During a prenatal examination, an adolescent patient asks, "How does my baby get air?" The nurse would give correct information by saying:

Question

1. "The lungs of the fetus carry out respiratory gas exchange in utero similar to what an adult experiences."
2. "The placenta assumes the function of the fetal lungs by supplying oxygen and allowing the excretion of carbon dioxide into your bloodstream."
3. "The blood from the placenta is carried through the umbilical artery, which penetrates the abdominal wall of the fetus."
4. "The fetus is able to obtain sufficient oxygen due to the fact that your hemoglobin concentration is 50% greater during pregnancy."

Answer 1

2
Rationale 1: Most of the blood supply bypasses the fetal lungs, since they do not carry out respiratory gas exchange.
Rationale 2: The placenta assumes the function of the fetal lungs by supplying oxygen and allowing the excretion of carbon dioxide into the maternal bloodstream.
Rationale 3: The blood from the placenta is carried through the umbilical vein, not the umbilical artery.
Rationale 4: Fetal hemoglobin facilitates obtaining oxygen from the maternal circulation because it carries as much as 20% to 30% more oxygen than does adult hemoglobin.