How does progesterone work?

Having a short cervix can be scary, and being prescribed a new medication doesn’t always feel reassuring right away, either. Knowing how that medication can be used to help reduce the risk of preterm labor and birth can be helpful when it comes to feeling better about having a new medication in your life. This is especially true of vaginal progesterone,which can feel intrusive.

What is progesterone?

Progesterone, the medication, is the synthetic form of the hormone progesterone, which the body produces naturally. During early pregnancy, progesterone supports the growth of the uterus, and keeps it from having contractions. Later on in pregnancy, progesterone is a part of the process as the breasts start to produce milk, and it supports the lungs as they work to produce enough oxygen for a second pair of lungs.

Previously progesterone was offered in the form of the shot Makena, however, this is no longer standard of care. Vaginal progesterone is now offered to people with a risk of preterm birth due to a shortened cervix. People with a cervix that measures less than or equal to 25mm during their 18-22 week ultrasound will likely be offered vaginal progesterone to reduce the risk of preterm labor. Sometimes, progesterone is also prescribed for a history of miscarriages and bleeding in early pregnancy. 

Vaginal progesterone

Vaginal progesterone is prescribed after diagnosis of a short cervix, up until 37 weeks gestation, as a defense against preterm labor. Vaginal progesterone is taken as a gel, suppository, or capsule, placed in the vagina using an applicator that looks somewhat like a tampon.

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