Prevalence of Neural Tube Defects and the Impact of Prenatal Diagnosis in Three Districts of Beijing, China

Background The objectives of this study were to explore the prevalence of neural tube defects (NTDs) in three districts of Beijing, and to evaluate the impact of prenatal diagnosis on the prevalence. Methods Data were collected between 2006 and 2012 from the Beijing Birth Defects Surveillance System. P-13 and P-28 represent the prevalence of NTDs diagnosed from 13 weeks and 28 weeks of gestation, respectively, to 7 days after delivery. Populations were classified as household (permanent) and non-household (non-permanent) because differences exist in access to health care, education, and income, among others. Results The P-13 of NTDs was 11.7 per 10 000 births in the three districts, which declined from 2006-12. In addition, the prevalence of NTDs in the non-household population was 1.7-fold higher than that among the household population. The P-13 of anencephaly, spina bifida, and encephalocele were 5.3, 4.9, 1.6, respectively, per 10 000 births. The P-28 of NTDs only represented 29.1% of P-13, and this proportion decreased over the 7-year period. Conclusions The prevalence of NTDs remains high in the three districts of Beijing, and the rate was higher in the non-household than household population. The prevalence of birth defects would be under estimated by almost 70 per cent if the report time was set on 28 weeks' gestation or later compared with report time on 13 weeks of gestation. It is better to set the report time earlier in birth defect surveillance in contemporary China.