Preterm Birth

At a glance

Preterm birth is when a baby is born too early, before 37 weeks of pregnancy have been completed. In 2022, preterm birth affected about 1 of every 10 infants born in the United States.

Woman holding preterm infant in a hospital setting

Preterm birth rates

The preterm birth rate declined 1% from 2021 to 2022, to 10.4%, following an increase of 4% from 2020 to 2021. However, racial and ethnic differences in preterm birth rates remain. In 2022, preterm birth among Black women (14.6%) was about 50% higher than White (9.4%) or Hispanic women (10.1%).

Health problems related to preterm birth

A developing baby goes through important growth throughout pregnancy─ including in the final months and weeks. For example, the brain, lungs, and liver need the final weeks of pregnancy to fully develop. Unless there is a medical need, delivery should not be scheduled before 39 weeks of pregnancy.

Babies born too early (especially before 32 weeks) have higher rates of death and disability. In 2021, preterm birth and low birth weight accounted for about 14.8% of infant deaths (deaths before 1 year of age). Babies who survive may have breathing problems, feeding difficulties, cerebral palsy, developmental delay, vision problems, and hearing problems. Preterm births may also take an emotional toll and be a financial burden for families.

What to do if you're experiencing preterm labor

Preterm labor is labor that happens too soon, before 37 weeks of pregnancy. If you think you are experiencing signs of preterm labor, see a health care provider right away. Your provider may be able to give you medicine so that the baby will be healthier at birth.

Factors associated with preterm birth

Many times we do not know what causes women to deliver their babies early. Several factors may increase the likelihood that a woman could deliver early.1 Below are groups with higher rates of preterm birth.

Demographic or social characteristics

  • Teens.
  • Women who become pregnant over age 35.
  • Black women.*
  • Native Hawaiian and Pacific Islander women.*
  • American Indian or Alaska Native women.*
  • Women with lower incomes.
  • Women experiencing stress.

Pregnancy and medical conditions

Behavioral characteristics

  • Women who use tobacco.
  • Women who use drugs.

* Race is a social construct, meaning it is an idea that has been created and accepted by people in a society. It is not a biological driver of differences in preterm birth.

Talk with your doctor about signs of preterm labor and what to do.

Preventing preterm birth

Preventing preterm birth remains a challenge because causes may not always be well understood. However, pregnant women can take important steps to help reduce their risk of preterm birth and improve their general health:

  • Quit smoking. For help quitting, see How to Quit Smoking.
  • Avoid alcohol and drugs.
  • Get prenatal care early and throughout pregnancy.
  • Seek medical attention for any signs or symptoms of preterm labor.
  • Talk with your doctor if you had a previous preterm birth.

Another step women and their partners can take to reduce the risk is to wait at least 18 months between pregnancies.

Risk of preterm birth after conceiving using IVF

Women who conceive through in vitro fertilization (IVF) or another assisted reproductive technology (ART) are at higher risk for preterm birth. This is primarily because they are more likely to be pregnant with more than one baby at a time. More detailed information on ART and preterm birth can be found at this page on Single Embryo Transfer.

CDC activities

Perinatal Quality Collaboratives

CDC's Division of Reproductive Health recently expanded support to 36 Perinatal Quality Collaboratives (PQCs). Funding supports the capabilities of PQCs to improve the quality of perinatal care in their states. This includes efforts to reduce preterm birth.

Sources of CDC preterm birth data

National Center for Health Statistics

Assisted Reproductive Technology (ART) Surveillance

Pregnancy Risk Assessment Monitoring System

Related links

  1. Shapiro-Mendoza CK, Barfield WD, Henderson Z, et al. CDC Grand Rounds: Public Health Strategies to Prevent Preterm Birth. MMWR Morb Mortal Wkly Rep. 2016; 65(32):826–830.