Screening for congenital neural tube defects in a high-risk area: an epidemiological perspective.

Abstract

SUMMARY Data from the Glasgow Register of Congenital Malformations were used to investigate the extent of the recent decline in the prevalence of anencephaly and spina bifida, and the contribution of antenatal screening to it. Over the period inclusive, 303 pregnancies with an anencephalic foetus were diagnosed, representing an "adjusted" prevalence of 1-9 per 1000 total births, of which 179 (59%) were terminated following antenatal screening. There were 364 pregnancies with a spina bifida foetus representing an "adjusted" prevalence of 2-3 per 1000 total births, of which 84 (23%) were terminated. Over the study period, the "adjusted" prevalence of anencephaly fell by 50% while the birth prevalence fell by 89%; the "adjusted" prevalence of spina bifida fell by 38% while the birth prevalence fell by 76%. It was concluded that although the birth prevalence of both defects (particularly anencephaly) would have declined substantially in the absence of screening, the West of Scotland programme should continue.

Use of local neural tube defect registers to interpret national trends.

“…66% of the true number of local cases. e (at birth or Enhancing the local register cases with data ined over the from OPCS suggests the local register is then id elsewhere 990 o complete, and that the true number of :rvation),14 15 NTDs over the period (with 95% confidence ths has fallen interval) is 557 (550-564).…”

Lead levels in domestic water supplies and neural tube defects in Glasgow

“…The register has been in existence long enough to enable secular trends to be identified. Stone et al showed that in Glasgow over the period 1974–85, the pregnancy prevalence of anencephaly fell by 50% (from 2.2 to 1.1/1000), whereas the birth prevalence fell by 89% (from 1.9 to 0.2/1000); the pregnancy prevalence of spina bifida fell by 38% (from 3.4 to 2.1/1000), whereas the birth prevalence fell by 76% (from 3.4 to 0.8/1000) 12. The pregnancy prevalence rate produces a number equivalent to the number of affected births that would have occurred had there been no antenatal screening.…”

The glasgow register of congenital anomalies 1972–88: A critical review

“…For example, while the prevalence of all defects has remained static for several years, the prevalence of neural tube defects has declined steadily throughout the 1970s and 1980s (Stone et at., 1988). This decline has been mirrored by hydrocephalus, suggesting a possible common aetiology.…”

“…They include neural-tube defects (Stone et al, 1988), microcephalus (Dolk et al, 1986), hydrocephalus, congenital heart disease, facial cleft s (Womersley and Stone, 1987) and metabolic disorders. Data on this last group have not previously been reported by the Glasgow Register.…”

“…Screening for neural tube defects by serum-alphafetalprotein assay is the obvious example (Stone et al, 1988), but Down's Syndrome, PKU and Congenital Rubella Syndrome are other potential subjects for investigation.…”