How does sickle cell anemia affect pregnancy?
August 6, 2019
Evolution is a curious thing. Sometimes a physical trait develops that protects people at first but becomes harmful over time. One example of this phenomenon is the genetic mutation that causes sickle cell anemia, or sickle cell disease (SCD).
SCD can affect anyone, but the trait is more common in people of African descent. In the U.S., 1 in 12 African-Americans carry this mutation, according to The Sickle Cell Association of Texas Marc Thomas Foundation. Research suggests the mutation was once protective against malaria, a viral illness spread by mosquitoes. In Uganda, for example, there is a correlation between frequency of this genetic mutation and the prevalence of certain types of malaria-carrying mosquitoes.
People of African ancestry living in the U.S. don’t need to worry about malaria, but the genetic mutation that causes sickle cell can lead to a range of health issues – from widespread pain to increased risk of infection – that complicate pregnancy and must be carefully managed.
If you or your partner carry the sickle cell mutation or have SCD, it’s important to understand how the condition can affect your health and what to expect during your complex but manageable pregnancy.
How does sickle cell disease affect your health?
The basics of SCD
A healthy red blood cell is round like a jelly donut. These cells are made of a substance called hemoglobin A, which helps carry oxygen to the tissues of the body. For most people, the blood is composed almost entirely of hemoglobin A.
But if you have the SCD gene mutation, your body creates hemoglobin A and hemoglobin S. Hemoglobin S makes the top of some red blood cells curve like a scythe or sickle (hence the name).
If you inherited the mutation from one of your parents, you are a carrier. Your blood likely is mostly composed of hemoglobin A with some hemoglobin S. You typically don’t have symptoms but can be at risk for some pregnancy complications.
If you inherited a mutation from both of your parents, you have sickle cell disease. Your blood is mostly composed of hemoglobin S. You likely have noticeable symptoms, which can increase during pregnancy.
When the abnormally shaped red blood cells carrying hemoglobin S try to go through small blood vessels in your body, they clump together. This can cause blockages that lead to ischemia, which means less oxygen reaches your vital organs and your growing baby. The lack of blood flow causes a sickle cell crisis – pain in your joints, legs, back, abdomen, or chest. Over time, SCD can lead to kidney issues, heart dysfunction, and stroke. Carriers and patients with SCD also are more prone to infection.
Treatment is focused on increasing the number of blood cells carrying hemoglobin A. Historically, blood transfusions were used for this purpose. Medications like hydroxyurea increase production of hemoglobin that doesn’t clump in small blood vessels and reduces the need for blood transfusions, pain crises, and hospitalizations. Prescription pain medication (opioids) or other therapies are used to manage pain during sickle cell crisis.
Related reading: An honest discussion about opioid use and pregnancy
SCD care and pregnancy
Although SCD causes many symptoms, most patients can safely navigate pregnancy with collaborative care between their hematologist and maternal-fetal medicine specialist.
Pregnant women with SCD are at increased risk for significant complications, including preterm delivery, fetal growth restriction, or stillbirth. Women should also prepare for potential hospitalization related to SCD complications. If you have other children or care for dependent adults, it’s a good idea to create a backup care plan.
Aside from the maternal health risks all pregnant women face, patients with SCD are more prone to infection. We will ask for extra urine specimens to watch for asymptomatic urinary tract infections, and we make sure you’ve been vaccinated for certain types of pneumonia.
Related reading: Why we discuss vaccines, maternal health during pregnancy
Since sickle cell disease is a genetic condition, your unborn child is at risk for being a carrier or affected by the disease. It’s important to know whether your partner carries the sickle cell mutation. Prenatal testing is available for the condition. If you aren’t interested in knowing prior to delivery, it’s comforting to know that all babies are screened at birth for SCD.
Some women will continue to require blood transfusions and medications – even opioids – during pregnancy. Blood transfusions are safe during pregnancy, and women have remained on hydroxyurea during pregnancy. Maternal side effects of opioids can include constipation, trouble sleeping, dizziness, and nausea. Long-term use of opioids in the mother may cause opioid withdrawal in the newborn, which is also called neonatal abstinence syndrome. Symptoms include irritability, seizures, poor feeding, and vomiting; treatment can require lengthy hospital stays for the baby.
Looking ahead in SCD treatment
Bone marrow transplantation is considered curative today. The procedure replaces sickle cells with healthy red blood cells. It is reserved for young patients with severe symptoms because of risks involved with the procedure, which increase after age 16. Pregnant patients who have had a bone marrow transplant have higher risks for preterm delivery but not complications related to anemia.
'In the future, we expect more therapies will be developed that focus less on managing SCD symptoms and more on curing the disease. Gene therapy might be the key.'
Ongoing research is giving adult patients hope. A study of 30 patients in 2014 found that a modified BMT procedure with reduced chemotherapy reversed or reduced symptoms in 87% of adult patients after more than three years. Cord-blood stem-cell transplantation is also promising.
In the future, we expect more therapies will be developed that focus less on managing SCD symptoms and more on curing the disease. The National Heart, Lung, and Blood Institute reports that gene therapy might be the key to patients developing normal red blood cells instead of sickle cells. In a clinical trial featured on 60 Minutes, doctors have found, altered, and replaced mutated cells in patients to support normal hemoglobin production – initial results are promising.