Cleft lip, also known as hare lip, and cleft palate, also known as lupus, are common congenital malformations of the oral and maxillofacial region. Cleft lip and cleft palate can occur separately or simultaneously. According to statistics: the incidence of cleft lip and palate in newborns in China is about 1:1000, and the occurrence of cleft lip and palate is more in males than females, and more on the left than on the right.
Etiology of cleft lip and cleft palate
In a normal fetus, after the fifth week, some embryonic protrusions begin to gradually fuse with each other to form a face, and if they fail to develop normally and fuse with each other, congenital cleft lip and palate malformations occur. Cleft lip occurs when the globus pallidus at the lower end of the middle nasal eminence fails to fuse with the maxillary eminence at week 7, while cleft palate occurs when the palatal eminence and nasal septum fail to fuse with each other at week 10.
As for the causes of cleft lip and cleft palate due to failure to fuse, although not fully understood, they are related to the following factors.
(1) Genetic factors.
Cleft lip and palate is a polygenic genetic disease with a normal incidence of 0.10% to 0.17%, but with a father with cleft lip, the prevalence of the offspring is about 3%, and if the mother has cleft lip, the chance of inheriting it to the child is as high as 14%.
(2) Nutritional deficiencies.
Vomiting, anorexia and partial eating during a woman’s pregnancy can affect nutritional intake, causing deficiencies in vitamins (such as vitamins A, E, B2, B6, C, D), folic acid, and minerals such as calcium, phosphorus, and iron.
(3) Viral infections.
In the early stages of pregnancy (within 2 months), viral infections such as viral colds or rubella may be the cause of cleft lip in infants.
(4) Drug factors.
The drugs that have been identified to cause cleft lip and palate deformities include adrenocorticotropic hormones, antiepileptic drugs, anti-malignant drugs, anti-allergy drugs, etc.
(5) Endocrine disorders.
In the early stage of pregnancy (within 8 weeks), if the pregnant woman is emotionally stressed, or for physiological or mental reasons, the secretion of adrenocorticotropic hormone in the body increases, which leads to malformation of the embryo.
(6) Radiation.
If exposed to radiation in early pregnancy, it may cause mutation of embryonic cells resulting in fetal cleft lip and palate.
(7) Smoking and alcohol abuse.
Pregnant women who smoke and drink alcohol can also cause cleft lip and palate in the baby.
(8) Parental age factor.
There is a correlation between the incidence of cleft lip and palate and the age of the parents at childbirth, with a higher risk of cleft lip and palate occurrence in those with a childbirth age of 35 years or older.