Epidemiologic factors causing cleft lip and palate and their regularities of occurrence in Estonia

To study epidemiological factors causing development of cleft lip and palate and their occurrence regularities.

This study included 583 cleft lip and palate patients and the information for statistical analyses was gathered from Tartu University Hospital.

19% of the patients had a cleft lip (CL), 39% of the patients had a cleft palate (CP), and 42 % of the patients had a cleft lip and palate (CLP). The ratio for different cleft types CL: CLP: CP was 1:2:2. In unilateral CLP and CL cases, the left side was affected 2.2 times more frequently than the right side. Boys had a CLP nearly 2.1 times more often than girls. CP was more common for girls (60%) than for boys (40%). 30% of children had multiple malformations. 2.6% of children with clefts were born premature, half of which had accompanying developmental anomalies. The average birth weight for cleft child was ~3400 grams. 6.8% of children with clefts had a birth weight below 2.5 kg. In case of children with clefts, the mother's age exceeded 30 years in 1/4 of cases and father's age in 1/3 of cases. Both parents were older than 30 years in 66% of the cases. 1/5 of both parents were older than 30 years. 1/3 of mothers of children with clefts had suffered psychological stress, 1/5 of mothers had done hard physical work. 1/5 of mothers had an exposure to teratogenic toxic substances. 15% of them received medications during the first trimester of pregnancy. 15% of mothers had experienced hormonal disorders.

As a result of the study we found a high occurrence rate of CP (CL: CLP: CP--1:2:2), which is similar to the studies conducted in Finland and Sweden. The reasons for this ratio need further research.