胚胎染色体异常是导致流产、胎儿畸形等不良妊娠结局的重要原因之一，据统计，在早期自然流产中，约50% - 60%是由胚胎染色体异常引起的。
maternal age-related factors:
Maternal age over 35 years old: As women age, the quality of eggs gradually declines. For example, a woman at 35 years old has a lower chance of normal chromosomal development in embryos compared to a younger woman. The risk of embryo chromosomal abnormalities increases significantly with advancing maternal age. Older maternal age leads to increased chromosomal non - disjunction: The mechanism is related to the aging of egg cells, where the process of chromosome separation during meiosis is more likely to go wrong.
paternal factors:
Paternal age also has an impact: Although the effect is not as obvious as maternal age, older fathers also have an increased risk of sperm chromosome abnormalities. Studies have shown that paternal age over 40 years old is associated with a slightly higher probability of embryo chromosomal anomalies. Sperm DNA damage in older fathers: The DNA in sperm of older men may be more prone to damage, which can affect the normal chromosomal constitution of embryos.
environmental factors:
Exposure to radiation: If a woman is exposed to high - dose radiation, such as radiation from medical X - rays in excess of safe limits during early pregnancy, it can damage the chromosomes of the embryo. For example, being exposed to radiation in a nuclear accident or having repeated unnecessary medical X - ray examinations during pregnancy can increase the risk of embryo chromosomal abnormalities. Exposure to chemical toxins: Certain chemicals, like some pesticides (such as organophosphorus pesticides) and industrial chemicals (such as benzene - related substances), can cause embryo chromosomal damage. Long - term exposure to these chemical toxins in the work or living environment can raise the risk of embryo chromosomal abnormalities.