Impact of Prenatal Diagnosis on the Birth Prevalence of NTDs

Objective:
To determine the impact of prenatal diagnosis on the birth prevalence of neural tube defects (NTDs) in Atlanta during 1990 through 1991.
Methods. Live-born and stillborn infants with NTDs who were at least 20 weeks’ gestation were ascertained by the Metropolitan Atlanta Congenital Defects Program (MACDP), a population-based birth defects registry. Prenatally diagnosed NTh-affected pregnancies were ascertamed from the four perinatal centers and the three genetic laboratories operating in Atlanta during 1990 through 1991. Fetal death certificates were also reviewed for potential cases.

Results:
During 1990 through 1991, MACDP ascertamed 59 NTh cases, for a birth prevalence of 0.77/1000 live births. During this period, an additional 28 NTDaffected pregnancies were detected prenatally and terminated before 20 weeks’ gestation. The adjusted NTh rate
during 1990 through 1991, which includes prenatally diagnosed cases, was 1.13/1000 live births.

Conclusions:
Prenatal diagnosis is making a substantial impact on the birth prevalence of NTDs in Atlanta.
However, since NTD rates in Atlanta were 2 to 2.5 per 1000 live births in 1970, prenatal diagnosis and termination of pregnancy does not completely account for the declining rate of NTDs.

Impact of Prenatal Diagnosis on the Birth Prevalence of Neural Tube Defects, Atlanta, 1990-4991. Helen E. Roberts et al. Pediatrics 1995;96:880-883;

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