Final answer:
Congenital diseases and disorders are most likely to occur during critical periods of fetal development, when organs are most susceptible to teratogenic effects. Rubella infection during pregnancy can lead to congenital rubella syndrome with severe complications. Maternal age and placental insufficiency are also factors that increase the risk of congenital diseases and disorders in the fetus.
Step-by-step explanation:
Congenital diseases and disorders can occur throughout fetal development, but they are most likely to occur during critical periods of organ development. Each organ has a specific sensitive period during which it is most susceptible to teratogenic effects. For example, exposure to alcohol during day 19 or 20 of gestation can lead to significant facial abnormalities in the offspring.
Rubella infection during pregnancy can cause congenital rubella syndrome, which results in stillbirth, spontaneous abortion, or birth defects. The risk is highest if the infection occurs before 11 weeks of pregnancy.
The incidence of having a fetus with chromosomal abnormalities, such as trisomy 21, increases with maternal age. Placental insufficiency can also lead to intrauterine growth restriction and low birth weight.