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?

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.

This change alters the center of gravity and posture of the body because the uterus expands and shifts higher as the fetus grows during pregnancy.

This causes an increased strain on the muscles and ligaments supporting the vertebral column and leads to lower back pain.

Choice A is wrong because increased joint laxity does not alter the center of gravity and posture of the body.

It is caused by hormonal changes that loosen the ligaments throughout the body, resulting in decreased stability of the joints.

Choice C is wrong because increased muscle strain does not alter the center of gravity and posture of the body.

It is a consequence of the shift in the center of gravity and the weight gain during pregnancy, which put more pressure on the back muscles.

Choice D is wrong because decreased muscle strength does not alter the center of gravity and posture of the body.

It is not a common musculoskeletal change during pregnancy, although some women may experience fatigue or weakness due to hormonal changes or anemia.