Incidence

During the period between 1981-1995, 267 children out of 132,723 newborns in Lódz (Poland) were born with cleft lip and/or palate. This made the mean prevalence of cleft over the 15 year period 2 per 1000. Isolated cleft palate occured most frequently (112), whereas cleft lip and palate, and especially cleft lip only were less frequent (104 and 51 respectively). Cleft palate occurred more often in girls than in boys (68:44), complete cleft lip and palate were more frequently seen in boys (66:38), whereas isolated cleft lip was observed to be equal in girls and in boys (26:25). Unilateral clefts occured at a significantly higher rate than bilateral ones (115:40), with boys being affected more often than girls (67:48). The cleft appeared rather on the left side than on the right (79:36).

The article draws the conclusion that the results of the research reported upon concerning the prevalence of cleft lip and/or palate, type and side of cleft and sex of the infants with clefts who were born in Lodz during the period 1981-1995 are consistent with world literature data.

This investigation describes the incidence and variability of the primary cleft condition in all Danish children born with cleft lip, cleft palate, or both. Denmark has had compulsory reporting of clefts since 1937, and with all procedures carried out in one centre by one surgeon, its reliable and nearly complete data lends itself favourably towards accurate analysis and interpretation.

Main findings;

• Of a total of 359,027 births in Denmark between 1976-1981, 678 were born with cleft lip, cleft palate, or both. This gives an incidence of 1.89 per 1000 live births (1:529). Year by year, this figure varied from 1.77 in 1978 (1:565) to 2.08 in 1977 (1:481).
• The distribution was 33.5% cleft lip only, 39.1% combined cleft lip and palate, and 27.4% cleft palate only.
• Both isolated cleft lip and combined cleft lip and palate were twice as frequent in males as in females.
• Left-sided cleft lips were twice as common as right-sided.
• 13% of unliateral cleft lips were complete clefts.
• 90% of unilateral cleft lip and palates were of a more severe type.
• 38% of bilateral cleft lip and palate patients had complete clefts of both sides, and 70% were complete on one or both sides.
• solated cleft palate was most common among females (60% of group). Females had more severe isolated palatal clefts than males.
• Fourteen of the cleft palate patients exhibited Pierre Robin syndrome, one exhibited Stickler’s syndrome, and one exhibited Apert syndrome.
• 7% of the cleft children had one affected parent, one affected sibling, or both. The figure was 14% for patients with a complete cleft lip, and 18.5% among those with a complete bilateral cleft lip and palate.
• 26 of the 602 patients included in the study had associated congenital defects (c.4.3%).
• The average parental age was found to be exactly the same as the general population.
• The overall trend in the sample indicates that birth weight and length of cleft babies do not differ from normal values. However, males with cleft palate revealed a significantly lower birth weight, and females with cleft palate were significantly shorter. The lower values may be explained by a lower gestation age for cleft palate children.

The study showed an increase in the incidence of clefting on the 1942 figure (1.5 per 1000). The factors alluded to as possibly responsible for the increased incidence include decreased neonatal mortality, environmental factors such as drugs, increased frequency of intermarriage, and childbirths in cleft patients because of better social acceptability and fertility. The incidence reported in this latest study parallels figures for the other Scandinavian countries as those the distribution (except for Finland).

The study comprised 502 patients, consisting of 291 males (58%) and 211 females (42%). It excluded submucous clefts, of which there were 23 cases in the period covered.

The overall incidence for cleft births over the 20-year period was 1.4 per 1000, or 1 in 711 live births. The variation ranged from 1 in 1013 in 1973, to 1 in 540 in 1987. While the incidence varies from year to year with quite dramatic swings, the incidence between the first and second 10-year period was not statistically significant (1:727 v 1:695).

53 infants (29 males, 24 females) presented with Pierre Robin sequence, and 92 with an associated syndrome.

25% of clefts affected the primary palate, while 45% affected the secondary palate. Bilateral cleft lip and palate affecting 11%, while the remaining 19% consisted of unilateral cleft lip and palate. Unilateral cleft lip and palate clefts are more prevalent on the left side (65%).

Females dominated isolated cleft palate accounting for 56% of the total. Male dominance was significant in both the cleft lip group (n=93 v 33) and the bilateral cleft lip and palate group (n=39 v 14).

The data presented in this study, including the dramatic year to year swings, was seen as consistent with previous studies reported in the UK literature.

Reports on the incidence of oral clefts in Germany over long periods do not exist because there has been no continuous system of registering malformations in place. However, since 1980 there has been such a system of registration in place in Magdeburg, which, with a population of 1.5 million, has had a yearly birth rate of approximately 8000.

Study of data for the region indicates that there has been a very high rate of oral clefts, mainly a cleft lip with or without a cleft palate, with a rate of 1.85 per 1000 births, ie. 1:540.

22% of all children with oral clefts had additional malformations. Heart defects accounted for the highest occurrence at about 10%.

A peak occurrence of neural tube defects from 1987 to 1989 resulting in increased incidence of clefts in 1988 and 1989 may be a causal factor in the high overall incidence reported.

The retrospective demographic epidemiological study reports on the incidence of cleft lip with or without cleft palate in the Czech Republic during the period 1961 to 2000.

Data from the Institute for the Care of Mother and Child in Prague (period 1961-1990) were used as well as data from the nationwide registration of birth defects of infants ensured by the Institute of Health Information and Statistics of the Czech Republic covering the period 1987-2000. Epidemiological analysis of the incidence of cleft lip with or without cleft palate diagnosed in the Czech Republic during 1961-2000, and mathematical statistical analysis of the prevalence of these defects by maternal age, the method of calculation of the 95% confidence limit of probability was used.

RESULTS: From a consecutive series of 5,589,888 births in the Czech Republic during 1961-2000, 1166 cases of cleft lip, 5052 cases of cleft lip and palate were diagnosed and 3970 cases of cleft palate. A total of 10,188 cases of facial clefts were recorded. The mean incidence of cleft lip during the investigation period was 2.09 per 10,000 liveborn infants, the incidence of cleft lip with/without cleft palate was 11.13 per 10,000 liveborn infants. The mean incidence of cleft palate during the investigation period was 7.10 per 10,000 liveborn infants and of facial clefts as a whole 18.23 per 10,000 liveborn infants.

CONCLUSION: The authors provided evidence that the frequency of facial clefts as a whole during the investigation period did not undergo significant changes as regards the trend of incidence. When evaluating maternal age as one of the risk factors for the development of facial clefts the investigation confirmed a greater risk in 15 year-old women and women older than 35 years, without exception.