Epidemiology of congenital anomalies in a population-based birth registry in Taiwan, 2002

Congenital anomalies are important medical and public health conditions. However, the occurrence rates of congenital anomalies and their risk factors are unknown in Taiwan. We used the medical-practitioner-reported birth registry in 2002 to determine the occurrence of individual congenital anomalies and their associated risk factors, such as maternal age, fetal sex, and plurality.

The birth registry was started in 2001 in Taiwan. We obtained the data for 2002 from the Department of Health, and translated the coding of congenital anomalies to International Classification of Diseases 9th revision-clinical modification (ICD-9-CM). The occurrence rates of individual congenital anomalies were calculated. The effects of maternal age, fetal sex, and plurality were calculated as odds ratios (ORs) by logistic regression analysis.

A total of 1775 infants were diagnosed as having congenital anomalies among 242,140 live and deceased newborn infants delivered in Taiwan in 2002.The occurrence rates of congenital anomalies of the nervous system, eyes and face, cardiovascular, digestive, urogenital, musculoskeletal and respiratory systems, and chromosomes were 0.67 per thousand, 1.86 per thousand, 1.47 per thousand, 0.62 per thousand, 0.71 per thousand, 2.05 per thousand, 0.07 per thousand and 0.79 per thousand, respectively. Sex chromosomal anomalies, Down syndrome, and trisomy 18 were associated with maternal age of > or = 35 years (OR, 15.9, 4.6, and 2.3, respectively). Such elevation was even more prominent for maternal age > or = 40 years (OR, 35.5, 22.2, and 11.62, respectively). A milder and borderline significant maternal age (> or = 40 years) effect was seen with cleft lip, with or without cleft palate (OR, 2.1). Female births had more cleft palates (OR, 1.6). There was no relationship between plurality and anomalies.

The occurrence rates for individual congenital anomalies in Taiwan were reported. Older maternal age was a risk factor for the occurrence of chromosomal and orofacial anomalies. More active prenatal screening and further investigation of causal factors of congenital anomalies are of major importance.