Progesterone to Prevent Preterm Labor


I’m about 23 weeks along and have a history of preterm labor with a couple of my previous pregnancies (four out of my five children before this pregancy were premature).
It has been suggested by a high-risk doctor that I should get the progestrone injection every week to reduce the the risk of preterm labor. I’m very nervous because I have never heard of this before and when I did research on the web, no one knew the long-term effect on both the mother and baby. I worry about the side effects.

Can you please put my mind to rest by giving me any information about the progestrone injection? I still don’t know what to do. Also, by next Friday, I will be starting the fetal fibronectin test which will let me know if I’m going into labor in the next two weeks. Should I wait for another week to get this test before getting the progestrone injection? If the test is negative then I don’t think I need the injection, right?

I’m very anxious, please help me. I’m praying but am not sure what to do.

Thank you for your help.



Dear Faustina,

There have been a number of studies demonstrating that progesterone, or a similar hormone 17-alpha hydroxyprogesterone caproate (17-OHPC), can reduce the incidence of premature labor by at least one-third in women with a history of premature labor. Progesterone can help prevent first and second trimester miscarriages, as well as prevent preterm labor once the baby is viable, in women with low progesterone levels. Bioidentical progesterone, the same as the hormone progesterone produced in large quantities by the placenta, can be injected twice weekly, and calms the uterus. Progesterone vaginal suppositories have also been shown to be effective, but must be used twice daily. In the U.S. it is more common to use the synthetic hormone 17-OHPC, since it can be injected weekly rather than twice a week. In fact, there have been editorials in medical journals chiding high risk obstetrical units for not using this therapy enough!

Other interventions that help reduce the rate of premature labor are consuming fish oil 2000 mg. daily, aggressively treating bacterial vaginal infections with oral antibiotics, and placing a cervical cerclage (a stitch in the cervix) to prevent premature delivery in vulnerable women.

There is no risk from using bioidentical progesterone in the second and third trimesters to prevent preterm labor, as it is identical to the progesterone produced by your own body. A Cochrane Review in 2006 concluded that there have not been sufficient studies on 17-OHPC, although most high-risk pregnancy physicians believe it is beneficial.

I believe the best therapy is to use bioidentical progesterone according to the protocol created by the Pope Paul VI Institute in Omaha, which replicates ideal levels of progesterone in pregnancy. Ideally, progesterone levels should be checked every four weeks or so to check the dose. The dose of progesterone used is 100-200 mg intramuscularly every three to four days. It helps to use a concentrated solution of progesterone, 100 mg./ml, which can be obtained by your physician from Kubat Pharmacy in Omaha, Nebraska. If you contact CANFP, we can send you a copy of the Pope Paul VI Institute Protocol that will help keep your progesterone levels at the proper level.

Best wishes for a nine-month pregnancy!

Mary L. Davenport, M.D.

Answered By:

Mary Davenport, MD, MS
Mary Davenport, MD, FACOG, an obstetrician/gynecologist from the Oakland Region of California, offers telehealth services over She graduated from Tufts University School of Medicine and completed her residency at UC San Diego. Dr. Davenport is a Fellow of the American College of Obstetrics and Gynecology, and serves on the Advisory Board of the California Association of Natural Family Planning.

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