Preterm Birth

image of a mother holding a newborn

Preterm birth is when a baby is born too early, before 37 weeks of pregnancy have been completed. In 2018, preterm birth affected 1 of every 10 infants born in the United States. Preterm birth rates decreased from 2007 to 2014, and CDC research shows that this decline is due, in part, to declines in the number of births to teens and young mothers. However, the preterm birth rate rose for the fourth straight year in 2018. Additionally, racial and ethnic differences in preterm birth rates remain. For example, in 2018, the rate of preterm birth among African-American women (14%) was about 50 percent higher than the rate of preterm birth among white women (9%).

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 icon[PDF-312KB]. Babies born too early (especially before 32 weeks) have higher rates of death and disability. In 2017, preterm birth and low birth weight accounted for about 17% of infant deaths. Babies who survive may have

Preterm births may also take an emotional toll and be a financial burden for families.

Frequently Asked Questions: For Women and Their Families

In most cases, preterm labor (labor that happens too soon, before 37 weeks of pregnancy) begins unexpectedly and the cause is unknown. Like regular labor, signs of early labor are—

  • 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 an 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 a woman to deliver early, but several known factors may increase the likelihood that a woman could deliver early. This preterm birth infographic pdf icon[PDF – 561 KB] gives some examples of these factors by medical and pregnancy conditions, behavioral factors, and social, personal, and economic characteristics. Talk with your doctor about signs of preterm labor and what to do.

Social, Personal, and Economic Characteristics
Teens and women over age 35
Black race
Women with low income

Pregnancy and Medical Conditions
Prior preterm birth
Carrying more than 1 baby  (twins, triplets, or more)

Tobacco use
Substance use

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 the use of progesterone treatment 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 pregnanciesexternal icon.

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 in the CDC’s 2016 Assisted Reproductive Technology Report pdf icon[PDF – 5MB].

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 icon[PDF – 2 MB].

What is CDC’s Division of Reproductive Health doing to prevent preterm birth?

CDC’s Division of Reproductive Health is engaged in a variety of research and science to practice activities aimed at understanding and reducing preterm birth. CDC scientists are collaborating with many partners, including state health departments, university researchers, and other health care professionals to understand why preterm births occur and what can be done to help prevent them. Read about our preterm birth activities.

Public Health Grand Rounds

a physician's open hands and the words public health grand rounds

CDC’s Public Health Grand Rounds is a monthly webcast created to foster discussion on major public health issues. The November 2015 session, Public Health Strategies to Prevent Preterm Birth, discusses how concerted efforts to improve surveillance data, better medical care and prevention, and stronger public health partnerships, can accelerate progress in reducing preterm births and improving neonatal outcomes. View the archived presentation and publication

Related Links
  • Is It Worth It?external icon – Information from the National Child and Maternal Health Education Program to learn the benefits of waiting until 39 weeks to deliver.
  • Premature Babiesexternal icon – Information about health problems among and care of premature babies from the March of Dimes.