Answer to Question 1
1,2,4,5
Rationale 1: The use of saunas or hot tubs is associated with maternal hyperthermia, and can cause CNS defects and failure of neural tube closure.
Rationale 2: The use of drugs can have teratogenic effects.
Rationale 3: The quality of the sperm or ovum will affect embryonic development but not necessarily affect the intrauterine environment.
Rationale 4: Maternal nutrition, if deficient, can cause damage to the fetus.
Rationale 5: Vitamins and folic acid taken prior to and during the pregnancy can have beneficial effects.
Answer to Question 2
1
Explanation: 1. By the end of the fourth week, embryonic blood is circulating between the embryo and the chorionic villi.