Objective: To investigate the epidemiological characteristics of cases with anotia and microtia in China.
Method: The birth defect monitoring program was undertaken by a hospital-based monitoring method in 443-588 hospitals from 30 provinces, cities and autonomous regions across China. Data including intrauterine death and stillbirth from 28 weeks of gestation to a period of 7 days postpartum were collected between 1988 and 1992.
Results: A total of 3,246,408 births was monitored from 1988 to 1992, in which 453 cases had anotia and microtia. The average incidence was 1.40 per 10,000 during the five-year period. The decreased tendency of incidence was noted during the period (chi 2 = 5.5588, P < 0.05). The incidence in the urban area was significantly higher than that in the rural area. There was no sex difference in the incidence of anotia and microtia. The incidence varied among 30 provinces with highest incidence in Xinjiang province (2.08 per 10,000 births) and lowest in the Inner Mongolia Autonomous Region (0.33 per 10,000 births). In cases with the defects of anotia and microtia, 60.4% were accompanied with other congenital malformations. The proportion of multiple malformations with microtia and anotia was significantly higher than that of isolated case (chi 2 = 36.9277, P < 0.01). The highest incidence of concurrent malformations was anophthalmia or microphthalmia (13.1%), followed by facial cleft (12.6%), neural tube defects (10.0%), limb reduction defects (9.6%) and polydactyly (5.4%). There were also 3.5% cardiac defects.
Conclusions: The prevalence of anotia and microtia varied among provinces across China. The high proportions of cases with anotia and microtia had multiple malformations. Therefore, careful examination of other malformations in patients with anotia and microtia is necessary.