Abstract
BACKGROUND: Periconceptional folic acid supplementation has progressively reduced the prevalence of neural tube defects (NTDs) in rural Northern China, which had a high baseline. Long-term epidemiological trends have not been comprehensively assessed in urban China with a lower baseline. METHODS: Data from a hospital-based birth-defect surveillance system in Haidian District between 2013 and 2022 were used. The prevalence of NTDs by different characteristics was analysed. χ(2), Pearson's tests and Joinpoint regression analyses were used to compare the prevalence of NTDs by year and explore trends. RESULTS: 363 732 births and 258 NTDs were recorded in Beijing's Haidian District from 2013 to 2022. NTD prevalence did not change significantly: it decreased in the first 4 years, then increased and subsequently hovered around 8.14/10 000. Stalling of NTD prevention is superimposed on changing maternal socio-demographics, including increasing education and self-reported regular use of folic acid in NTD-affected pregnancies. Maternal age of NTD-affected pregnancies also increased markedly from 2013 to 2022. To test which factors might alter NTD risk, we compared NTD-affected pregnancies with those affected by non-NTD congenital malformations. Compared with non-NTD malformations, advanced maternal age and multiple birth are independent risk factors for NTDs (adjusted OR: 1.776 and 2.513, respectively). Multiparity and regular folic acid use are protective factors (adjusted OR: 0.040 and 0.556). CONCLUSIONS: The accessibility of maternal folic acid in urban China needs to be evaluated, and it is necessary to investigate biological differences which may render some NTDs folic acid resistant. Meanwhile, the implementation of mandatory fortification of foods with folic acid is imperative.