Prevalence of congenital cryptorchidism in China: A nationwide population-based surveillance study, 2007-2021.

ABSTRACT

BACKGROUND: Despite cryptorchidism being a common genital abnormality in male newborns with significant prevalence variations globally, there is a notable scarcity of epidemiological data on this condition in China. OBJECTIVE: This study aimed to delineate the prevalence pattern of cryptorchidism in Chinese population over the past 15 years using nationwide surveillance data. MATERIALS AND METHODS: Data from the China National Population-based Birth Defects Surveillance System (2007-2021) were analyzed to calculate the prevalence rates of cryptorchidism, stratified by birth year, maternal age, maternal residence, and geographic region. Adjusted prevalence rate ratios were computed using Poisson regression, while trends in prevalence and average annual percent change (AAPC) were assessed using the joinpoint regression model. RESULTS: During the study period, a total of 1,833 cases of cryptorchidism were identified among 2,565,964 full-term male births, resulting in prevalence rates of 7.14, 5.60, and 1.54 per 10,000 births for overall, isolated, and associated cryptorchidism, respectively. The overall prevalence increased from 3.86 to 11.20 per 10,000 births, with an AAPC of 7.9% (95% confidence interval 5.5-11.0). Significant variations were observed across maternal age (< 20 years, 7.62/10,000; 20-24 years, 6.14/10,000; 25-29 years, 6.96/10,000; 30-34 years, 7.48/10,000; ≥35 years, 9.22/10,000), maternal residence (urban vs. rural, 10.99/10,000 vs. 2.86/10,000), and geographic region (eastern, 12.38/10,000; central, 2.36/10,000; western, 2.63/10,000). Approximately one-third of cryptorchidism cases were bilaterally, while two-thirds were unilateral. Commonly observed associated abnormalities included congenital hydrocele testis, as well as anomalies in the genital organs, circulatory system, and musculoskeletal system. CONCLUSION: Despite lower rates compared to other countries, the increasing trend in prevalence of cryptorchidism necessitates further investigation and intervention.