A premature infant is a baby born before 37 weeks gestation.

Preterm infant; Preemie; Premie

At birth, a baby is classified as one of the following:

• Premature (less than 37 weeks gestation)
• Full term (37 to 42 weeks gestation)
• Post term (born after 42 weeks gestation)

If a woman goes into labor before 37 weeks, it is called preterm labor. Often, the cause of preterm labor is unknown. Multiple pregnancy (twins, triplets, etc.) makes up about 15% of all premature births.

Health conditions and events in the mother may contribute to preterm labor. Examples are:

• Diabetes
• Heart disease
• Infection (such as a urinary tract infection or infection of the amniotic membrane)
• Kidney disease

Different pregnancy-related problems increase the risk of preterm labor:

• An "insufficient" or weakened cervix, also called cervical incompetence
• Birth defects of the uterus
• History of preterm delivery
• Poor nutrition right before or during pregnancy
• Preeclampsia -- the development of high blood pressure and protein in the urine after the 20th week of pregnancy
• Premature rupture of the membranes (placenta previa)

Other factors that make preterm labor and a premature delivery more likely include:

• African-American ethnicity (not related to socioeconomic status)
• Age (younger than 16 or older than 35)
• Lack of prenatal care
• Low socioeconomic status
• Use of tobacco, cocaine, or amphetamines

Review Date: 01/08/2010
Reviewed By: Kimberly G. Lee, MD, MSC, IBCLC, Associate Professor of Pediatrics, Division of Neonatology, Medical University of South Carolina, Charleston, SC. Review Provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)