[Birth defects incidence in children from single and twin pregnancies in the Czech Republic--current data].

AIM OF STUDY: An analysis of occurrence of birth defects in children from single and twin pregnancies in the Czech Republic in 1994-2007. An assessment of total numbers and relative incidences of birth defects in births according to Tenth Revision of International Classification of Diseases (ICD-10).

TYPE OF STUDY: Retrospective epidemiological analysis of birth defects incidences from the Czech National Birth Defects Register database.

MATERIAL AND METHODS: Data from the National Birth Defects Register (Institute for Health Information and Statistics) in the Czech Republic in the 1994-2007 period were used. In this study, particular diagnoses--as they were registered in the National Register--were analyzed. Birth defects were analyzed separetely for children from single and twin pregnancies. The diagoses in study were divided into following eleven birth defects groups according to ICD-10 classification: (Q00-Q07) nervous system, (Q10-Q18) eye, ear, face and neck, (Q20-Q28) circulatory system, (Q30-Q34) respiratory system, (Q35-Q37) cleft lip and cleft palate, (Q38-Q45) digestive system, (Q50-Q56) genital organs, (Q60-Q64) urinary system, (Q65-Q79) musculoskeletal system, (Q80-Q89) other defects and (Q90-Q99) chromosomal abnormalities, not elsewhere classified. Total numbers and mean incidences of birth defects separetely for children from single and twin pregnancies were assessed for all these 11 groups.

RESULTS: In the Czech Republic during 1994-2007 period, totally 1,312,930 children were born (live births and stillbirts) from single pregnancies, whereas 42,448 from twin pregnancies. A twin rate (out of a total number of births) increased from 2.33% in 1997 to 4.17% in 2004. An overall incidence of diagnosed birth defects was 436.03 per 10,000 live births in singletons and 598.38 in twins. Birth defects incidence (per 10,000 livebirths)in singletons and twins in each of 11 birth defects groups under the study was during the 1994-2007 period as follows: (Q00-Q07) nervous system 9.45 in sigletons and 17.20 in twins, (Q10-Q18) eye, ear, face and neck 21.69 in singletons, and 18.38 in twins, (Q20-Q28) circulatory system 154.16 in singletons and 272.57 in twins, (Q30-Q34) respiratory system 4.92 in singletons and 5.65 in twins, (Q35-Q37) cleft lip and cleft palate 16.79 in singletons and 20.02 in twins, (Q38-Q45) digestive system 18.97 in singletons and 28.74 in twins, (Q50-Q56) genital organs 52.07 in singletons and 56.30 in twins, (Q60-Q64) urinary system 34.21 in singletons and 56.78 in twins, (Q65-Q79) musculoskeletal system 87.49 in singletons and 90.93 in twins, (Q80-Q89) other defects 26.06 in singletons and 22.14 in twins and (Q90-Q99) chromosomal abnormalities 10.20 in singletons and 9.66 in twins.

CONCLUSIONS: The study gives differentiated results of incidences of selected types of birth defects in births according to pregnancy multiplicity. A statistically significant difference (p<0.001) in total birth defects incidence in twins compared to singletons was confirmed. Same statistical significance (p<0.001) was also found (twins compared to singletons) in following birth defects or their groups: (Q00-Q07) nervous system, Q20-Q28) circulatory system, (Q38-Q45) digestive system, (Q60-Q64) urinary system, congenital hydrocephalus, some congenital heart defects, cleft lip and/or palateoesophageal atresia, anorectal malformation, hypospadia, congenital hydronefrosis, polydactyly and syndactyly. A statistically significant difference (p<0.01) was found in spina bifida, hypoplastic left heart syndrome, duodenal atresia/stenosis, diaphragmatic hernia and Down syndrome.