How does progesterone work?

The risk of preterm birth can be scary, and being prescribed a new medication to treat a scary health condition doesn’t always feel reassuring right away, either. Knowing how that medication can be used to help reduce the risk of preterm labor and delivery can be helpful when it comes to feeling better about having a new medication in your life. This is especially true of progesterone, which is either delivered daily and vaginally, which can feel intrusive, or weekly as a shot.

What is progesterone?

Progesterone the medication, which is generally prescribed to pregnant women in the form of the shot Makena or vaginally as a suppository, gel, or capsule, is the synthetic form of progesterone the hormone, which the body produces naturally. During pregnancy, naturally produced progesterone helps out in early pregnancy by helping the uterus grow, and keeping it from having contractions while it does. 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.

Sometimes, when progesterone is prescribed in a medication, it’s specifically because a doctor has detected that the mother’s body isn’t producing enough on its own. Other times, it’s because the mother has other risk factors that make preterm labor more likely, like having a short cervix detected on a transvaginal ultrasound.

Vaginal progesterone

Vaginal progesterone is sometimes prescribed early in a pregnancy to women at a high risk of miscarriage, and in others is prescribed from mid-way through the second trimester, up through the due date, 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.

Progesterone as an injection

Like all shots, the progesterone injection carries the risk of swelling and pain around the site of the injection, which is usually in the hip or thigh area. Many healthcare providers recommend getting up and walking around after getting a progesterone shot, to get circulation going, and keep a knot from forming at the site.

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