Thrombophilias are health conditions that increase your chances of making abnormal blood clots. A blood clot (also called a thrombosis) is a clump of blood that forms when blood changes from a liquid to a solid. The body normally makes blood clots to stop the bleeding after a scrape or cut. If you have a thrombophilia, your body may make extra clots in your blood vessels. This can cause health problems during pregnancy. About 1 in 5 people (20 percent) in the United States has a thrombophilia.
Most women with thrombophilias have healthy pregnancies. But thrombophilias may cause problems for some pregnant women. In severe cases, they can cause death for both mom and baby. This is why it’s important to learn about thrombophilias. If you’re at risk of having a thrombophilia, testing and treatment can help save both you and your baby.
If you’re pregnant or trying to get pregnant and you know you have a thrombophilia, tell your health care provider at a preconception checkup (before pregnancy) or at your first prenatal care checkup. Also tell your provider if someone in your family (a parent, brother or sister) has a thrombophilia or other clotting problems. This means that thrombophilias may be in your family history (run in your family). If you have a family history of these conditions, talk to your provider to see if you need a blood test to check for a thrombophilia.
What problems can thrombophilias cause in pregnancy?
If you have a certain kind of thrombophilia called antiphospholipid syndrome (also called APS), you may be more likely to have pregnancy complications, including:
- Intauterine growth restriction (also called IUGR). This is when your baby grows poorly in the womb.
- Placental insufficiency. The placenta grows in your uterus (womb) and supplies the baby with food and oxygen through the umbilical cord. Placental insufficiency means the placenta doesn’t work as well as it should so your baby gets less food and oxygen.
- Preeclampsia. This condition happens after the 20th week of pregnancy or right after pregnancy. It’s when a pregnant woman has both protein in her urine and high blood pressure.
- Premature birth. This is when your baby is born before 37 weeks of pregnancy.
- Miscarriage. A miscarriage is when a baby dies in the womb before 20 weeks of pregnancy.
- Stillbirth. This is when a baby dies in the womb before birth but after 20 weeks of pregnancy.
APS is an acquired thrombophilia. This means it’s not inherited but develops on its own. Researchers are trying to find out if inherited thrombophilias may lead to the same kinds of pregnancy complications.
Who is at risk for having a thrombophilia?
Some pregnancy complications may make it more likely for a woman to have a thrombophilia. For example, you may be at risk for a thrombophilia if you’ve had:
- Three or more miscarriages before 10 weeks of pregnancy and the cause is unknown; or if you’ve had a miscarriage after 10 weeks of pregnancy and the cause is unknown
- A stillbirth
- One or more babies born before 34 weeks of pregnancy because of eclampsia (seizures during pregnancy), severe preeclampsia or a problem with the placenta
- A thrombosis or you develop one during pregnancy
If you’ve had any of these complications, talk to your provider to see if you need to get tested for a thrombophilia. Treatment before and during pregnancy can help you have a healthy pregnancy and a healthy baby.
How do you know if you have a thrombophilia?
There are different kinds of blood tests for different thrombophilias. If you’ve had blood clotting problems or if you have a family history of thrombophilias, talk to your provider to see if you need to get tested for an inherited thrombophilia.
Most people with a thrombophilia have no signs or symptoms. The first sign may be that you develop a health condition related to a blood clot, including:
Thrombosis. This happens when a blood clot forms in a blood vessel and blocks blood flow. It most often happens in the deep veins of the legs but can be in other places of the body:
- Cerebral vein thrombosis (also called CVT). This kind of thrombosis happens when a blood clot forms in a vein in the brain. Signs and symptoms include a headache that doesn’t go away, vision problems and seizures.
- Deep vein thrombosis (also called DVT). This kind of thrombosis happens when a blood clot forms in a vein deep in the body, usually in the lower leg or thigh. Signs and symptoms include warmth and tenderness over the vein and pain, swelling or skin redness in the area of the clot.
Pulmonary embolism (also called PE). An embolism is a blood clot that moves from where it formed to another place in the body. When the clot moves to a lung, it’s a PE. PE can cause low oxygen levels in your blood and damage your body organs. It’s an emergency and a leading cause of death during pregnancy. Signs and symptoms of PE may include trouble breathing, fast or irregular heartbeat, chest pain, fainting, feeling anxious or coughing up blood.
Venous thromboembolism (also called VTE). This happens when a blood clot breaks off and travels through blood to major organs like the brain, lungs or heart. This condition includes DVT and PE. VTEs that block blood vessels in the brain or heart can cause stroke or heart attack.
Your provider may use ultrasound or tests like magnetic resonance imaging (also called MRI) to see if you have these conditions. Ultrasound uses sound waves and a computer screen to make a picture of a baby in the womb. MRI uses magnets and computers to make a clear picture of the inside of the body. These tests are painless and safe for you and your baby.
How are thrombophilias treated?
Treatment depends on:
Your provider may refer you to a hematologist if you don’t already have one. This is a doctor who treats blood conditions.
Some women may need treatment with medicine called blood thinners. Blood thinners stop clots from getting bigger and prevent new clots from forming. You may need this treatment if you’ve had a VTE before or you have a high-risk thrombophilia. You may get a blood thinner called heparin (low-molecular weight heparin or unfractionated heparin). If you have APS and have had miscarriages, your provider may give you low-dose aspirin and heparin to help prevent another miscarriage.
