Purpose: It is difficult to obtain reliable figures on incidence of anorectal malformations (ARM) from literature. The aim of the present study was to reveal the real incidence of these defects in a given area. Material and methods: Between 1992 and 1997, 86 children with ARM were treated at the departments of paediatric surgery in Łódz. Parents of 30 (34.9%) children treated within the analysed period lived in the Łódz province. The real incidence of ARM in this area was calculated and birth parameters of children with ARM were compared with corresponding parameters of newborns born alive in Łódz. Results: The studied incidence ranged from 1 in 1446 to 1 in 3035 in consecutive years and the average was 1 in 2295. Mean duration of pregnancy in children with low type ARM was 39.4 weeks and in children with high type ARM - 38.8 weeks. Mean birth body weight of children with low defects was 3030 g, and of neonates with high defects - 3185 g. Apgar score was respectively 8.7 and 8.8. There was also no significant difference in examined parameters (p > 0.05) between ARM children and the population of born alive newborns of Łódz area (respectively 38.9; 3297; 8.9). Conclusions: Anorectal malformations are among the common congenital anomalies in children. In the analysed group of children with ARM duration of pregnancy, birth weight and Apgar score were similar to these observed in the whole population of newborns born alive in Łódz province.

Keywords: Łódz province, newborns birth parameters, Incidence, Anorectal malformations