What is preterm labor?

Preterm labor is labor that comes too early—between 20 and 37 weeks of pregnancy. In labor, the uterus contracts to open the cervix. This is the first stage of childbirth. In most pregnancies, this happens at 37 to 42 weeks. Preterm labor is also called premature labor.

Preterm labor doesn't always lead to preterm birth, but it may. A baby born too early may have serious problems, such as chronic lung disease. This is because many of the baby's organs, especially the heart and lungs, aren't fully grown yet. The earlier a baby is born, the higher the risk of problems.

What causes it?

Preterm labor can be caused by a problem involving the baby, the mother, or both. Possible causes of preterm labor include being pregnant with more than one baby, an infection, and problems with the placenta, uterus, or cervix. Often a combination of several factors is responsible. Sometimes the cause isn't known.

What are the symptoms?

It can be hard to tell when labor starts. But you may notice one or more symptoms, such as menstrual-like cramps, leaking or gushing of fluid from your vagina, or regular contractions. This means about 6 or more contractions in 1 hour, even after you've had a glass of water and are resting.

How is it diagnosed?

If you have symptoms of preterm labor, both you and your baby will be examined and monitored. You may have urine and blood tests to check for problems that can cause preterm labor. Your doctor or midwife will check the baby's heartbeat and do an ultrasound to see how your baby is doing.

How is preterm labor treated?

Preterm labor isn't always treated. When deciding whether and how to treat it, many things are considered, including your health and your baby's age, weight, and health. Your doctor or midwife may use medicine to try to delay the birth or medicines to prevent infection and prepare your baby for birth.