Low birthweight is defined as being less than 2500 grams (or 5.5 pounds) at birth, with premature birth being a common cause of such low birthweight babies.

Birthweight is one of the key indicators of the health and viability of a newborn infant. It is one of the leading causes of infant mortality. Low birthweight infants are 40 times more likely to die in their first month of life than normal birthweight infants. They are also twice as likely as other infants to exhibit health problems and serious developmental delays during childhood.

Several factors contribute to low birthweight. These include teenage pregnancies, unwanted or unintended pregnancies, lack of prenatal care, poor nutrition during pregnancy leading to poor maternal weight gain, maternal smoking, and the use of alcohol and other drugs during pregnancy. All of these factors are preventable, and are called "preventable risk factors."

Maternal age, maternal health, fetal...