The Hungarian Case-Control Surveillance of Congenital Abnormalities (HCCSCA)
Cases with CAs in the HCAR were enrolled to the HCCSCA if they met all the following selection criteria: (a) Reported to the HCAR within 3 months after birth or elective termination of pregnancy, (b) Did not have any of three mild CAs (dislocation of the hip, congenital inguinal hernia and large haemangioma) and (c) Did not have CA-syndromes caused by gene mutations or chromosomal aberrations with preconceptional origin.
Controls were defined as new-born infants without CAs and they were matched to cases according to sex, birth week, and district of parents’ residence. These controls were selected from the National Birth Registry of the Central Statistical Office based on case lists for each quarter of the years from the HCCSCA. In general, 2 controls were selected for each malformed new-born. If controls were twins, only one of them was randomly selected for the HCCSCA. In addition, if selected controls had any CA, these infants were excluded from the group of controls.
The HCCSCA was established in 1980. The collection of data was changed in 1997, slightly modifying the structure of the HCCSCA also. All data collected in the HCCSCA between 1980 and 2009 were unified into a validated single database that is now open for examination. This dataset of the HCCSCA is evaluated in this paper.