Medicines for preterm labor

Preterm labor is labor that happens too early, before 37 completed weeks of pregnancy. If you have preterm labor, your health care provider may give you medicine to try to stop your contractions and help prevent health problems in your baby.

What kinds of medicines are used during preterm labor?

There are three kinds of medicines your provider may give you if you’re having preterm labor. They include:

  1. Antibiotics. These kill infections caused by bacteria. You may need antibiotics if you have Group B strep infection or if you have preterm premature rupture of membranes (also called PPROM). PPROM is when the sac around your baby breaks early, before 37 weeks of completed pregnancy, causing labor to start.
  2. Corticosteroids. These speed up your baby’s lung development. They also greatly reduce the risk of death and health problems in your baby, such as respiratory distress syndrome, bleeding in the brain (called intraventricular hemorrhage) and infection in your baby’s intestines (called necrotizing enterocolitis).
  3. Tocolytics. These slow or stop labor contractions. Tocolytic medicines may delay labor, often for just a few days. This delay may give you time to get treatment with corticosteroids or to get to a hospital with a neonatal intensive care unit (NICU). This is part of a hospital that takes care of sick newborns.

Sometimes these medicines may cause side effects for you and your baby. Side effects are different for every woman and depend on the kind of medicine you get. Your provider can help you decide which medicine is best for you and your baby. For example, if you have a health condition, like a heart problem or severe preeclampsia, some tocolytics may not be safe for you.

Here are some medicines used during preterm labor and possible side effects for mom and baby:

Last reviewed October 2012

Most common questions

Am I at risk for preterm labor?

No one knows for sure what causes a woman to have preterm labor. But if you have certain risk factors, you're more likely than a woman without risk factors to have preterm labor. Risk factors include: having already had a premature baby or getting pregnant again too soon after having a baby; being pregnant with twins or more; and having problems with your uterus or cervix. You're more likely to have preterm labor if you're underweight or overweight or if you have health problems, like high blood pressure, diabetes or certain infections. Things in your life like stress, smoking, drinking alcohol and using drugs also put you at risk. Talk to your provider if you have any of these risk factors. You may be able to reduce your risk and have a better chance for a healthy pregnancy.

How do I know I’m in labor?

You'll know you're in labor if:

  • You have strong and regular contractions that last 30 to 60 seconds and come 5 to 10 minutes apart.
  • Your water breaks. Your baby has been growing in amniotic fluid (bag of waters) in your uterus. When the bag of waters breaks you may feel a big rush of waters or you may feel just a trickle.
  • You bleed a little from your vagina. This is called bloody show.

If you think you're in labor, call your health care provider, no matter what time of day or night.

How early can a baby be born and live?

There is no set timeline for survival for babies born early. Babies born earlier than 23 weeks have a much smaller chance of survival than babies born after 23 weeks.


About 9 out of 10 babies born at 28 weeks survive. But many have serious health problems. Any baby born before 37 completed weeks of pregnancy is considered premature. Premature babies have less time to develop in the womb than babies who arrive on time. This puts them at greater risk of medical and developmental problems. Every extra day in the womb helps the baby develop and mature and probably improve his or her health and development later in life. Between 23 and 26 weeks, every extra day in the womb increases a baby's chance of survival by 2 to 4 percent.

©2013 March of Dimes Foundation. The March of Dimes is a non-profit organization recognized as tax-exempt under Internal Revenue Code section 501(c)(3).