Question
At what stage of pregnancy can fetal malformations and mental retardation be detected?
Answer
Fetal malformations primarily occur in the early stages of early pregnancy, from the 3rd to the 8th week, which is a crucial period for organ formation. External influences during this time may lead to malformations. At this stage, the fetus is very sensitive to external factors, and any interference may cause severe malformations. After the 9th week, except for the brain, external genitalia, teeth, and upper jaw, which are still developing, the sensitivity of other organs to external teratogenic factors has decreased. If affected at this time, it may lead to mental retardation or malformations in external genitalia and organ alliance dysfunction.