Infants with LBW belong to two general categories: infants who have LBW due to premature birth, and infants with intrauterine growth restriction (low for gestational age), which is typically related to problems with placenta, maternal health, or to birth defects. To differentiate premature LBW from mature growth-retarded LBW several types of data are necessary and include obstetrical history, newborn physical examination, and examination for maturational age. In general, the LBW infants are four times likely than infants born with normal weight to die in their first month of life. These who survive are two to three times more likely to suffer from short and long-term disabilities [2–4].
The percentage of all newborns born with low weight in the United States is around 7%. However, percentage of the LBW infants is higher in minority groups, particularly African-Americans, and the percentage of the African-American babies born with LBW is more than double of that for the Caucasian-American newborns [1, 3].
Risk factors for LBW are largely preventable. They include poor maternal nutrition, adolescent pregnancy, use of alcohol and drugs, premature births, smoking, multiple births, and sexually transmitted diseases. The use of assisted reproductive technology additionally accounts for a disproportionate number of LBW and VLBW infants in the United States, which is partially due to increases in multiple gestations and higher rates of LBW among singleton infants conceived with this technology.