Premature or preterm labor is labor that starts early, before week 37 of pregnancy begins.

Around 1 in 10 babies are born prematurely in the United States, according to 2018 statistics.

Many healthy babies are born prematurely. Overall, however, the earlier a baby is born, the higher the risk of health problems and the need for a longer hospital stay.

Below, we look at the signs of preterm labor, what to do if it seems to be starting, the next steps for doctors, and how to reduce the risk.

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As the March of Dimes report, the following can be signs of premature labor:

  • more vaginal discharge than usual
  • changes to discharge, which may be bloody, watery, or have mucus in it
  • pressure in the pelvis or lower abdomen
  • lower back pain, particularly if it is constant
  • belly cramps, which may occur with diarrhea
  • regular or frequent contractions, which may be painful
  • the water breaking

Anyone who experiences one or more of these signs should contact a healthcare professional immediately or go to the hospital.

Doctors sometimes cannot tell why labor begins early. Overall, a wide range of factors can increase the risk.

General risk factors

The following can increase the chances of premature labor:

  • having a history of preterm labor
  • being pregnant with twins, triplets, or more
  • having a mother or sister who gave birth prematurely
  • having vaginal bleeding in the second or third trimesters
  • having a low socioeconomic status
  • having to stand a lot at work
  • being older than 35 or younger than 17
  • experiencing domestic abuse
  • being exposed to harmful chemicals, such as paint, secondhand smoke, air pollution, or lead
  • being underweight or overweight before pregnancy
  • not gaining enough weight during pregnancy
  • missing prenatal appointments or scans
  • becoming pregnant again within 18 months of giving birth
  • having a child with a heart or neural tube abnormality, such as spina bifida
  • becoming pregnant with in vitro fertilization, or IVF
  • drinking alcohol, using drugs, or misusing prescription drugs

Underlying health conditions

Certain health issues can increase the risk of premature labor and birth. These include:

Certain infections, such as toxoplasmosis, are more harmful during pregnancy than at other times, and they can raise the risk of premature labor and birth.

A person can develop toxoplasmosis by handling cat feces or eating undercooked meat.

A person cannot avoid certain factors that increase the risk of preterm birth, such as age or family or birth history.

However, a person can take the following steps to reduce the effects of other risk factors:

  • Get to know the signs of preterm labor and have a plan about contacting the doctor or visiting the hospital right away if the signs arise.
  • Attend every prenatal appointment, checkup, and scan, even if the pregnancy is going smoothly.
  • Maintain a healthy weight before and during the pregnancy.
  • Work with a member of the medical team to treat and manage any underlying health issues. A doctor may need to adjust or change a person’s medication plan during pregnancy.
  • Try to reduce stress, for example by practicing relaxation techniques.
  • Leave at least an 18-month gap between pregnancies.
  • Take care to avoid things that can cause infection, such as cat feces and contact with sheep, pigs, and rodents.
  • Avoid foods with a high risk of contamination, such as soft cheeses and raw meat.
  • Quit smoking and avoid alcohol and drugs. A member of the healthcare team can provide helpful resources and guidance.

Learn which foods to eat and avoid during pregnancy here.

If a person has a higher risk of preterm labor, a doctor may recommend:

Cerclage, or cervical stitch

If a healthcare professional finds that a person has a “weak cervix,” they may recommend a procedure to strengthen it and keep it from opening too early.

The procedure involves making a temporary stitch in the cervix that doctors usually remove when the pregnancy is full term, at 37 weeks, or when delivery is imminent.

A 2017 systematic review of 15 studies found that having cerclage was associated with a reduction in preterm birth among people with high-risk pregnancies.

A doctor may recommend cerclage for people with:

  • a history of second-trimester pregnancy loss due to preterm delivery
  • painless dilation in the second trimester
  • cervical shortening and a history of preterm birth

Extra monitoring

If a person has a higher risk of preterm labor, the healthcare team may recommend extra monitoring and scans so that they can spot and address any issues quickly.

If a person may be experiencing preterm labor, contact a healthcare professional or take them to the hospital as soon as possible.

A medical team member will assess whether labor has begun by checking the cervix and testing amniotic fluid levels, for example.

They may use an ultrasound scan, a transvaginal scan, or both to check the position of the baby and the length of the cervix, which changes during labor.

They may also test for fetal fibronectin, a protein that “glues” the amniotic sac to the uterus wall. The presence of the protein in urine indicates that labor is underway.

If a doctor confirms that labor has started, what happens next may depend on how far the labor and the pregnancy have each progressed. They may recommend:

Antenatal corticosteroids

Corticosteroids can help the baby’s lungs and other vital organs develop faster in preparation for life outside the womb.

They are most effective in weeks 24–34 of pregnancy. A doctor usually administers corticosteroids over a few days. They are not a long-term treatment.


Antibiotics help protect the baby from bacterial infections, such as a group B streptococcal infection.

A pregnant person usually receives these as a preventive measure during preterm labor if the doctor knows or is unsure whether they have this type of infection.


If the pregnancy has lasted 24–34 weeks, there are no signs of infection, and the amniotic sac has not ruptured, the doctor may try to slow down the labor with tocolytics.

These medications may help delay delivery for a few days, typically so that the person can receive steroids. However, there may be short-term side effects for the person and their baby.

About 1 in 10 pregnancies in the U.S. result in preterm birth, and doctors are sometimes unsure of the cause. A wide range of risk factors and underlying conditions can increase the chances of it happening.

There are several ways to reduce the risk of preterm labor, including taking steps to prevent infection, maintain a healthy weight and diet, and relieve stress. Receiving safe, effective treatment for any underlying conditions and attending all prenatal appointments can also help.

Various medical techniques and treatments can prevent or delay preterm labor and help prepare the baby for life outside the womb. However, while the goal is to safely prolong the pregnancy, it may only be possible to do so for a few days.