Advances in newborn medical care have greatly reduced the number of infant deaths that result from low birthweight, as well as the disabilities survivors of low birthweight experience. Still, a small percentage of survivors are left with problems such as mental retardation, cerebral palsy and impairments in lung function, sight and hearing. More than 60 percent of low-birthweight babies are preterm. The earlier a baby is born, the less it is likely to weigh, and the greater its risk for many problems. Their low birthweight results, at least partly, from slowing or temporary halting of growth in the womb.
Some babies are both premature and growth-retarded.
They are at high risk for many problems linked to low birthweight. We know some, but not all, of the reasons babies are born too small, too soon, or both. Fetal defects that result from inherited diseases or environmental factors may limit normal development. If the placenta is not normal, a fetus may not grow as well as it should. The mother's medical problems influence birthweight, especially if she has high blood pressure, diabetes, certain infections or heart, kidney or lung problems.