Vigilancia Epidemiológica de Anomalías Congénitas en España durante el período 1980–2001

Abstract

We analysed the data gathered by the ECEMC Program since 1980 till 2001, in order to study the frequency of congenital defects (CD) among more than 1.800.000 newborn infants in Spain, its evolution over the time, and the birth prevalence of CD in the different Spanish Autonomic Regions (AR). The analysis also included the birth prevalence of series of selected CD (because of their relatively high frequency, or the mortality/morbidity they bear), their time distribution, their combined distribution by time and AR, and the impact of the voluntary interruption of gestation (VIG) after prenatal detection of anomalies in the fetus. We analysed the data in 3 periods: 1980–1985, which is the period preceding the pass in Spain of the law allowing VIGs before the 22 weeks of gestation due to congenital defects in the fetus. 1986–2000, which is the period following the pass of the mentioned law, and 2001, which is the year we are analysing. The prevalence figures in the first period can be considered as de baseline frequencies in our population, since the VIG was not permitted by law. We have observed statistically significant decrease of the global frequency of CD, which was 1.14% in 2001, being 2.22% in the base period. The main cause of this decrease frequency, are VIGs after prenatal detection of CD in the fetus. We have also analysed the data gathered on VIGs due to CD, but the results are not substantially modified, since not all the articipating hospitals can report data on VIGs. Regarding the global prevalence observed in the different AR, we detected significantly decreases in 11 of the 17 AR. Only Extremadura experiment a significant increase trend, which is attributable to the improvements in the neonatal care units permitting to take care of infants that in the past were born in other Regions after prenatal diagnosis of CD after the 22 weeks of gestations. Among the 16 selected CD, 12 show a statistically significant decreasing trend along the time. These are: anencephaly, spina bifida, encephalocele, hydrocephaly, anophthalmia/ microphthalmia, cleft palate, cleft lip, diaphragmatic hernia, hypospadias, omphalocele, limb reduction defects, and Down syndrome. Some others defects shown a tendency to diminish, but without reach the statistical significance. It is important to comment that hypospadias, that have had a stable frequency along the time until 1995, showed an important decreasing frequency in 1996, and since that moment have been stable but in low levels of frequency. A specific study is being conducted nowadays in order to figure out the cause of such change in their prevalence. Six defects (anencephaly, spina bifida, cleft palate, cleft lip, limb reduction defects, and Down syndrome), show a generalized tendency to diminish their frequency at birth over the time in the different AR, although in some of them the tendency is not statistically significant yet. In conclusion, it is clear from our data, the great impact of VIGs on the birth prevalence of CD. However, we could consider that some other factors, such as the primary prevention of neural tube defects and other anomalies with periconceptional intake of folic acid may also affect to the decrease birth frequencies. Other measures, as the better planning and care of pregnancies, may also act as a primary prevention. However, at present times, it is near impossible to analyse their individual contribution.