Progesterone does not prevent pre-term birth or complications

03 October 2017
Premature baby

An increasingly popular hormonal “treatment” for pregnant women with a history of preterm birth does not work, a major new international study shows.

The research looked at the practice of giving progesterone pessaries to pregnant women who have previously given birth before 37 weeks.

Earlier evidence had suggested that this treatment could delay birth, reducing the risk and severity of complications affecting babies born too early, while also improving the mothers’ health.

However, this latest study, a large double-blind randomised trial called PROGRESS, has disproved that notion.

The University of Auckland’s Professor Caroline Crowther says the results are important.

“We now have a clear answer we can believe: vaginal progesterone does not improve the baby’s health when given to women who have had a history of a previous preterm birth,” she says.

The PROGRESS study involved a total of 789 women from 39 Australian, New Zealand, and Canadian maternity hospitals.

Half the women were randomised to give themselves progesterone pessaries for 14 weeks starting at mid-pregnancy, while the other half used the matching placebos.

Researchers then assessed the health of the babies and their mothers.

The rate of health problems in the babies was not significantly different between the two treatment groups. The mother’s health and side effects of treatment were also overwhelmingly similar.

Professor Crowther says the PROGRESS study now gives certainty on a treatment option to follow.

“There have been mixed findings from recent studies – some show the use of vaginal progesterone reduces the risk of preterm birth, while others don’t and there has been uncertainty about the health benefits. Without a consensus, treatment practices vary widely across hospitals and countries.

“This is good for pregnant women and health practitioners to know, so they won’t waste time and resources on an ineffective treatment,” Professor Crowther says.

The PROGRESS findings, published in high-ranking journal PLOS Medicine, match those from two other recent large, randomised studies.

Commenting in the same journal, Jane Norman from the University of Edinburgh and Phillip Bennet from the Imperial College London argue this growing body of evidence justifies a thorough review of all progesterone studies, and exploring other alternatives for preventing premature birth.

You can read the full study on progesterone and pre-term birth here.