Study Finds Links Between Preterm Birth And Progesterone Imbalance

Some pregnant women experience preterm labour or prolonged labour due to unbalanced progesterone signals.

A recent study, done on mice and published online in the Proceedings of the National Academy of Sciences, has discovered that some pregnant women experience preterm labour or prolonged labour due to unbalanced progesterone signals.

The study, conducted by the National Institutes of Health, provides novel insights for developing treatments.

The study revealed how  unbalanced PGR-A and PGR-B signaling can affect pregnancy duration. During pregnancy premature labour. This occurs through molecular signaling involving progesterone receptor types A and B, referred to as PGR-A and PGR-B.

“We used genetically engineered mouse models to alter the ratio of PGR-A and PGR-B in the muscle compartment of the uterus, called the myometrium,” said senior author Francesco DeMayo, Ph.D., head of the National Institute of Environmental Health Sciences Reproductive and Developmental Biology Laboratory.

DeMayo added, “Our team found that PGR-A promotes muscle contraction and PGR-B prevents such contraction, and we identified the biological pathways influenced by both forms.”

  • The study assumes significance as preterm birth affects 10 per cent of all pregnancies and is the primary cause of neonatal morbidity and mortality worldwide.
  • Prolonged labour increases the risks of infection, uterine rupture, and neonatal distress.
  • Infants born preterm at greater risk for experiencing disorders ranging from blindness to cerebral palsy.
  • Prolonged labour can harm both mother and infant and lead to cesarean delivery.

Progesterone treatment aimed at preventing premature labour can help a subset of patients, but for other individuals, confounding factors may reduce effectiveness, noted Steve Wu, Ph.D., first author on the study and a staff scientist in DeMayo’s lab.

“Although labour stimulation by oxytocin infusion is an approved measure to mitigate labour dystocia, serious side effects have been associated with this treatment,” said Wu.
“Novel proteins that we identified as being part of progesterone signaling could serve as a key molecular switch of uterine contraction, through drug-dependent regulation of their activities,” he explained.

“Hormone signaling in pregnancy is complicated and involves both the hormone levels and the types of receptors in the uterus that sense the hormones,” said co-first author Mary Peavey, M.D., from the department of obstetrics and gynecology at the University of North Carolina at Chapel Hill.

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