Gynecology & Obstetrics
Open Access

Preterm Birth

Premature birth is when a baby is born before the normal end of pregnancy. In humans, a pregnancy normally lasts for about nine months. On average, a pregnancy lasts for 266 days. Babies who are born before 37 complete weeks of pregnancy (calculated from the last menstrual period) are said to be premature. In the United States, about twelve percent of the babies are born prematurely (that is about one in every eight babies).  In 2003, there were over 490,000 premature births.

Worldwide rates of prematurity are more difficult to get. In developing countries, there is often no professional medical care for these babies. This makes it difficult to tell how far along the pregnancy really was. For this reason, the World Health Organization tracks rates of low birth weight instead. In 2000, 16.5 percent of babies born in developing countries were of low birth weight.It is estimated that one-third of these low birth weight deliveries are due to premature delivery. The risk of having a problem (called a complication) is higher in shorter pregnancies. Babies born prematurely die more often in their first year of life than others. Most such deaths occur in the first month of life, which is called neonatal mortality. Worldwide, prematurity causes ten percent of neonatal mortality, or around 500,000 deaths per year.[3] In the U.S., where many infections and other causes of neonatal death have been markedly reduced, prematurity is the leading cause of neonatal mortality at 25%.[4] Prematurely born infants are also at greater risk of developing serious health problems, such as cerebral palsy, chronic lung disease, gastrointestinal problems, mental retardation, vision loss, or hearing loss.[5] They are also more likely to have depression as teenagers.