When Do Pregnant Women Need Progesterone Shots?

I’m pregnant. I've heard that progesterone shots can prevent early labor. Should I get them?
– Izzy

If you've had a premature baby in the past, your doctor may prescribe progesterone shots during your current pregnancy to help prevent early labor.

Babies born too early (before 37 weeks of pregnancy) can have health problems, including:

• breathing and feeding problems
• vision problems
• learning problems

Some premature babies do not survive.

The progesterone shot (sometimes called "17P" for the drug name [17 alpha-hydroxyprogesterone caproate] or its brand name, Makena®) can increase a woman's chances of having a full-term baby.

17P has the hormone progesterone in it, which helps prevent contractions. The uterus contracts during labor to help "push" a baby out of the womb for delivery. 

Doctors recommend starting 17P shots during the second trimester of pregnancy, usually between 16 and 20 weeks. Shots are given by a health care provider in the hip or thigh area. They are given until 37 weeks.

As with any shot, there's a risk of minor side effects like redness and soreness at the shot site. Rarely, some women get blood clots or have allergic reactions.