A nurse is explaining the musculoskeletal changes during pregnancy to a group of expectant mothers.

Which change alters the center of gravity and posture of the body?

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.

Serum creatinine and urea are waste products of protein metabolism that are normally filtered by the kidneys and excreted in urine.

In pregnancy, the glomerular filtration rate (GFR) increases by about 50%, which means more creatinine and urea are cleared from the blood.Therefore, serum creatinine and urea levels decrease in pregnancy compared to nonpregnant women.

A. Increased serum creatinine and urea levels are wrong because they indicate impaired kidney function or dehydration, which are not normal in pregnancy.

C. Unchanged serum creatinine and urea levels are wrong because they do not reflect the increased GFR in pregnancy.

D. Increased glomerular filtration rate is correct but it is not a finding regarding serum creatinine and urea levels, which are the focus of the question.

Normal ranges for serum creatinine and urea vary depending on the laboratory and the units used, but based on a nonpregnant reference interval of 45-90 μmol/l (0.51-1.02 mg/dl) for creatinine and 2.5-6.4 mmol/l (7-18 mg/dl) for urea, a serum creatinine of >77 μmol/l (0.87 mg/dl) and a blood urea of >8.5 mmol/l (24 mg/dl) should be considered outside the normal range for pregnancy.