How trimester of entry into prenatal food program affects birth weight.

During 1988, 80% of women in the Special Supplemental Food Program for Women, Infants, and Children (WIC) in Texas enrolled in the program after the first trimester of pregnancy. Infants born to these women displayed higher rates of low birth weight than those born to women who entered WIC during their first trimester. Infants born to women who enrolled in WIC during the second trimester had higher birth weights than those born to women who waited until the third trimester to enter WIC. If the trimester of WIC enrollment for Texas is adjusted with use of an unweighted national sample, more women would have enrolled during the first two trimesters of pregnancy and 362 fewer babies with low birth weight would have been delivered by WIC enrollees during 1988. Efforts should be made to encourage early enrollment in WIC--and prenatal care--for women at high risk for delivering low birth weight infants.