Prevalence and trend of isolated and complicated congenital hydrocephalus and preventive effect of folic acid in northern China, 2005-2015.

Congenital hydrocephalus (CH) was a major birth defect of the central nervous system besides neural tube defects (NTDs). Few studies have focused on both the prevalence and trend of isolated and complicated CH in China. Data were drawn from a population-based birth defects surveillance program in five rural counties in northern China from 2005 to 2015. All livebirths and pregnancy terminations at any gestational age affected with CH were recorded. The prevalence and trend of isolated and complicated CH were examined. During the 11-year period, a total of 176,223 births and 357 CH cases were recorded, resulting in a prevalence rate of 20.3 CH cases per 10,000 births. Of the CH cases, 146 were isolated CH, resulting in a prevalence rate of 8.3 per 10,000 births. The pre-perinatal prevalence (<28 gestational weeks) was higher than the perinatal prevalence for both isolated and total CH. The prevalence rates of total and isolated CH showed a similar downward trend during the 11-year period. This downward trend was statistically significant after 2009 (p < 0.05), when a massive folic acid supplementation program was introduced. Although it decreased over time, the prevalence of CH remains high in this population which has a high prevalence of neural tube defects.