Vigilancia epidemiológica de anomalías congénitas en España: Análisis de los datos del ECEMC en el período 1980-2006

Abstract

This chapter summarizes the main results of the current epidemiological surveillance of congenital anomalies performed in the Spanish Collaborative Study of Congenital Malformations (ECEMC). This is a research programme developed as a hospital-based case-control study and surveillance system, aimed at investigating the characteristics and causes of congenital defects. It started in 1976, with a common methodology for all the participants in the programme. According to the most recent data, it covers 22.96% of births in Spain. It has been found that the general tendency of the neonatal frequency of congenital defects in Spain is decreasing since the passing, in 1985, of the law allowing voluntary termination of pregnancy (TOP) after the detection of fetal anomalies. The frequency has fallen from the base frequency registered in 1980-1985 (2.22%) up to 1.16% in the year 2006. This general tendency has also been proven for most of the defects under systematic surveillance in the ECEMC. The most noticeable decrease has been observed for the global frequency of Down syndrome, and this decrease is even more pronounced for the oldest maternal ages, as a result of the impact of TOPs. In the analyses by Autonomous Regions (look at the map in Figure 1 to see their location), there was only a statistically significant increase of the global frequency, in Extremadura, that can be attributable to the improvements in the neonatal and obstetrical care in this region, not being necessary to move deliveries at risk to other Autonomous Regions. Regarding the frequency of specific defects, there have been increases in the frequency of esophageal atresia/stenosis in Castilla-La Mancha, anal-rectal atresia/stenosis in Tenerife (Islas Canarias), gastroschisis also in Tenerife, and hypospadias in Castilla y León. For the first two defects, after excluding cases with syndromes with multiple congenital anomalies, they lost statistical significance. For gastroschisis in Tenerife, there were some risk factors among the cases (young maternal age, change in paternity of the different infants of the mother) that could account for the cluster, although it will be closely followed up. For hypospadias, there has not been found any common denominator in the cases that could be considered as the cause of the cluster in Castilla y León, that will also be closely monitored. In conclusion, the ECEMC system of epidemiological surveillance has demonstrated being effective in determining the birth frequency of congenital defects in Spain, its secular trend and geographical distribution, as well as for detecting several increases in the frequency of some congenital defects, leading to a close monitoring of the clusters, which is important for determining their causes and for the prevention of congenital defects, apart from their usefulness in the planning of health and social resources.