WIC prenatal participation and its relation to pregnancy outcomes in Missouri: a second look.

We studied the association of WIC prenatal supplementation with pregnancy outcome using Missouri WIC participants who delivered in 1982 linked with their offspring's birth/fetal death certificates. A 93 per cent match rate resulted in a final study population of 9,411 pregnancies. A control population of like number was acquired by matching on key demographic characteristics. The majority of the results generally confirm the results of a 1980 Missouri study; WIC participation was associated with decreases in low birthweight (7.8 vs 9.2 per cent), prematurity (9.7 vs 12.0 per cent) and inadequate prenatal care (30.5 vs 31.7 per cent), and an increase in mean gestational age (39.9 vs 39.6 weeks). Low birthweight rates were lower for infants of WIC participants in each of the risk categories reviewed. As noted in the 1980 study, duration of WIC of at least seven months was needed before improvements in birthweight outcomes measures were noted.