Of 7,984 live-born and stillborn infants and fetuses with congenital heart disease (HCC), 71.3% had isolated abnormalities, 13.5% had ACM, 13.1% had syndromes, and 2.0% had laterality defects. The rate of HCC in other population-based epidemiological studies ranged from 6.5% to 14.1% [30-33]. The current percentage (8.1%) of CMMs was clearly in this area. In contrast to the high prevalence of HCC, several cases took a small percentage compared to the percentage of WAB in other PGD categories, as seen in Table 3. Since oetic heterogeneity can make epidemiological analyses to identify risk factors for congenital anomalies difficult, it is important to classify cases using knowledge of embryological and pathogenic mechanisms  in order to make the case groups more homogeneous . Wellesley et al. The association models of the ICD-10 subcategory in WABs are presented in Table 4. Twenty-four cases (25%) had more than one disease in the same ICD-10 subcategory. „Congenital malformations of the circulatory system (Q20-Q28)”, „other congenital malformations of the digestive system (Q38-Q45)” and „congenital malformations and musculoskeletal deformities (Q65-Q79)” tended to occur simultaneously. The „cleft lip palate (Q35-Q37)” also tended to be associated with other birth defects. Forty-four different combination models at the ICD-10 subcategory of the organ system were detected for 96 MCAs. But the concomitant occurrence of diseases at a more detailed level of classification of the disease, namely the two-digit code according to Q (z.B Q21 for congenital malformations of cardiac sceptes) has been rarely observed. .