Tissue swelling, or edema, is a common occurrence during pregnancy, especially during the last trimester. A certain level of edema is normal during pregnancy due to circulating pregnancy-related hormones and associated changes in body salt and water balance. Marked increases in edema or swelling in one area, however, may indicate a medical problem. Pregnant women who notice a sudden change in edema require medical evaluation.
Venous Compression
The enlarging womb may compress the veins returning blood from the legs to the heart, notes Merck Manuals Online Medical Library. Compression increases the pressure within the leg veins by impeding blood flow. Pooling of venous blood in the legs can lead to fluid leakage into the soft tissues with increased lower leg and foot edema. Venous compression is most likely to occur while lying down on the back, as the weight of the womb rests against the veins. This pressure can usually be reduced by lying on the side rather than the back.
Preeclampsia
Preeclampsia, also known as toxemia, is a pregnancy-related condition marked by high blood pressure and protein in the urine after the 20th week of pregnancy. In a 2004 review article published in "American Family Physician," Dr. Lana Wagner reports that preeclampsia develops in approximately 5 to 7 percent of pregnancies. Rapidly increasing edema and weight gain may signal the development of preeclampsia, notes Wagner. Increasing facial and hand edema may be more easily discerned than increases in preexisting edema of the feet and ankles.
Preeclampsia may endanger the health of the mother and her unborn baby, especially if complications ensue such as kidney failure, seizures, low platelet count and liver inflammation. Other symptoms may include headache, abdominal pain and blurred vision. Risk factors for the development of preeclampsia include gestational diabetes and diabetes mellitus, preexisting high blood pressure, obesity, carrying more than one baby, first pregnancy, maternal age older than 35 or younger than 20 years and a history of preeclampsia with a previous pregnancy.
Deep Venous Thrombosis
Deep venous thrombosis is the spontaneous formation of a blood clot in a deep vein. Pregnancy increases the risk for development of a deep venous thrombosis, or DVT, reports Dr. Lee Dresang and colleagues in a 2008 review article published in "American Family Physician." DVTs in pregnant women occur in the left leg in 78 to 90 percent of cases, notes Dresang. The formation of a DVT typically presents as increased swelling in the affected leg, which may be accompanied by pain.
Risk factors for the development of pregnancy-related DVT include obesity, being older than 35 years of age, vomiting and dehydration, bed rest or immobility, preexisting clotting disorder, heart or kidney disease, preeclampsia and trauma. DVT is a serious concern, as part of the clot may dislodge and obstruct the lung blood vessels. This condition, known as a pulmonary embolism, may be life-threatening for the mother and the unborn baby.
References
- Merck Manuals: Lower-Extremity Edema During Late Pregnancy
- "American Family Physician"; Diagnosis and Management of Preeclampsia; Lana K. Wagner, M.D.; December 2004
- "American Family Physician"; Venous Thromboembolism During Pregnancy; Lee T. Dresang, M.D., et al.; June 2008
- Cecil Textbook of Medicine: Pregnancy: Hypertension and Other Common Medical Problems
- American Pregnancy Association: Swelling During Pregnancy
