When many people think of an increased risk of blood clots, long plane trips and major surgery come to mind, not so much routine pregnancies and childbirth.

But deep vein thrombosis (DVT), a blood clot deep in the body, occurs during pregnancy or soon after childbirth in about 1 in 1,000 cases. If a blood clot moves through the blood vessels to the lungs, it becomes a dangerous condition called a pulmonary embolism (PE). Blood clots are the seventh leading cause of maternal death.

We’ve employed a coordinated, consistent approach to identify women at higher risk of DVT, which includes an assessment for admitted OB patients. Once the doctor knows the patient's risk level, he or she can order whatever preventive measures are needed. The main goal is early intervention.

It's good to repeat the DVT risk assessment at least every trimester in case the risk has changed. If the patient's risk is low, it may just be a matter of increasing her activity level. Other women may need elastic stockings, or a sequential compression device (SCD) that keeps the blood flowing by squeezing the leg muscles.

While all pregnant women have an elevated risk of DVT, that risk can be even greater during the month after childbirth because of blood loss and vascular injury during the birth. Anticoagulants are more commonly given to women after giving birth than they are during pregnancy.

Factors that can boost a pregnant woman's DVT risk include: extended bed rest, limited mobility, obesity, smoking, pregnancy with multiples, age over 35, infections, hypertension, personal or family history of blood clots, past use of birth control pills and thrombophilia (a sometimes hereditary condition that predisposes a person to blood clots).

Women who are planning to become pregnant can get a head start on risk reduction by losing excess weight, quitting smoking if that's an issue and learning about any family history of blood clots.

While DVT can occur without symptoms, the most common symptoms are pain and swelling, usually in one leg, with warm, reddened skin in the affected area. Diagnosis of a DVT may involve imaging tests, such as an ultrasound or an MRI. If a pulmonary embolism has developed, there may be shortness of breath, chest pain and rapid heartbeat.

The bottom line is, if you have any concerns about a blood clot, seek medical attention.

Learn more about high-risk pregnancies.

Donald Taylor, DO, is a maternal fetal medicine specialist with DuPage Medical Group/Maternal Fetal Medicine and medical director of Edward Hospital's Maternal Fetal Medicine Clinic.