Since 2003, research studies have found that treatment with the hormone progesterone reduces the rate of premature birth among some women.

The American College of Obstetricians and Gynecologists recommends that progesterone be given when:  

• A woman is currently pregnant with one baby and
• She previously delivered a baby before 37 completed weeks of pregnancy. Either labor began on its own, without the use of drugs or other methods, or the  membranes surrounding the baby in the woman’s uterus ruptured too early.

ACOG says that progesterone may also be given to women who have a short cervix.

Studies to date have not reported serious side effects from progesterone for either mother or baby. Progesterone treatment does not appear to increase the risk of birth defects or developmental problems in the baby (through the first 2 years of life). Longer-term follow-up of study participants has not been done.

The studies use two forms of progesterone, an injected form (17P) and a vaginal form (suppositories or creams):

• 17P treatment: Women getting 17P shots to help prevent another premature birth start receiving them between 16 and 20 weeks of pregnancy and continue weekly until 37 weeks. Health care providers must order 17P through special pharmacies that are licensed to mix custom medicines.
• Treatment with vaginal progesterone: Researchers are seeking to determine whether vaginal progesterone treatment works as well as 17P shots in preventing another premature birth. The woman inserts a suppository or cream each night before bedtime.

If you have already had a premature baby or you have a short cervix, ask your health care provider if progesterone treatment might be a good choice for you.

Health care providers must order 17P and vaginal progesterone from special pharmacies. This may delay treatment or affect the availability of treatment.

Will Insurance Pay for Treatment?
Not all private insurance companies or state Medicaid programs pay for progesterone treatment. Check with your insurer before starting treatment. Your doctor may also be able to provide information.

This article is based, in part, on guidelines provided by the American College of Obstetricians and Gynecologists (ACOG).

Juy 2009