As pregnancy progresses, fluid may accumulate in tissues, usually in the feet, ankles, and lower legs, causing them to swell and appear puffy. Some fluid accumulation during pregnancy is normal, particularly during the 3rd trimester. This condition is called edema Swelling Swelling is due to excess fluid in the tissues. The fluid is predominantly water. Swelling may be widespread or confined to a single limb or part of a limb. Swelling is often in the feet and... read more 
. Occasionally, the fingers also have mild swelling. If swelling is more than mild in the hands or if there is swelling in the face, the woman should be evaluated by a doctor.
Fluid accumulates during pregnancy because the adrenal glands produce more of the hormones that make the body retain fluids (aldosterone and cortisol). Fluid also accumulates because the enlarging uterus interferes with blood flow from the legs to the heart. As a result, fluid backs up in the veins of the legs and seeps out into the surrounding tissues.
Causes of Swelling in Late Pregnancy
Common causes
Usually during pregnancy, swelling is
Normal, pregnancy-related edema
Less common causes
Less commonly, swelling during pregnancy results from a disorder (see table ). Such disorders can be serious. They include the following;
Peripartum cardiomyopathy Peripartum cardiomyopathy Most women who have heart disorders—including certain heart valve disorders (such as mitral valve prolapse) and some birth defects of the heart—can safely give birth to healthy children, without... read more (heart failure that develops late in pregnancy or after delivery)
In preeclampsia, a disorder that occurs only during pregnancy, blood pressure and protein levels in urine increase. Fluids may accumulate, causing swelling in the face, hands, or feet and additional weight gain; most, but not all, women with preeclampsia have swelling. If severe, preeclampsia can damage organs, such as the brain, kidneys, lungs, or liver, and cause problems in the baby.
In deep vein thrombosis, blood clots form in veins located deep within part of the body, often in the legs. Pregnancy increases the risk of this disorder in several ways. During pregnancy, the body produces more of the proteins that help blood clot (clotting factors), probably intended to prevent too much bleeding during childbirth. Also, changes during pregnancy cause blood to back up in veins, making clots more likely to form. If the pregnant woman is less mobile, blood is even more likely to back up in leg veins and clot. The clots may interfere with blood flow. If a blood clot breaks loose, it can travel through the bloodstream to the lungs, blocking blood flow there. This blockage (called pulmonary embolism Pulmonary Embolism (PE) Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more ) is life threatening.
Peripartum cardiomyopathy is a rare but serious condition that causes shortness of breath and fatigue, as well as swelling.
Risk factors
The risk of preeclampsia, deep vein thrombosis, and peripartum cardiomyopathy are increased by various conditions (risk factors).
High-risk factors for preeclampsia include
Preeclampsia during a previous pregnancy
A pregnancy with more than one fetus
Kidney disorders
Molar pregnancy Molar Pregnancy A molar pregnancy (hydatidiform mole) and other types of gestational trophoblastic disease are growth of an abnormal fertilized egg or an overgrowth of tissue from the placenta. Women with a... read more (abnormal growth of the placenta with or without a fetus due to an abnormally fertilized egg)
Moderate-risk factors for preeclampsia include
First pregnancy
Obesity
Family history of preeclampsia
African ancestry
Lower income
Age 35 or older
In vitro fertilization
Personal history factors (for example, previous infants with low birth weight or small for gestational age, previous adverse pregnancy outcome, more than 10 years between pregnancies)
For deep vein thrombosis, risk factors include the following:
A previous episode of deep vein thrombosis
Inherited blood clotting disorders
Injury to a leg vein Chronic Venous Insufficiency and Postphlebitic Syndrome Chronic venous insufficiency is damage to leg veins that prevents blood from flowing normally. Postphlebitic syndrome is chronic venous insufficiency that results from a blood clot in the veins... read more
that prevents blood from flowing normallyA disorder that makes blood more likely to clot, such as cancer or kidney or heart problems
Immobility, as may occur after an illness or surgery
Obesity
For peripartum cardiomyopathy, risk factors include the following:
Age 30 or older
African ancestry
A pregnancy with more than one fetus
Preeclampsia
Evaluation of Swelling in Late Pregnancy
Doctors must rule out deep vein thrombosis, preeclampsia, a heart disorder, and other possible causes before they can diagnose normal, physiologic edema.
