During pregnancy, the center of gravity shifts forward as the uterus grows, causing an increased lordosis (inward curvature) of the lumbar spine.

This can lead to back pain and discomfort.

Choice A is wrong because increased joint laxity is due to hormonal changes that relax the ligaments and tendons, not the muscles.

Choice C is wrong because increased muscle strain is a result of increased spinal curvature, not a cause.

Choice D is wrong because decreased muscle strength is not a musculoskeletal change during pregnancy, but a possible consequence of reduced physical activity or poor nutrition.

Spinal curvature is expected to be at its highest point during the third trimester of pregnancy because of the increased weight of the fetus and the relaxation of the ligaments in the pelvic area due to pregnancy hormones.

This can cause backaches and discomfort for the pregnant woman.

Choice A is wrong because joint laxity is not specific to the third trimester of pregnancy.Joint laxity occurs throughout pregnancy due to the effects of relaxin and other hormones on the connective tissue that holds the bones in place.

Choice C is wrong because muscle strain is not a musculoskeletal change, but a possible consequence of the changes in posture and balance that occur during pregnancy.Muscle strain can affect any trimester of pregnancy, depending on the physical activity and fitness level of the woman.

Choice D is wrong because muscle strength is not a musculoskeletal change, but a factor that can influence the ability to cope with the changes in weight and posture that occur during pregnancy.Muscle strength can vary depending on the exercise regimen and nutrition of the woman.

This is because pelvic pain during pregnancy is typically caused by the release of a hormone calledrelaxin, which acts by relaxing the hip and pelvic ligaments and joints to make room for the growing baby.This hormone is released in higher quantities during labor to ease the passage of the baby, and it may cause pelvic pain, which resolves after labor.

Choice B is wrong because increased spinal curvature does not cause pelvic pain, but rather lower back pain.

Choice C is wrong because increased muscle strain does not cause pelvic pain, but rather round ligament pain, which is a sharp or crampy pain in the lower abdomen or groin area.

Choice D is wrong because decreased muscle strength does not cause pelvic pain, but rather increases the risk of urinary incontinence and pelvic organ prolapse after delivery.

Normal ranges for relaxin levels vary depending on the stage of pregnancy and the laboratory method used.

However, some general ranges are:

• First trimester: 6.3 to 110 ng/mL

• Second trimester: 19.5 to 155 ng/mL

• Third trimester: 55 to 210 ng/mL

This symptom is most likely due to carpal tunnel syndrome, which is a common condition in pregnancy caused by fluid retention and swelling in the wrists that compresses the median nerve, which controls feeling and movement in the hand.

Some possible explanations for the other choices are:

• Choice A is wrong because increased joint laxity is caused by the hormone relaxin, which loosens the ligaments and joints to prepare for childbirth.This can cause pain and instability in the pelvis, hips, and lower back, but not numbness and tingling in the hands.

• Choice B is wrong because increased spinal curvature is a result of the growing uterus and shifting center of gravity, which can cause back pain and posture changes, but not numbness and tingling in the hands.

• Choice D is wrong because decreased muscle strength is not a common symptom of pregnancy, unless it is due to an underlying condition such as anemia or thyroid problems.Numbness and tingling in the hands can affect grip strength and finger dexterity, but this is a consequence of carpal tunnel syndrome, not a cause.

Normal ranges for fluid retention and swelling in pregnancy vary depending on the individual, but some signs of excessive or abnormal swelling include sudden or severe swelling in the face, hands, or feet; swelling that does not go down after resting or elevating the limbs; or swelling that is accompanied by other symptoms such as headache, vision changes, or high blood pressure.These could indicate a serious condition such as preeclampsia, which requires immediate medical attention.