Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to page options Skip directly to site content

Preterm Birth

Newborns in nurseryPreterm birth is the birth of an infant before 37 weeks of pregnancy. In 2014, preterm birth affected about 1 of every 10 infants born in the United States. Preterm birth is the greatest contributor to infant death, with most preterm-related deaths occurring among babies who were born very preterm (before 32 weeks). Preterm birth is also a leading cause of long-term neurological disabilities in children.

A developing baby goes through important growth during the final weeks and months of pregnancy. Many organ systems, including the brain, lungs, and liver need the final weeks of pregnancy to fully develop. Read Your Baby Grows Throughout Your Entire Pregnancy [PDF-312KB]. There is a higher risk of serious disability or death the earlier the baby is born. Some problems that a baby born too early may face include—

Preterm births also may cause emotional and economic burdens for families. Learn more about preterm birth.

Frequently Asked Questions: For Women and Their Families

Are some women more likely than others to go into preterm labor and deliver early?

Several factors, including ones that researchers have not yet identified, may increase the likelihood that a woman has preterm labor and delivers early. This preterm birth infographic [PDF - 2.3MB] gives some examples of these factors by medical and pregnancy conditions, behavioral factors, and social, personal, and economic characteristics. 

Can anything be done to prevent a preterm birth?

Preventing preterm birth remains a challenge because the causes of preterm births are numerous, 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 in quitting, call 1-800-QUIT-NOW (1-800-784-8669) or visit Tobacco Use and Pregnancy: Resources
  • Avoid alcohol and illicit 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

What are the warning signs of preterm labor?

In most cases, preterm labor 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

My last baby was born early. Is there anything I can do in this pregnancy to keep it from happening again?

A progesterone medication (17-alpha hydroxyprogesterone caproate, or 17P) may prevent preterm birth among women who have had a prior preterm birth. The U.S. Food and Drug Administration (FDA) approved hydroxyprogesterone caproate injection (Makena™) to reduce the risk of preterm delivery in pregnant women with a history of delivering early. Consult with your health care provider to learn more about this and other drugs, including whether they are safe for use during pregnancy.

I used in vitro fertilization (IVF) or another assisted reproductive technology (ART) to get pregnant. What is my risk of having a preterm birth?

Women who conceived 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 cycles and preterm birth can be found in the CDC’s 2012 Assisted Reproductive Technology Report.

What should I do if I think I’m experiencing preterm labor?

If you think you are experiencing preterm labor, it is important that you see an obstetric care 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.

Is it okay to schedule my baby’s birth once I reach 37 weeks gestation?

Important growth and development occur throughout pregnancy—all the way through the final few weeks. If the mother is healthy and there are no pregnancy complications indicating a need for earlier delivery, delivery should not be scheduled before 39 weeks gestation.

Read: Your Baby Grows Throughout Your Entire Pregnancy [PDF-312KB]

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 births. 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 Roundsgrand rounds image

CDC’s Public Health Grand Rounds is a monthly webcast created to foster discussion on major public health issues. Save the date for the next Grand Rounds session, “Public Health Strategies to Prevent Preterm Birth”, on Monday, November 16, 2015 at 10AM ET. A live external webcast will be available.

Related Links

  • Video: Is It Worth It? Watch this video from the National Child and Maternal Health Education Program to learn the benefits of waiting 39 weeks until delivery.
  • Preterm Birth (March of Dimes) The March of Dimes continues its national campaign to help families and communities cope with prematurity.
  • First Candle First Candle is dedicated to safe pregnancies and the survival of babies through the first years of life.
  • Preterm Births The National Library of Medicine (NLM) provides information for health care consumers on preterm births and related topics in maternal and child health.
  • Preterm Labor and Birth (ACOG) [PDF - 282KB] This patient education pamphlet was developed by the American College of Obstetricians and Gynecologists (ACOG).
  • Video: Who’s Leading the Health Indicators? Webinar: Maternal, Infant, and Child Health. This presentation discusses preterm birth and infant mortality and features Dr. Howard Koh, previous HHS Assistant Secretary for Health, Ohio Perinatal Quality Collaborative leadership, and Dr. Zsakeba Henderson of the Centers for Disease Control and Prevention.