Small for gestational age (SGA) describes infants who weigh less than they should given their gestational age (the weeks they have spent in the uterus).

SGA infants can be premature, full-term, or post- term; such infants are simply not as large as would be predicted by their maturity. Experts differ on whether the cutoff for being small for gestational age (SGA) should be the third percentile or the tenth percentile for weight. Being SGA is not a disease in itself, but rather a risk factor for developing problems during the perinatal period as a result of having experienced smaller-than-expected growth in the womb.

Causes

Although underlying fetal problems cause some infants to be SGA, in the vast majority of SGA infants, the condition is caused by an inadequate supply of oxygen or nutrients before birth. Uterine environmental problems that can lead to...