The hormone responsible for maturation of mammary gland tissue is:

Choice A reason: Vascular volume increases during pregnancy to meet the increased oxygen and nutrient demands of the fetus, not to compensate for decreased renal plasma flow. In fact, renal plasma flow increases by 50% to 80% during pregnancy to facilitate the excretion of metabolic wastes.

Choice B reason: Vascular volume increases during pregnancy to ensure adequate blood supply to the uterus and other organs, not to prevent maternal and fetal dehydration. Dehydration can occur due to vomiting, diarrhea, or inadequate fluid intake, and it can be prevented by drinking enough fluids and replacing electrolytes.

Choice C reason: Vascular volume increases during pregnancy to provide adequate perfusion of the placenta, which is the main organ of gas exchange and nutrient delivery for the fetus. The placenta receives about 10% of the maternal cardiac output at term.

Choice D reason: Vascular volume increases during pregnancy to support the growth and development of the fetus and the maternal tissues, not to eliminate metabolic wastes of the mother. Metabolic wastes are eliminated by the kidneys, lungs, skin, and gastrointestinal tract.

Choice A reason: Partial abruptio placentae is not the correct answer, as it does not always require delivery by cesarean section. Partial abruptio placentae is a condition where the placenta partially separates from the uterine wall before the baby is born. This can cause bleeding, pain, and fetal distress. Depending on the severity of the condition, the gestational age, and the fetal status, the delivery may be vaginal or cesarean.

Choice B reason: Ectopic pregnancy is not the correct answer, as it does not require delivery by cesarean section. Ectopic pregnancy is a condition where the fertilized egg implants outside the uterus, usually in the fallopian tube. This can cause bleeding, pain, and rupture of the tube. Ectopic pregnancy is not viable and needs to be removed surgically or treated with medication. It cannot result in a live birth².

Choice C reason: Eclampsia is not the correct answer, as it does not always require delivery by cesarean section. Eclampsia is a severe complication of preeclampsia, a condition where the pregnant woman develops high blood pressure and protein in the urine. Eclampsia can cause seizures, coma, and death for the mother and the baby. The only cure for eclampsia is delivery of the baby, which may be vaginal or cesarean depending on the maternal and fetal condition.

Choice D reason: Total placenta previa is the correct answer, as it always requires delivery by cesarean section. Total placenta previa is a condition where the placenta completely covers the cervix, the opening of the uterus. This can cause painless bleeding, preterm labor, and fetal distress. Vaginal delivery is impossible and dangerous, as it can cause severe bleeding and damage to the placenta and the baby. Cesarean section is the only safe way to deliver the baby.