Epidemiologic characteristics and time trend in the prevalence of anotia and microtia in China

Background: Previous studies have shown an inconsistent time trend on the prevalence of anotia and microtia. Little has been reported on the epidemiologic characteristics of anotia and microtia in the Chinese population.

Methods: Data from 1996-2007 were obtained from the Chinese Birth Defects Monitoring Network in China. Birth prevalence of anotia and microtia were assessed according to demographic characteristics and annual time trend. Poisson regression was used to calculate crude and adjusted prevalence ratios (APRs) and 95% confidence intervals (CIs) for selected demographic characteristics and subgroups of anotia and microtia.

Results: A total of 1933 cases with anotia/microtia were identified among 6,308,594 live births, stillbirths, and terminations of pregnancy, yielding a rate of 3.06 per 10,000 births. Isolated anotia/microtia had a prevalence of 2.25 per 10,000 births, whereas among nonisolated cases, the prevalence was 0.81 per 10,000 births. The prevalence rates of anotia/microtia increased significantly during 1996-2007 (p < 0.05). Birth prevalence of isolated anotia/microtia was significantly higher among western births (APR, 1.24; 95% CI, 1.10-1.40), mothers residing in urban areas (APR, 1.29; 95% CI, 1.15-1.46), mothers more than 35 years of age (APR, 1.26; 95% CI, 1.01-1.57), and males (APR, 1.38; 95% CI, 1.24-1.53). No significant associations were observed between nonisolated anotia/microtia and geographic areas, maternal residence, and infant sex (except for maternal age).

Conclusion: An increasing trend of the birth prevalence of anotia and microtia is observed in China. Higher prevalence risk of isolated anotia and microtia is found among western births, mothers residing in urban areas, older mothers, and males.