The main causes of the 1% chromosomal aberration rate include maternal age, genetic factors in both spouses, physical or chemical influences, and viral infections. The causes of 1% chromosome aberration rate mainly include: 1. age of pregnant women: older pregnant women are prone to chromosomal aberrations during childbirth. 2. Hereditary factors of both husband and wife: chromosomal aberrations of both husband and wife will be passed on to the offspring, resulting in the possibility of chromosomal aberrations in the offspring. 3. Physical or chemical influences: physical factors, such as X-ray radiation and ionizing radiation, chemical factors, such as teratogenic drugs, pesticides, poisons, chemotherapeutic drugs, etc. can lead to chromosomal aberrations. 4. Viral infections: Pre-pregnancy TORCH test can be conducted to detect toxoplasmosis, rubella virus, cytomegalovirus and other infections, which may cause chromosomal aberrations in the fetus.