How common is preterm birth?

About 1 in 10 babies in the United States is born preterm.

How can being born preterm affect my baby’s health?

Infants born preterm are more likely to have health problems, especially during the first year of life. These include:

• Problems with breathing, eating, and keeping warm

• Infections

• Movement and coordination problems

• Hearing and vision loss

• Slower growth and development compared to peers

• Behavioral problems and learning difficulties

Preterm babies may need to stay in a neonatal intensive care unit (NICU) to get special medical care. Once they leave the hospital, some babies need ongoing care to treat medical issues. Sometimes these problems last well into childhood.

What are the risk factors for or causes of preterm birth?

The following risk factors have been associated with preterm birth:

• Preterm birth in a previous pregnancy

• Lifestyle factors, including smoking, substance use, and low prepregnancy weight

• Having a lower income, living in a poorer area or neighborhood, and lack of access to prenatal care

• Getting pregnant less than 18 months after having a baby

• Having bacteria in the urine, a condition called bacteriuria, especially if it occurs without causing any symptoms

• Having a short cervix as measured by ultrasound

• Pregnancy complications such as preeclampsia, problems with the placenta, fetal growth restriction, and fetal genetic conditions

• Medical problems that existed before pregnancy, including high blood pressure, diabetes, and lupus

• Preterm labor (when labor contractions start too early) and premature rupture of membranes (when your water breaks before labor starts and it’s before 37 weeks)

• Being pregnant with twins, triplets, or more

Many pregnant people have at least 1 risk factor for preterm birth. Having a risk factor does not mean that you will have a preterm birth. Some risk factors, like smoking, can be changed. Others cannot be changed, such as having a previous preterm birth, but extra care during pregnancy may be recommended.

What are the signs and symptoms of preterm labor?

• Frequent, regular contractions that:

  • Occur 6 or more times in 1 hour

  • Cause your belly to tighten and harden and are uncomfortable

• Lower abdominal cramps or a low backache that gets worse or doesn’t go away

• A change in vaginal discharge (watery, bloody, or like mucous) or an increase in discharge

• Pelvic pressure (a feeling that the baby is pushing down)

• Your water breaks

• Bleeding with or without abdominal pain

What should I do if I have signs and symptoms of preterm labor?

If you have mild signs or symptoms, contact your healthcare provider right away. If your symptoms are severe or getting worse, you should go to the nearest hospital if you can do so safely. If you are worried about your safety or have heavy bleeding, call emergency services (911).   

How is preterm labor managed?

Sometimes preterm labor stops on its own. How your symptoms will be managed depends on your signs and symptoms, how far along you are (gestational age), and whether your cervix has started to open (dilate) or soften. 

• You will likely be admitted to the hospital. In some cases, you may be transferred to a hospital that can care for very preterm infants.

• A steroid medication may be given to prepare the fetus’s lungs and other organs for a possible early birth.  

• If you are less than 32 weeks pregnant, another medication called magnesium sulfate may be given to protect the fetal brain and nervous system. This medication has been shown to reduce rates of cerebral palsy and death in babies who are born before 32 weeks.   

• You may receive medications called tocolytics to try to slow down contractions. This gives time for the steroid injections or magnesium sulfate to take effect or for you to be moved to a hospital with a higher level of care.  

Can anything be done to prevent preterm birth?

Preterm birth prevention can start even before you become pregnant. Your healthcare provider can help you address any risk factors that could be changed, like stopping smoking or getting better nutrition.

During an early prenatal care visit, you will have a test to see if you have bacteria in your urine. The length of your cervix may be measured at the standard ultrasound exam between 18 and 23 weeks of pregnancy. If you are found to have a short cervix, treatment with vaginal progesterone may be recommended. This treatment has been shown to reduce the risk of preterm birth. This medication is also offered to people who have had a prior spontaneous preterm birth.

In some cases,  a procedure called cerclage may be recommended. In this procedure, a stitch is placed around the cervix to hold it closed. It is most often done through the vagina or, less frequently, with laparoscopy through the abdomen. With the abdominal approach, a cesarean delivery is needed. The approach used depends on many factors, such as how far along you are in pregnancy, your personal history of preterm birth or miscarriage, and the experience of your healthcare provider.