Hormone trajectories leading to human birth

Area of Science:

• Reproductive biology
• Maternal-fetal medicine
• Endocrinology

Background:

• Human parturition mechanisms remain largely unknown, contributing to high rates of neonatal mortality and cerebral palsy from preterm birth.
• Current preterm birth prediction and treatment methods lack efficacy due to limited understanding of underlying biological processes.
• Parturition is increasingly viewed as a complex cascade involving maternal, fetal, and placental factors throughout pregnancy.

Purpose of the Study:

• To investigate the role of progesterone receptor isoforms in initiating human parturition.
• To test the hypothesis that increased progesterone receptor A (PR-A) concentrations trigger the onset of labor.

Main Methods:

• Analysis of progesterone receptor A (PR-A) and progesterone receptor B (PR-B) actions in the human myometrium.
• Investigating the proposed role of placental Corticotropin-releasing hormone (CRH) in the parturition cascade.
• Examining the balance of progesterone withdrawal and estrogen activation in human labor.

Main Results:

• Two progesterone receptor forms, PR-A and PR-B, exhibit opposing functions in the myometrium.
• PR-A acts as a dominant-negative repressor of PR-B activity.
• Preliminary data suggest elevated PR-A levels initiate human parturition.

Conclusions:

• The shift in progesterone receptor balance, specifically the rise of PR-A, is a key event in initiating human labor.
• Understanding PR-A's role provides a potential mechanism for predicting and treating preterm birth.
• Further research into CRH and progesterone signaling is essential for advancing reproductive medicine.