Introduction Spina bifida is a serious congenital anomaly associated with life-long disability. This study describes trends in the prevalence and survival of spina bifida, to 10 years, using data from a long-standing congenital anomaly register in Northern England.

Methods Cases of isolated spina bifida, delivered during 1985–2003, were identified from the population-based Northern Congenital Abnormality Survey (NorCAS). Survival status was determined from local to national records. Trends in prevalence and survival were examined by the Cochran-Armitage test and by Cox regression respectively.

Results 500 cases of spina bifida were identified during the study, including 196 (39%) live born cases. The total prevalence of spina bifida was 7.5 (95% CI 6.9 to 8.2) per 10 000 total births, while the live born prevalence was 3.0 (95% CI 2.6 to 3.4) per 10 000 live births. Total prevalence decreased over time from 9.6 (95% CI 8.4 to 11.0) per 10 000 total births in 1985–1990 to 5.8 (95% CI 4.8 to 6.9) per 10 000 total births in 1997–2003 (p<0.001). The proportion of terminations of pregnancy concurrently increased, from 40.2% (95% CI 34.0 to 46.6) in 1985–1990 to 72.4% (95% CI 64.5 to 79.3) in 1997–2003 (p<0.001). 10 year survival among traced live born cases (n=195) was 66.6% (95% CI 59.8 to 72.6), increasing with time from 60.2% (95% CI 51.1 to 68.0) in 1985-1990 to 83.3% (95% CI 64.5 to 92.7) in 1997–2003 (p=0.002).

Conclusions The prevalence of spina bifida has decreased over time while survival for live born cases has significantly increased. These data are important for counselling families when a spina bifida is detected and for health service planning.