In general, pregnancy (including postpartum) increases the risk of a blood clot.

Are there different kinds of blood clots involved with pregnancy?

DVT: Deep Vein Thrombosis

This develops in the deep veins, rather than superficial or subcutaneous vessels. Typically, a DVT forms in one leg (usually lower, but it can be upper).

This type of blood clot comprises around 75 percent of DVTs that occur during, or immediately following, a pregnancy.

Symptoms of a DVT: redness, swelling, tenderness and/or warmth of the affected area (most often lower leg). Any pain or soreness is present during rest, not just when walking.

Pregnant women are prone to bilateral leg swelling, but should keep close tabs on their legs for the possibility of a blood clot.

The swelling caused by a DVT will not look like the normal edema that so often occurs during pregnancy.

The pain may resemble a severe cramp or even feel like a pulled muscle.

Risk factors other than pregnancy include obesity, smoking, prolonged bed rest and excessive sitting.

Pulmonary Embolism (Embolus)

This originates as a deep vein thrombosis; it occurs when a portion of, or an entire, DVT breaks loose from its point of origin, and migrates into one or both lungs.

A pulmonary embolism (PE) makes up about 25 percent of blood clots related to pregnancy.

For how long after pregnancy is a woman at risk for deep vein thrombosis?

For up to six weeks after delivery. However, the risk of DVT during pregnancy is triple over that of postpartum.

About 50 percent of patients who have a blood clot during pregnancy experience this around the fourth month, or around the start of the second trimester.

Interestingly, around 60 percent of PE cases develop soon after a woman gives birth, as well as within six weeks of delivery.

Source: The National Alliance for Thrombosis and Thrombophilia newsletter at stoptheclot.org/Newsletters/FINAL_Spring%20Summer%2008%20Nwsl_WEB.pdf