What to Expect when Mice Are Expecting: Pregnancy-Driven Changes in the Reproductive Tract

Pregnancy and childbirth, while natural processes, still present significant complications that affect the mother and baby in the short and long term such as pre-term birth, vaginal tearing, and pelvic organ prolapse. The female reproductive tract undergoes dramatic changes during pregnancy and postpartum recovery, requiring coordinated efforts across the vagina, cervix, and uterus. From an engineering perspective, we still do not know how much or why these forces change the organs' ability to stretch over time, and why some people experience complications. Scientists are unlikely to test on humans during pregnancy, so they use animal models, such as the mouse, which are commonly used in basic science research for humans. This project uses a mouse model through three studies to describe the changes in the female reproductive tract during pregnancy and postpartum. First, magnetic resonance imaging was used to measure the shape and size of the reproductive tract for the same mouse over pregnancy and up to three weeks after delivery. The uterus grew up to 49 times its original virgin size at late pregnancy before returning to near-virgin size three weeks after delivery. The cervix had shape changes similar to those seen in humans at late pregnancy while the vagina, showed permanent changes in shape near the cervix. The second study pressurized the reproductive tracts of mice outside of the body to describe how the different organs stretched as a unit. The reproductive tracts were more flexible at late pregnancy and postpartum than the virgin ones, and less pressure was needed to break them at later time points. While uterine and vaginal tissue stretched similarly at low pressures, the uterus demonstrated greater stretch at high pressures. Finally, a unique imaging technique, second harmonic generation microscopy, was used to look at the collagen (i.e., fibers inside the tissue that allow it to stretch) in the vagina, cervix, and uterus over pregnancy and postpartum recovery. Fibers in the vagina were curlier than the fibers seen in the cervix and uterus. During pregnancy, fibers became more aligned. After delivery, there were more fibers within the vagina, cervix, and part of the uterus. The information found in this project is important because it provides baseline data for healthy mouse pregnancies that can ultimately contribute to understanding pregnancy- and birth-related complications and developing future prevention strategies.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Biomedical Engineering

Department dc:contributor.department

Department of Biomedical Engineering and Mechanics

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2025

Author dc:creator

• Suarez, Aileen Caridad

Chair dc:contributor.committeechair

• De Vita, Raffaella

Committee members dc:contributor.committeemember

• Staples, Anne E.
• Munson, Jennifer M.
• Miller, Kristin
• Collins, Caitlyn Jayne

• biomechanics
• collagen
• pregnancy remodeling

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

vt_gsexam:43159

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/135058