Leg cramps are painful muscle contractions that typically affect the calf, foot or both.

They are common during pregnancy, often happening at night during the second and third trimesters.

While the exact cause of leg cramps during pregnancy isn’t clear, various theories point to the following causes of leg cramps during pregnancy: 2

Pregnancy fatigue from carrying the extra baby weight

Compression of the blood vessels in the legs

Diet (an excess of phosphorus and a shortage of calcium or magnesium)

Pregnancy hormones since they seem to cause so many pregnancy aches and pains

Choice A is wrong because increased joint laxity is not a cause of leg cramps, but rather a result of hormonal changes that relax the ligaments and joints in preparation for childbirth.

Choice B is wrong because increased spinal curvature is not a cause of leg cramps, but rather a result of the changing center of gravity and posture during pregnancy.

Choice D is wrong because decreased muscle strength is not a cause of leg cramps, but rather a consequence of muscle fatigue and weight gain during pregnancy.

Normal ranges for calcium are 8.5 to 10.2 mg/dL, for magnesium are 1.7 to 2.2 mg/dL, and for phosphorus are 2.5 to 4.5 mg/dL.