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Information for Moms-to-Be About the New Full-Term Pregnancy Definition

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Full Term Starts at 39 Weeks

The American College of Obstetricians and Gynecologists and the Society for Maternal Fetal Medicine announced new, more specific definitions for babies born between 37 weeks and 42 weeks.

In the past, a baby born anytime between 37 weeks and 42 weeks was considered “term.” A pregnancy is now considered full term at 39 weeks.

Early term is 37 weeks through 38 weeks and 6 days. Full term is 39 weeks through 40 weeks and 6 days. Late term is 41 weeks through 41 weeks and 6 days. Postterm is 42 weeks and beyond.

Why Does This Matter?

Research shows that babies do best when they are born between 39 and 40 weeks.

Babies born before 39 weeks are at risk for problems with breathing, feeding, and controlling their temperature. They are also more likely to spend time in the neonatal intensive care unit, develop infections, and have a learning disability.

What Does This Mean for My Pregnancy?

Waiting to deliver until at least 39 weeks, in a healthy pregnancy, gives your baby the time he or she needs to grow. Your baby’s lungs, liver, and brain go through a crucial period of growth period between 37 weeks and 39 weeks of pregnancy. Waiting until 39 weeks, now called full term, gives your baby the best possible chance for a healthy start in life. 

Sometimes, when there is a health risk to the mother or baby, planned deliveries before 39 weeks are necessary. However, in a healthy pregnancy, its best to wait until at least 39 weeks.

It is important to know these terms so you and your health care provider can talk about what is best for the health of you and your baby.

Video: Term Talk

A text alternative is available at

Where Can I Find Out More?

Learn more about why it’s worth it to wait until at least 39 weeks of pregnancy to deliver, if mom and baby are healthy.

Last Reviewed: 09/02/2014