Premature Infant

Overview, Causes, & Risk Factors

Every newborn is classified at birth as one of the following: premature (less than 37 weeks gestation), full-term (37 to 42 weeks gestation), or post-term (born after 42 weeks gestation).

Preeclampsia, a condition that can develop in the second trimester of pregnancy with high blood pressure, fluid retention, and protein in the urine, may result in preterm labor. Other maternal disease processes such as kidney disease, diabetes, infection, or heart disease may also contribute to preterm labor. Often, the cause is unknown.

Multiple pregnancy (the presence of more than one fetus in the uterus, twins etc.) accounts for 15% of all premature births.

The problems encountered by a premature infant are related to the immaturity of the organ systems. The infant requires specialized care in a nursery until his or her organ systems have developed enough to sustain life without specialized support. Depending on the extent of prematurity, this may take weeks to months.

Common problems related to immature organ systems include:

• Respiratory complications such as hyaline membrane disease (also known as respiratory distress syndrome or RDS)
• Central nervous system immaturity that results in difficulty coordinating sucking and swallowing, susceptibility of bleeding into the brain, or episodes of absent breathing (apnea)
• Gastrointestinal immaturity that leads to feeding intolerance
• Kidney immaturity

Risk factors that may contribute to preterm labor include lack of prenatal care, poor nutrition, youth (mothers less than 18 years old), and substance abuse.

Problems inherent to the mother's health include:

• A history of a previous preterm delivery
• A high unexplained alpha-fetoprotein level in the second trimester
• Untreated disease or infection (such as urinary tract infection or infection of the amniotic membranes)
• Abnormalities of the uterus or cervix
• Premature rupture of the membranes or placenta previa

Approximately 10% of all births in the U.S. occur before 37 weeks gestation.