What are critical periods of development? What critical periods of prenatal development of a person are known to you?

Critical periods are those periods of ontogenesis, during which the developing organism is most sensitive to certain influences. As a rule, the critical periods of intrauterine development are confined to those stages of the development of the body when the processes of formation and active development of the main organs and systems occur. Each organ has its own critical period, although the interval between the 15th and 60th days of pregnancy is considered critical for many organs. The heart is formed between the 3rd and 4th weeks, while the external genitalia are most sensitive to influences between the 8th and 9th weeks. The nervous system and skeleton, starting from the 3rd week after conception and throughout the duration of pregnancy, are constantly sensitive to harmful influences.