Mamas on Bedrest: Vaginal Progesterone Cuts Premature Births

December 23rd, 2011

I’m tossing yet another tidbit of information for Mamas on Bedrest to share and discuss with their doctors.

In a study published online on December 14, 2011 in the American Journal of Obstetrics and Gynecology, a coalition of researchers from around the world (United States, Austria, Brazil, Denmark, India, South Africa, Turkey, and the United Kingdom) concluded that vaginal progesterone, administered in the mid-trimester of pregnancy to women with shortened cervix detected via ultrasound, can cut their risks of preterm labor by as much as half.

I found this information very interesting given the current brouhaha over Makena (the progesterone injections used for prevention of preterm labor) and how progesterone is often used early in pregnancy for women with repeated miscarriages (my situation!).

The researchers reviewed data from 5 highly respected studies and evaluated the efficacy and safety of using vaginal progesterone for the prevention of preterm labor in the presence of cervical shortening with rates of neonatal morbidity and mortality.  Here are their findings:

  • Vaginal progesterone reduced the rate of birth at less than 33 weeks’ gestation by 42% . It also reduced the risk for birth at less than 35 weeks’ gestation by 31%  and less than 28 weeks’ gestation by 50% *.

  • Vaginal progesterone also improved the following outcomes: respiratory distress syndrome, a composite measure of neonatal morbidity and mortality, birth weight less than 1500 g, admission to neonatal intensive care unit and need for mechanical ventilation.

Given these outcomes, one would think that physicians and researchers across the board would be recommending that women receive progesterone if they presented with shortened cevix. But such was not the case. Two commentators felt that the data was not conclusive enough. Sarah Bradley, MD, clinical assistant professor of obstetrics and gynecology from the University of Wisconsin–Madison felt that the data was “murky”. Her position stemmed from the fact that different studies used different definitions for shortened cervix.  She also noted that many women had received a cervical cerclage (surgical stitch placed to keep the cervix closed) in addition to the progesterone and felt that it couldn’t be definitively stated that the progesterone was in fact the true reason that preterm labor was averted.

Aaron B. Caughey, MD, PhD, director of women’s health and chair of obstetrics and gynecology, Oregon Health Sciences University, Portland, had a similar comment on the definition of shortened cervix. He also felt that the meta-analysis really didn’t add any new information to what is already “standard of care”.

As a result, researchers recommend that women be advised of both treatments. While it is commonly recognized that either a cerclage or progesterone alone is often enough to prevent preterm birth, many women may elect to have both treatments and that is okay. Researchers also recommend that further research be undertaken to specify “shortened cervix” and to give specific measurements at which treatments are beneficial. They also recommend research to assess the effects of race, ethnicity, socioeconomic status, and maternal age on cervical shortening and preterm labor.

While I’m all in favor of evidenced based research, sometimes I think we analyze things to death.  We know that adequate progesterone levels are essential to maintaining a healthy pregnancy. We see progesterone used in early pregnancy, especially in cases where women have undergone fertility treatments and/or have luteal phase defects resulting in repeated miscarriage. We know that progesterone injections (Makena and compounded variations) are effective in prolonging pregnancy in the instances of preterm birth later in pregnancy but before 37 weeks gestation. So I am not surprised that using vaginal progesterone is effective in helping prolong pregnancy and prevent preterm birth in cases of shortened cervix.

But I am surprised that commentators are pulling up short in making the recommendation that vaginal progesterone be used in the mid-trimester. Is it really necessary to determine that progesterone alone will prevent preterm birth in the presence of a cerclage? Is it really so awful if a woman has a cerclage and uses vaginal progesterone if she has a shortened cervix? And while it will be nice to know how efficacious progesterone is in various races, ethnicities, socioeconomic levels and in women of advanced maternal age, must we wait to have all this data before making recommendations? Can’t we do the work concurrently? It has been shown that use of progesterone produces more good than harm, so why not use it as currently stated and make the specific recommendations as the study data becomes available?

Many will judge my opinion and I am fine with that. But I was a woman who had repeat miscarriages until we figured out that my progesterone levels were not adequate to support pregnancy to term (beyond 1st trimester actually!). I know women who benefited from having progesterone injections in the second and third trimesters to prolong their pregnancies. I think that I can safely say, It didn’t matter if we were white or black, rich or poor, “old” or young, if it helped us to maintain our pregnancies and have healthy babies, we were all for it! If it helps specific subgroups, even better.

But on behalf of high risk pregnant women everywhere, please don’t wait to use a treatment that has been shown to be safe and efficacious in preventing preterm birth just so that you can get “exact” data. If you know that progesterone is efficacious in preventing preterm birth in a woman who has a cervix of 20mm and has a cerclage, why not try it in a woman whose cervix is 15mm or even 10mm? If she is at such risk, why not try? As a physician and scientist, you may think that it’s a waste. But for the mama desperately hoping and praying for her baby, it’s hanging on to all hope by a thread. Please don’t cut us off.

*This post is a summary and commentary of the MedScape report and the published article in The American Journal of Obstetrics and Gynecology online journal. Statistical information was attenuated for ease of reading. To read the full study results, please read the complete texts provided here.

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