Neural Tube Defects in China

Studies in China continue this section. By 1986–7 it had been discovered that certain northern areas had far greater NTD frequencies than southern ones, differences at least as great as those from country to country in Europe—a nonoverlapping spread of 3–10 in the north and 0.7–1.3 in the south, with the Zangtze River roughly the dividing line. Differences confirmed later by findings in 1992–4 in unnamed regions in the north and south of 4.83 and 0.71 respectively, with rural levels higher than urban ones in both regions (Pei et al. 2003).