Pain in the calf when you're pregnant generally occurs for one of two reasons, one quite serious and one merely annoying. Leg cramps or muscle spasms -- the merely annoying type of pain -- often cause calf pain during the night when you're pregnant. Calf pain that doesn't go away with simple measures could mean you have a deep vein thrombosis, a serious complication that occurs in 1 or 2 of 1,000 pregnant women, according to Lifeblood: The Thrombosis Charity website. Seek immediate medical attention if you have persistent calf pain during pregnancy.
Leg cramps that wake you out of a sound sleep are usually caused by muscle spasms. This type of leg cramp is more common than the more serious deep vein thrombosis. Possible causes of leg cramps include pressure on nerves from the baby's head, decreased levels of calcium and magnesium in your blood, swelling in the lower extremities that puts pressure on nerves and the increased workload on your muscles during later pregnancy. Pain from deep vein thrombosis, also known as thrombophlebitis -- which can occur day or night -- occurs for two reasons. When you're pregnant, your blood clots more easily. And because blood flow slows from the weight of the uterus on the veins of the pelvis and lower leg during pregnancy, blood flow slows, making clots more likely to form.
Differentiating Between Types
Leg cramps that occur in the night or when you've been sitting with your leg in a position that temporarily blocks blood flow, causing "pins and needles" tingling, is usually easily improved. Stand up, walk around, flex your feet or massage the aching muscle and the pain generally subsides. The pain of deep vein thrombosis will not dissipate with these measures. You may also notice warmth in the calf, redness, swelling or tenderness to touch. If the leg hurts constantly rather than sporadically or if it's tender to touch, call your doctor.
Leg cramps or muscle spasms that occur during night and subside with simple treatment have no long-term complication outside of interfering with sleep. Deep vein thrombosis, on the other hand, can have serious consequences. A blood clot can break loose and travel to the lungs, lodging in the lung and blocking blood flow. This condition, called a pulmonary embolus, causes difficulty breathing, tightness in the chest or sudden collapse. Call 911 immediately if you develop these symptoms when pregnant or in the first six weeks after delivery, the most common time for DVT to occur, according to the Royal College of Obstetricians and Gynaecologists.
Prevention and Treatment
Leg cramps normally subside quickly, but may occur frequently at night. Regular exercise may help, but leg cramps are notoriously difficult to prevent and treat, obstetrician Gerard M. DiLeo says on his website Gynob.com. Taking calcium or magnesium supplements does not appear to help. Pregnancy increases your risk of deep vein thrombosis tenfold over women of the same age who are not pregnant, the Royal College of Obstetricians and Gynaecologists reports. Women older than 25, overweight women, smokers and women with a history of blood clots or health disorders such as heart or lung disease have a higher risk of developing DVT. Immobility during pregnancy can also increase your risk. Heparin, a injected blood thinner, prevents the clot from enlarging and helps prevent another from developing.