According to the Center for Disease Control, over one in every 10 infants born in the United States in 2021 was born preterm. Preterm birth isn’t just an issue in the United States, either; it is a widespread issue across the globe and the leading cause of many developmental problems in infants. Because preterm birth is difficult to predict and can cause serious fetal complications, experts have developed ways to lower a woman’s risk of preterm labor and birth when there’s a risk of preterm birth.
Progesterone is one tool that healthcare providers commonly use to reduce a woman’s risk of preterm labor.
What is progesterone?
Progesterone is a hormone that the body produces naturally. Progesterone helps thicken the uterus to prepare for the fertilized egg before a woman becomes pregnant. About 8-10 weeks into pregnancy, the placenta begins to produce progesterone to keep the uterine lining maintained. Progesterone helps with breast development and complements estrogen production.
Why is progesterone helpful in preventing preterm labor and birth?
In addition to what’s described above, progesterone also keeps the uterus from contracting during pregnancy. Contractions before 20 weeks of pregnancy can lead to fatal consequences for the fetus, so a steady supply of progesterone is needed to prevent early contractions.
Who is prescribed progesterone?
If you have a short cervix, the hormone progesterone may be an important part of the line of defense.
Some research suggested that progesterone treatment was helpful for those with a history of prior preterm birth, and that getting weekly progesterone injections would lower the risk of preterm labor. However, the PROLONG study published in 2020 found that weekly progesterone injections did not have a significant benefit for those with a history of preterm birth. Because the evidence is mixed, if you have a history of preterm birth, talk through the possible benefits and risks of progesterone treatment with your healthcare provider.
Progesterone is not recommended if you’re having twins or multiples and are at risk for preterm birth.
When and how is progesterone administered?
The timing and method of progesterone application depend on a variety of factors. There are different forms of progesterone that a woman can take for pregnancy.
- Progesterone shots, also called 17-hydroxyprogesterone. These are usually given to women who have previously had a spontaneous preterm birth, and who are carrying only one baby. These are usually administered weekly beginning between 16 and 20 weeks gestation, through until 36 weeks gestation.
- Vaginal progesterone. Vaginal progesterone is prescribed to women with a specific degree of short cervix who are carrying just one baby. This can come in the form of gel, suppositories, or capsules, and is administered directly into the vagina daily. Treatment usually starts between weeks 16 and 24, and lasts until week 36 of pregnancy. Vaginal progesterone has been shown to effectively reduce the risk of preterm birth in women with a short cervix typically measuring less than 2 centimeters.
Progesterone isn’t prescribed to everyone who is at risk for preterm birth. Depending on your pregnancy characteristics and prior history, your provider may or may not recommend progesterone. Speak to your healthcare provider if you have any questions about whether or not progesterone would help your pregnancy.
Reviewed by the Ovia Health Clinical Team
- “What is premature birth?” CDC. US Department of Health and Human Services, Nov 9 2015. Web.
- Society for Maternal-Fetal Medicine Publications Committee. “Preterm birth: Progesterone as treatment for preterm birth.” American Journal of Obstetrics and Gynecology. 206(5)376-386. Web. May 2012.
- “Progesterone and pregnancy: a vital connection.” RESOLVE. RESOLVE: The National Infertility Association Since 1974, 2016. Web.
- Ana Gotter. “Low progesterone: causes, complications, and more.” Healthline. Healthline Media, Aug 25 2016. Web.