Warning signs
In pregnant women with swollen legs, the following symptoms are cause for concern:
Moderate or severe swelling in the hands (hands look noticeably puffy and/or a ring cannot be removed from a finger)
Swelling that suddenly increases in any part of the body
Swelling in only one leg or calf, particularly if the area is warm, red, and/or tender or fever is present
Blood pressure that is 140/90 mm Hg or higher
Severe persistent headache, changes in vision, confusion, severe upper abdominal pain, or difficulty breathing—symptoms that may be caused by preeclampsia
Chest pain or difficulty breathing—symptoms that may be caused by deep vein thrombosis
When to see a doctor
Women should go to the hospital immediately if they have any of the warning signs.
Women without warning signs should see a doctor, but a delay of several days is usually not harmful.
What the doctor does
Doctors first ask questions about the swelling and other symptoms and about the medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the swelling and the tests that may need to be done (see table ).
Doctors ask the following:
When the swelling started
How long it has been present
Whether any activity (such as lying on the left side) lessens or worsens it
Doctors also ask about conditions that increase the risk of developing deep vein thrombosis Deep Vein Thrombosis (DVT) Deep vein thrombosis is the formation of blood clots (thrombi) in the deep veins, usually in the legs. Blood clots may form in veins if the vein is injured, a disorder causes the blood to clot... read more 
, preeclampsia Preeclampsia and Eclampsia Preeclampsia is new high blood pressure or worsening of existing high blood pressure that is accompanied by excess protein in the urine and that develops after the 20th week of pregnancy. Eclampsia... read more , and peripartum cardiomyopathy Peripartum cardiomyopathy Most women who have heart disorders—including certain heart valve disorders (such as mitral valve prolapse) and some birth defects of the heart—can safely give birth to healthy children, without... read more .
Women are asked about other symptoms, which may suggest a cause. They are asked whether they have ever had deep vein thrombosis, pulmonary embolism Pulmonary Embolism (PE) Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more , preeclampsia, high blood pressure, or heart problems, including cardiomyopathy.
During the physical examination, doctors look for evidence of a serious cause of the swelling. To check for symptoms of preeclampsia, doctors measure blood pressure, listen to the heart and lungs, and may check the woman's reflexes and look at the back of her eyes with an ophthalmoscope (a handheld device that resembles a small flashlight). Doctors also look for areas of swelling, particularly in the legs, hands, and face. Any swollen areas are checked to see if they are red, warm, or tender.
Testing
If preeclampsia is suspected, the protein level is measured in a urine sample, and a complete blood count, electrolytes, and tests of kidney and liver function are done. New-onset high blood pressure plus a high protein level in urine indicates preeclampsia. If the diagnosis is unclear, the woman is asked to collect her urine for 24 hours, and protein is measured in that volume of urine. High blood pressure with headache, changes in vision, abdominal pain, or abnormal blood or urine test results may also indicate preeclampsia.
If deep vein thrombosis is suspected, Doppler ultrasonography of the affected leg is done. This test can show disturbances in blood flow caused by blood clots in the leg veins.
If peripartum cardiomyopathy is suspected, electrocardiography, chest x-ray, echocardiography, and blood tests to check heart function are done.
Treatment of Swelling in Late Pregnancy
When swelling results from a disorder, that disorder is treated.
The swelling that occurs normally during pregnancy can be reduced by doing the following:
Lying on the left side, which moves the uterus off the large vein that returns blood to the heart (inferior vena cava)
Resting frequently with the legs elevated
Wearing elastic support stockings
Wearing loose clothing that does not restrict blood flow, particularly in the legs (for example, not wearing socks or stockings that have tight bands around the ankles or calves)
Key Points
Some swelling in the legs and ankles is normal (physiologic) during pregnancy and occurs during the 3rd trimester.
Doctors can identify serious causes of swelling based on results of a physical examination, blood pressure measurement, blood and urine tests, and sometimes ultrasonography.
If pregnancy itself is the cause, swelling can be reduced by lying on the left side, elevating the legs periodically, wearing support stockings, and wearing clothing that does not restrict blood flow.
