Premature Birth

A preterm, premature or “preemie” baby is a baby born too early, or about three weeks before their due date. A full-term pregnancy (fetal development) lasts about 40 weeks. Preterm birth occurs when a baby is born at 37 weeks or earlier.

Premature or early birth can pose serious health risks to a newborn baby. That’s because many organs like the brain, lungs and liver, are still growing and developing in the final weeks of pregnancy. A premature baby may have trouble staying warm or feeding and may be at risk for developmental delays later in life.

Fortunately, advances in medical technology make it likely that a premature baby can overcome these early obstacles and grow into a healthy child.

What are the different types of premature birth?

Healthcare providers consider a pregnancy to be full term when childbirth occurs at 39 weeks or later. Research shows that infants born after 39 weeks are less likely to spend time in a neonatal intensive care unit (NICU).

When a baby is born after 37 weeks but before 39 weeks, healthcare providers call it early term. This isn’t the same as prematurity.

Deliveries before 37 weeks are considered preterm or premature. Preterm births fall into four categories:

• Late preterm: Born between 34 and 36 weeks. Most premature births occur during this time frame.
• Moderately preterm: Born between 32 and 34 weeks.
• Very preterm: Born before 32 weeks.
• Extremely preterm: Born before 25 weeks.

How common is premature birth?

About 1 out of every 10 births in the U.S. is premature.

Rates of premature birth are increasing as more people become pregnant after age 35 and as assisted reproductive technologies (like IVF) more often result in multiple gestations and higher-risk pregnancies.

What week is preterm birth safe?

Typically, the earlier a baby is born, the higher the risk for health complications. This isn’t always the case, nor does it mean if your baby is born at 39 weeks, there’s no risk of complications. It just means that studies show a baby is more likely to be born healthy when it reaches at least 37 weeks of pregnancy before birth.