Frequency of congenital anomalies in Spain: Epidemiological surveillance in the ECEMC during the period 1980-2007

Resultados de Vigilancia Epidemiológica de los defectos congénitos sobre los datos del ECEMCThe ECEMC (Spanish Collaborative Study of Congenital Malformations) is a research programme, based on a hospital-based, case-control registry of newborn infants in Spain. It was created in 1976 by María Luisa Martínez-Frías and since then it has surveyed a total population of more than 2.5 million births, and studied more than 38,000 infants with congenital anomalies. The coverage of the registry is 21.18% of total births in Spain. The global frequency of infants with congenital defects in Spain has significantly decreased along the time since the passing of the law (year 1985) permitting termination of pregnancy (ToP) after the diagnosis of fetal defects. Thus, the birth frequency has dropped off from 2.22% in the basal period, to 1.43% in 1986-2006, and 1.17% in 2007. This decrease has also been statistically significant in most of the Spanish Autonomic Regions (see Fig. 1), and in many participating hospitals, and affects most of the defects that are routinely under surveillance. These decreases are considered mainly attributable to the impact of ToP. The only Autonomic Region in which an increase of the frequency was observed, was Extremadura, in which the health care has improved considerably in obstetrics and neonatology, allowing the attention of more complicated pregnancies and infants with serious congenital defects, which in the past were transferred to other regions. With respect to the study of a group of 33 defects, which were selected due to their relatively high base frequency or to the morbidity/mortality that they bear, only the heart/vessels defects and unilateral renal agenesis have increased with time. This must be the result of enhancing possibilities for their diagnosis. From the temporal-spatial analyses, there have been increases in the frequency of anophthalmia/microphthalmia in Baleares, diaphragmatic hernia in Tenerife (Islas Canarias), and omphalocele also in Tenerife. The first one was caused by the birth of just one case in 2007, and no causal agent could be specifically linked to the Balearic Islands. Regarding diaphragmatic hernia in Tenerife, after excluding one case with Brachmann-de Lange syndrome, the increase lost its statistical significance, and apparently there was not any common denominator among the other cases registered. With respect to the increase of omphalocele in Tenerife, this was due to the birth of 2 cases in 2007, without any known common characteristic from which a causal relationship could be inferred. Given that there were 2 defects the frequency of which has increased in Tenerife, it could be thought that they could be somehow related. However, omphalocele and diagphragmatic hernia are etiologically and pathogenetically different, so these findings must rather be independent. As in previous years, the ECEMC system of epidemiological surveillance has demonstrated being the only system in Spain to determine the birth frequency of congenital defects in this country, its evolution along the time, and their comparative geographical as well as temporal-spatial distribution. This is the base for causal studies, for planning of healthcare and social resources, and for designing preventive campaigns.N