During pregnancy, you may need to go for prenatal care checkups more often than women who don’t have a thrombophilia. At these visits, your provider checks your blood pressure and can use other tests, like blood tests, to monitor your condition.
Your provider also may use these tests to check your baby’s health in the womb:
- Ultrasound. Your provider uses ultrasound to check your baby’s growth and development. She may use a special kind of ultrasound called Doppler ultrasound to check your baby’s blood flow in the umbilical artery, a blood vessel in the umbilical cord. The umbilical cord connects your baby to the placenta. It carries food and oxygen from the placenta to the baby.
- Fetal heart rate monitoring (also called a nonstress test or NST). This test checks your baby’s heart rate in the womb and how the heart rate changes when your baby moves. Your provider uses this test to make sure your baby’s getting enough oxygen.
After you give birth, your provider may continue to treat you with heparin. Or he may treat you with a blood thinner called warfarin. Warfarin is safe to take after pregnancy, even if you’re breastfeeding. Warfarin is not safe to take during pregnancy because it may cause birth defects.
You may use birth control after pregnancy to help keep you from getting pregnant again. But some kinds of birth control, like the pill, may increase your risk of having blood clots and not be safe for you to use. If you have a thrombophilia or blood clotting problems or if you have a family history of these conditions, talk to your provider about other birth control options.
What causes thrombophilias?
You have a thrombophilia if your body makes either too much of certain proteins or too little of other proteins that help make clots.
An acquired thrombophilia is not inherited but develops on its own. The most common acquired thrombophilia is APS. APS is an autoimmune disorder similar to lupus. When you have an autoimmune disorder, antibodies (cells in your body that fight off infections) attack healthy tissue by mistake. If you have APS, your body makes antibodies that attack certain fats that line the blood vessels. This can sometimes cause blood clots. APS happens in up to 5 in 100 (5 percent) pregnant women.
When a thrombophilia is inherited, it’s passed from parent to child through changes (also called mutations) in genes. A gene is a part of your body’s cells that stores instructions for the way your body grows and works. Changes in certain genes make it more likely for you to have a thrombophilia. These changes include:
- Factor V Leiden thrombophilia
- Prothrombin thrombophilia
- Protein C deficiency
- Protein S deficiency
- Antithrombin deficiency
For more information
The Shane Foundation
Last reviewed January 2014
See also: Blood clots and pregnancy, Maternal death
Most common questions
What is mononucleosis?
Mononucleosis (also called mono) is an infection usually caused by the Epstein-Barr virus (EBV). It’s sometimes caused by another virus called cytomegalovirus (CMV). EBV and CMV are part of the herpes virus family. Mono is most common in teenagers and young adults, but anyone can get it. Mono is called the “kissing disease” because it’s usually passed from one person to another through saliva. In addition to kissing, it can also be passed through sneezing, coughing or sharing pillows, drinks, straws, and toothbrushes.
You can have mono without having any symptoms. But even if you don’t get sick, you can still pass it to others. Symptoms can include:
- Achy muscles
- Belly pain
- Fatigue (feeling tired all the time)
- Sore throat
- Swollen glands in your neck
If your symptoms don’t go away or get worse, tell your health care provider. He’ll most likely do a physical exam and test your blood to find out for sure if you have mono.
There’s no vaccine to prevent mono. There’s also no specific treatment. The best care is to take it easy and get as much rest as you can. It may take a few weeks before you fully recover.
Can Rh factor affect my baby?
The Rh factor may be a problem if mom is Rh-negative but dad is Rh-positive. If dad is Rh-negative, there is no risk.
If your baby gets her Rh-positive factor from dad, your body may believe that your baby's red blood cells are foreign elements attacking you. Your body may make antibodies to fight them. This is called sensitization.
If you're Rh-negative, you can get shots of Rh immune globulin (RhIg) to stop your body from attacking your baby. It's best to get these shots at 28 weeks of pregnancy and again within 72 hours of giving birth if a blood test shows that your baby is Rh-positive. You won't need anymore shots after giving birth if your baby is Rh-negative. You should also get a shot after certain pregnancy exams like an amniocentesis, a chorionic villus sampling or an external cephalic version (when your provider tries to turn a breech-position baby head down before labor). You'll also want to get the shot if you have a miscarriage, an ectopic pregnancy or suffer abdominal trauma.
I had a miscarriage. How long should I wait to try again?
Before getting pregnant again, it's important that you are ready both physically and emotionally. If you don't need tests or treatments to discover the cause of the miscarriage, it's usually OK for you to become pregnant after one normal menstrual cycle. However, it may take longer for you to feel emotionally ready to be pregnant again. Everyone responds differently to a miscarriage. Only you will know when you are ready to try to get pregnant again.
Are gallstones common during pregnancy?
Not common, but they do happen. Elevated hormones during pregnancy can cause the gallbladder to function more slowly, less efficiently. The gallbladder stores and releases bile, a substance produced in the liver. Bile helps digest fat. When bile sits in the gallbladder for too long, hard, solid nuggets called gallstones can form. The stones can block the flow of bile, causing indigestion and sometimes serious pain. Staying at a healthy weight during pregnancy can help lower your risk of gallstones. Exercise and eating foods that are low in fat and high in fiber, like veggies, fruits and whole grains, can help, too. Symptoms of gallstones include nausea, vomiting and intense, continuous abdominal pain. Treatment during pregnancy may include surgery to remove the gallbladder. Gallstones in the third trimester can be managed with a strict meal plan and pain medication, followed by surgery several weeks after delivery.