouri, 2011 A thesis submitted in partial fulfillment of the requirements for the degree of Master of Arts in the Department of Anthropology in the College of Sciences at the University of Central Florida Orlando, Florida Summer Term 2013 © 2013 Sarah Stansfield ii ABSTRACT Females of childbearing age are overrepresented in the population of the Kellis 2 cemetery (100-450 AD) in the Dakhleh Oasis, Egypt (Wheeler 2009). The demographic overrepresentation found here may be the result of complications related to childbirth. Clinical literature demonstrates that fetal size is rarely an explanation for failed labor (Cunningham et al. 2001) and the fetuses buried in the Kellis 2 Cemetery at the Dakhleh Oasis were not larger than average (Tocheri et al. 2005), directing the focus to dimensions of the maternal pelvis for evidence of obstetrical issues, such as abnormally compressed pelvises. To formulate a test for this hypothesis, a total of 50 adults, 24 of which are female, were examined for this study. The sample consisted of individuals from an archaeological population from the Dakhleh Oasis, Egypt as well as from six populations housed in the American Museum of Natural History (NYC). These include archaeological populations from the sites of El Hesa and Sai Island in the Sudan, also South Africa, Nubia, and India, as well as a medical collection from North America. Pelvic dimension and asymmetry was determined through nine measurements of the pelvis and sacrum. Kruskal-Wallis tests were used to analyze variance and assess whether the younger females in this group may have been at a higher risk of death during childbirth due to fetal-pelvic disproportion. Mann-Whitney-Wilcoxan nonparametric tests were used to assess differences in asymmetry in young and old groups. A MANOVA test assessed overall variation in the population. Results indicate significant differences between young and old females in pelvic outlet anteroposterior diameter, a measure of midpelvic contraction, as young females had smaller pelvic outlet anteroposterior diameters. There were also significant differences between iii young and old females in alar-pubis length asymmetry; the young females were more asymmetric. These differences were not found in the male groups. It is suggested that these differences could impact childbirth as a contracted midpelvis, such as that found in the young female group, can cause transverse arrest of the fetal head (Cunningham et al. 2010) and pelvic asymmetry can contribute to obstetrical complications (Campbell et al. 2011). iv ACKNOWLEDGMENTS I first want to thank my excellent advisor, Tosha Dupras, for her guidance and encouragement as I worked on my thesis. Without her help I would not have been able to complete this thesis. I want to thank Edgard Maboudou for his help with the statistical analysis. Dr. Maboudou was always patient as I slowly learned all the necessary procedures in R and in my statistics books. Sandra Wheeler also played a large role in making my thesis better, her constructive criticism made this manuscript much clearer and better organized. I also want to thank Gisselle Garcia and Jacklyn Lacey for granting me access to the collections at the American Museum of Natural History and for all their help in finding specific collections. The Dakhleh Oasis Project and its members helped a lot in forming the hypothesis I decided to investigate and made for a wonderful experience with Egyptian archaeology. Dr. Dupras, Dr. Wheeler, Dr. Lana Williams, Dr. Peter Sheldrick, Amanda Groff, Paul Kucera, Dr. Christine Lee, Jennifer Branson, and Brittany Walter all made the trip both incredibly fun and very rewarding. A large number of my fellow graduate students provided encouragement and support throughout the writing of this thesis. I want to especially thank Cayli Meizel-Lambert, Brittany Walter, Jennifer Branson, and MacKenzie See for their support academically and their reminders to relax and have fun occasionally as well. A big thank you to my roommate, Kim Zipoli, for making me a little bit scared to come home from the library without significant thesis progress to report. You’re going to be a fantastic teacher, I can’t imagine having to tell you I didn’t do my homework. I want to thank Campbell Massie, Patrick Kopp, Ted Floros, and Jessica Elliot for v their encouragement whenever I needed it. I also want to thank my entire family for their encouragement along the way, no matter how many times I had to explain what exactly I was investigating. vi TABLE OF CONTENTS LIST OF FIGURES ..................................................................................................................... viii LIST OF TABLES ......................................................................................................................... ix CHAPTER 1: INTRODUCTION ................................................................................................... 1 CHAPTER 2: LITERATURE REVIEW ........................................................................................ 3 Mechanics of Childbirth ........................................................................................................................... 3 Age Related Issues in Labor ..................................................................................................................... 6 Pelvic Morphology ................................................................................................................................... 9 Normal Pelvises ...................................................................................................................... 9 Compressed Pelvises ............................................................................................................. 13 Asymmetric Pelvises ............................................................................................................. 15 Fetal-pelvic disproportion ....................................................................................................................... 17 Modern .................................................................................................................................. 17 Historical ............................................................................................................................... 18 General obstetric problems ..................................................................................................................... 20 Modern .................................................................................................................................. 20 Historical ............................................................................................................................... 22 CHAPTER 3: MATERIALS AND METHODS .......................................................................... 25 Materials ................................................................................................................................................. 25 Measurement .......................................................................................................................................... 29 Analysis .................................................................................................................................................. 38 Sex Differences ..................................................................................................................... 40 Size Differences .................................................................................................................... 40 Symmetry Differences .......................................................................................................... 40 CHAPTER 4: RESULTS .............................................................................................................. 42 Differences in Sex .................................................................................................................................. 43 Differences in Size.................................................................................................................................. 43 Differences in Symmetry ........................................................................................................................ 46 Differences in Shape ............................................................................................................................... 47 CHAPTER 5: DISCUSSION ........................................................................................................ 49 Sex Differences....................................................................................................................................... 49 Pelvic Contraction .................................................................................................................................. 50 Pelvic Asymmetry .................................................................................................................................. 53 Pelvic Shape ........................................................................................................................................... 55 Limitations .............................................................................................................................................. 56