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

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

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

RESULTS: 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.

CONCLUSIONS: 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.