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 (see Births in the United States, 2022). The preterm birth rate declined 1% in 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, the rate of preterm birth among African-American women (14.6%) was about 50 percent higher than the rate of preterm birth among white or Hispanic women (9.4% and 10.1% respectively).
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. Read Your Baby Grows Throughout Your Entire Pregnancy [PDF-312KB]. 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
- Hearing problems
Preterm births may also take an emotional toll and be a financial burden for families.
- Contractions (the abdomen tightens like a fist) every 10 minutes or more often
- Change in vaginal discharge (a significant increase in the amount of discharge or leaking fluid or bleeding from the vagina)
- Pelvic pressure—the feeling that the baby is pushing down
- Low, dull backache
- Cramps that feel like a menstrual period
- Abdominal cramps with or without diarrhea
If you think you are experiencing preterm labor, it is important that you see a healthcare provider right away. If you are having preterm labor, your provider may be able to give you medicine so that the baby will be healthier at birth.
Many times we do not know what causes women to deliver their babies early. However, several known factors may increase the likelihood that a woman could deliver early. Based on CDC Grand Rounds: Public Health Strategies to Prevent Preterm Birth, below are social, personal, and economic groups; pregnancy and medical conditions; and behavioral factors of women with high risk of early delivery.
Social, Personal, and Economic Groups
- Teens and women who become pregnant over age 35
- Black, Native Hawaiian or Other Pacific Islander, and American Indian or Alaska Native women*
- Women with lower incomes
Pregnancy and Medical Conditions
- Women who have had a prior preterm birth
- Women with an infection, including COVID-19
- Women carrying more than 1 baby (twins, triplets, or more)
- Women who use tobacco
- Women who use drugs
- Women experiencing stress
*Of note regarding racism and health, racism—both interpersonal and structural—negatively affects the mental and physical health of millions of people. The impact is pervasive and deeply embedded in our society—affecting where one lives, learns, works, worships and plays and creating inequities in access to a range of social and economic benefits—such as housing, education, wealth, and employment. These conditions—often referred to as social determinants of health—are key drivers of health inequities within communities of color, placing those within these populations at greater risk for poor health outcomes, including preterm birth.
Talk with your doctor about signs of preterm labor and what to do.
Preventing preterm birth remains a challenge because there are many causes of preterm birth, and because causes may be complex and not always well understood. However, pregnant women can take important steps to help reduce their risk of preterm birth and improve their general health. These steps are to—
- Quit smoking. For help quitting, see How to Quit Smoking
- Avoid alcohol and drugs
- Get prenatal care as soon as you think you may be pregnant and throughout the pregnancy
- Seek medical attention for any warning signs or symptoms of preterm labor
- Talk with your doctor or other healthcare provider about what interventions and monitoring are available if you had a previous preterm birth
Another step women and their partners can take to reduce the risk of preterm birth is waiting at least 18 months between pregnancies.
Women who conceive through ART are at higher risk for preterm birth, 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 Single Embryo Transfer.
Important growth and development occur throughout pregnancy—all the way through the final few weeks. Unless there is a medical need, delivery should not be scheduled before 39 weeks of pregnancy. Read: Your Baby Grows Throughout Your Entire Pregnancy [PDF – 2 MB].
CDC’s Division of Reproductive Health is engaged in a variety of activities to reduce preterm delivery and complications. CDC recently expanded support to 36 perinatal quality collaboratives (PQCs), which are state or multi-state networks of teams of healthcare providers and public health professionals working to improve the quality of care for mothers and babies. Funding supports the capabilities of PQCs to improve the quality of perinatal care in their states, including efforts to reduce preterm birth.
- Percentage of Births Born Preterm by State from CDC
- Birth Data (including preterm birth rates) from CDC
- Premature Babies – Information about health problems among and care of premature babies from the March of Dimes.