Survival of Texas infants born with trisomies 21, 18, and 13.

Trisomies 21, 18, and 13 are the three most common trisomies among infants who survive to 20 weeks gestation or more. Overall information about birth prevalence, natural history, and mortality for all three trisomies is well defined, but information about ethnic-specific rates is limited. Only a few studies have examined mortality rates of trisomies 18 and 13 because so few cases are liveborn and most have very short life spans.