Sickle cell disease (also called SCD) is a condition in which the red blood cells in your body are shaped like a sickle (like the letter C).

Red blood cells carry oxygen to the rest of your body. In a healthy person, red blood cells are round and flexible. They flow easily in the blood. A person with SCD has red blood cells that are stiff and can block blood flow. This can cause pain, infections and, sometimes, organ damage and strokes.

SCD may lead to anemia. Anemia happens when you don’t have enough healthy red blood cells to carry oxygen to the rest of your body.

What causes SCD?

SCD is inherited. This means it’s passed from parent to child through genes. A gene is a part of your body’s cells that stores instructions for the way your body grows and works. Genes come in pairs — you get one of each pair from each parent.

Sometimes the instructions in genes change. This is called a gene change or a mutation. Parents can pass gene changes to their children. Sometimes a gene change can cause a gene to not work correctly. Sometimes it can cause birth defects or other health conditions. A birth defect is a health condition that is present in a baby at birth.

You have to inherit a gene change for sickle cell from both parents to have SCD. If you inherit the gene change from just one parent, you have sickle cell trait. This means that you have the gene change for SCD, but you don’t have SCD. When this happens, you’re called a carrier. A carrier has the gene change but doesn’t have the condition.

Sickle cell trait cannot become SCD. Rarely people with sickle cell trait show signs of SCD, but this is unusual. Most don’t.

Can you pass SCD or sickle cell trait to your children?

Yes. But it depends on both you and your partner. If you and your partner both have SCD, your baby will have SCD.

If you and your partner both have sickle cell trait, there’s a:

  • 3-in-4 chance (75 percent) that your baby won’t have SCD
  • 1-in-2 chance (50 percent) that your baby will have sickle cell trait
  • 1-in-4 chance (25 percent) that your baby will have SCD
  • 1-in-4 chance (25 percent) that your baby won’t have SCD or sickle cell trait

A genetic counselor can help you understand your chances of passing SCD or sickle cell trait to your baby. A genetic counselor is a person who is trained to help you understand about how genes, birth defects and other medical conditions run in families, and how they can affect your health and your baby's health.

Ask your health care provider if you need help finding a genetic counselor. Or contact the National Society of Genetic Counselors.

How can you find out if you have SCD or sickle cell trait?

There are two types of tests that can tell you if you have SCD or sickle cell trait. Both are safe to take during pregnancy. Your partner can have the tests, too.

  1. A blood test
  2. A swab of cells inside your mouth. This means your provider rubs a cotton swab against the inside of your cheek to get some cells.

You and your partner may want to be tested if:

  • SCD or sickle cell trait runs in either of your families. To help you find out, take your family health history. This is a record of any health conditions and treatments that you, your partner and everyone in both of your families have had. Use this family health history form and share it with your health care provider.
  • You’re black or Hispanic. In the United States, SCD is most common among these groups. SCD affects about 1 in 500 black births and about 1 in 36,000 Hispanic births in this country.
  • Your family’s ancestors are from Africa, the Caribbean, Greece, India, Italy, Malta, Sardinia, Saudi Arabia, Turkey, or South or Central America.

Can you find out if your baby has SCD or sickle cell trait during pregnancy?

Yes. If you or your partner has SCD or sickle cell trait, you can have a prenatal test to find out if your baby has SCD or sickle cell trait.

You can have either of these tests:

  • Chorionic villus sampling (also called CVS). This test checks tissue from the placenta for birth defects and genetic conditions. You can get CVS at 10 to 13 weeks of pregnancy.
  • Amniocentesis (also called amnio). This test checks amniotic fluid from the amniotic sac around your baby for birth defects and genetic conditions. You can get this test at 15 to 20 weeks of pregnancy.

Talk to your provider or genetic counselor if you’re thinking of having either of these tests.

Can SCD cause problems during pregnancy?

With regular prenatal care, most women with SCD can have a healthy pregnancy. But if you have SCD, you’re more likely than other women to have health complications that can affect your pregnancy. These complications include pain episodes, infection and vision problems.

During pregnancy, SCD may become more severe, and pain episodes may happen more often. Pain episodes usually happen in the organs and joints. They can last a few hours to a few days, but some last for weeks.

During pregnancy, SCD may increase your risk of:

  • Miscarriage, when a baby dies in the womb before 20 weeks of pregnancy
  • Premature birth, when birth happens too early, before 37 weeks of pregnancy
  • Having a baby with low birthweight (less than 5 pounds, 8 ounces)

How is SCD treated during pregnancy?

If you have SCD and you’re pregnant or planning to get pregnant, talk to your health care provider about the medicines you’re taking. Your provider may change your medicine to one that’s safe for your baby during pregnancy.

For example, hydroxyurea is a medicine that may help prevent red blood cells from sickling. It’s used to treat SCD pain episodes. However, it isn’t recommended during pregnancy because it may increase the risk of birth defects.

Your provider also can treat other problems related to SCD and pregnancy. For example, your provider can help you find ways to treat pain episodes that are safe during pregnancy.

More information

See also: Genetic counselingYour family health historyNewborn screening

Last reviewed: January, 2013