Prevalence of neural tube defects in the province of Quebec, 1992.

A retrospective study of neural tube defects (NTDs) was carried out among elective terminations of pregnancies, stillbirths and live births to women residing in two regions of Quebec, in 1992. Primary data sources included the hospital administrative data system MEDECHO, stillborn and infant death certificates, and the list of patients seen at three spina bifida clinics. Hospital records were reviewed. A total of 30 NTD cases were identified. The prevalence rate was 1.41 per 1,000, indicating a three-fold reduction in frequency during the last three decades. All 17 cranial defects but only 5 of 13 spinal defects were diagnosed during pregnancy. Elective terminations were performed at an average gestation of 18 weeks (range 11 to 21 weeks). The MEDECHO file allows a complete identification of NTD cases, but diagnostic categories are not very specific and coding errors are present.