There are about 50 reasons for congenital developmental defects of upper limbs in a child.
A child is born with a developmental defect if the woman was exposed to a harmful factor in the 4–7 week period of pregnancy.
All the reasons can be divided into 3 groups:
External factors. For example, taking drugs, illness of the mother during pregnancy (for example, acute respiratory illness, flu, rubeola), chemotherapy, etc. These factors could alter the normal course of fetal formation.
Endogenous factors. Genetic predisposition and hereditary transmission of a trait. In some cases, the anomaly may be transmitted by heredity.
Unestablished factors – about 50% of children with underdevelopment are born with an unidentified cause of the anomaly.