A nurse is calculating the partial pressure of oxygen (PaO2) in the arterial blood of a pregnant client who is in her second trimester.

The nurse should use which of the following values as the normal range for PaO2 in pregnancy?

Increased renal blood flow is responsible for the increased urinary output during pregnancy.

This is because the renal plasma flow and glomerular filtration rate increase by 50% to 80% during pregnancy, resulting in more urine production.

Choice A is wrong because the glomerular filtration rate increases, not decreases, during pregnancy.

Choice B is wrong because the tubular reabsorption decreases, not increases, during pregnancy.

This is due to the increased levels of progesterone, which inhibit sodium reabsorption and cause diuresis.

Choice D is wrong because the increased plasma volume is a consequence, not a cause, of the increased renal blood flow.

The plasma volume expands by 30% to 50% during pregnancy to meet the increased metabolic demands of the mother and fetus.

Back pain is a common symptom experienced due to increased muscle strain during pregnancy.

As the uterus grows and the center of gravity shifts, there is more pressure on the lower back muscles and ligaments.

This can cause pain, difficulty with balance, and reduced activity.

Choice A is wrong because leg cramps are not caused by muscle strain, but by other factors such as dehydration, electrolyte imbalance, or compression of blood vessels.

Choice C is wrong because pelvic pain is not a typical symptom of musculoskeletal changes during pregnancy.

Pelvic pain can be caused by other conditions such as urinary tract infection, preterm labor, or pelvic girdle pain.

Choice D is wrong because carpal tunnel syndrome is not a result of muscle strain, but of fluid retention and swelling that compresses the median nerve in the wrist.

This can cause numbness, tingling, or pain in the hand and fingers.