Preterm Birth

In 2012, preterm birth affected more than 450,000 babies—that's 1 of every 9 infants born in the United States. Preterm birth is the birth of an infant before 37 weeks of pregnancy. Preterm-related causes of death together accounted for 35% of all infant deaths in 2010, more than any other single cause. Preterm birth is also a leading cause of long-term neurological disabilities in children. Preterm birth costs the U.S. health care system more than $26 billion in 2005.

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 develop fully. 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—

Breathing problems.
Feeding difficulties.
Cerebral palsy.
Developmental delay.
Vision problems. [PDF - 118KB]
Hearing impairment.

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

Frequently Asked Questions: For Women and Their Families

The preterm birth infographic gives some examples of factors associated with preterm birth by medical and pregnancy conditions, behavioral factors, and social, personal, and economic characteristics.

[PDF - 2.3MB]

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

Several factors 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 poorly 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 (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. It is not intended for use in women carrying more than one baby or women with other risk factors for preterm birth. 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 2010 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 a doctor right away. If you are having preterm labor, the doctor 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, current research indicates that 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 research activities.