High-Risk Pregnancy
Sickle Cell Disease
Sickle
cell disease is an inherited blood disorder characterized by defective
hemoglobin (a protein in red blood cells that carries oxygen to the
tissues of the body).
Sickle cell disease
involves the red blood cells, or hemoglobin, and their ability to carry
oxygen. Normal hemoglobin cells are smooth, round, and flexible, like
the letter "O," so they can move through the vessels in our bodies
easily. Sickle cell hemoglobin cells are stiff and sticky, and form
into the shape of a sickle, or the letter "C," when they lose their
oxygen. These sickle cells tend to cluster together, and cannot easily
move through the blood vessels. The cluster causes a blockage and stops
the movement of healthy, normal oxygen-carrying blood. This blockage is
what causes the painful and damaging complications of sickle cell
disease.
Sickle cells only live for about
15 days, while normal hemoglobin can live up to 120 days. Also, sickle
cells risk being destroyed by the spleen because of their shape and
stiffness. The spleen is an organ that helps filter the blood of
infections and sickled cells get stuck in this filter and die. Due to
the decreased number of hemoglobin cells circulating in the body, a
person with sickle cell disease is chronically anemic. The spleen also
suffers damage from the sickled cells blocking healthy oxygen carrying
cells. Without a normal functioning spleen, these individuals are more
at risk for infections. Infants and young children are at risk for
life-threatening infections.
Sickle
cell disease is inherited. It is the result of a genetic mutation that
causes hemoglobin cells to be defective. This mutation is thought to
have originated in areas of the world where malaria was common, since
people with sickle trait do not get malaria. The sickle trait actually
offers some protection from the parasite that causes malaria, which is
carried by mosquitoes. Malaria is most often seen in Africa and in the
Mediterranean area of Europe.
Sickle cell
disease primarily affects those of African descent and Hispanics of
Caribbean ancestry, but the trait has also been found in those with
Middle Eastern, Indian, Latin American, Native American, and
Mediterranean heritage. In the US, it has been estimated that 1,000
children are born each year with sickle cell disease. One in twelve
African-Americans has sickle cell trait.
A
baby will be born with sickle cell disease only if two sickle cell
genes are inherited - one from the mother and one from the father. A
person who has only one sickle cell gene is healthy and said to be a
carrier of the disease. They may also be described as having sickle
cell trait. A carrier has an increased chance to have a baby with
sickle cell anemia. Once parents have had a child with sickle cell
disease, there is a one in four, or 25 percent, chance with each
subsequent pregnancy, for another child to be born with sickle cell
disease. This means that there is a three of four, or 75 percent,
chance for another child to not have sickle cell disease. There is also
a 50 percent chance that a child will be born with sickle cell trait,
like the parents.
The birth of a child
with sickle cell anemia is often a total surprise to a family, since
many times there is no previous family history of sickle cell disease.
Since both parents are healthy, they had no prior knowledge that they
carried the gene or were at risk for passing the gene on to a child.
Some
women have no change in their disease during pregnancy. However, sickle
cell crises (painful events) may still occur in pregnancy and may be
treated with medications that are safe to use during pregnancy.
Pre-existing kidney disease and congestive heart failure may worsen
during pregnancy, even with proper treatment.
The
risks for pregnancy depend on whether the mother has sickle cell
disease or sickle cell trait. Generally, women with sickle cell trait
are not at increased risk for problems, however, they may experience
frequent urinary tract infections. It is also important to remember
that, unlike sickle cell anemia, a woman with sickle cell trait can
have iron deficient anemia while pregnant and may need iron
supplementation for this reason.
The
ability of the blood cells to carry oxygen is especially important in
pregnancy. The sickling and anemia may result in lower amounts of
oxygen going to the fetus and slowed fetal growth. Because sickling
affects so many organs and body systems, women with the disease are
more likely to have complications in pregnancy. Complications and
increased risks for the mother may include, but are not limited to, the
following:
- infection, including urinary tract (especially kidney) and lungs
- gallbladder problems including gallstones
- heart enlargement and heart failure from anemia
Complications and increased risks for the fetus may include, but are not limited to, the following:
- miscarriage
- intrauterine growth restriction (poor fetal growth)
- preterm birth (before 37 weeks of pregnancy)
- low birthweight (less than 5.5 pounds)
- stillbirth and newborn death
Although
expectant mothers with sickle cell trait are not at higher risk for
pregnancy complications, the baby may be affected if the father also
carries the trait. Testing of the baby's father is recommended prior to
pregnancy, or at the first prenatal visit. If the baby's father has
sickle cell trait, amniocentesis (a procedure used to obtain a small
sample of the amniotic fluid) or other methods of prenatal diagnosis
may be offered to help determine if the fetus has the trait.
Early
and regular prenatal care is important for pregnant women with sickle
cell disease. More frequent prenatal visits allow for close monitoring
of the disease and of fetal well-being. General pregnancy care includes
a healthy diet, prenatal vitamins, folic acid supplements (a B
vitamin), and preventing dehydration.
Some
women may benefit from blood transfusions to replace the sickled cells
with fresh blood. These may be done several times during the pregnancy
to help increase the blood's ability to carry oxygen and decrease the
number of sickled cells. It is important for women who receive blood
transfusions to be screened for antibodies that may have been
transferred in the blood and that may affect her fetus.
- ultrasound (to measure fetal growth)
- nonstress test - measures fetal heart rate in response to fetal movement.
- biophysical profile - a test that combines an ultrasound with the nonstress test.
- Doppler flow studies - a type of ultrasound which use sound waves to measure blood flow.
During
labor, intravenous (IV) fluids are given to help prevent dehydration.
Most women will receive extra oxygen through a mask during labor and a
fetal heart rate monitor is often used to watch for changes in heart
rate and signs of fetal distress. There are no special recommendations
for the type of delivery for women with sickle cell disease and most
women can deliver vaginally, unless there are other complications.
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This content was reviewed by Mid-Atlantic Womens Care, PLC. Please visit their site to find an Mid-Atlantic Womens Care obstetrician.To locate a CHKD physician or practice, search our physician directory, or call (757) 668-7500 or (800) 395-2453, 8 a.m. to 5 p.m., Monday through Friday. You may also e-mail us at healthline@chkd.org.
Disclaimer:
This information is not intended to substitute or replace the professional medical advice you receive from your child's physician. The content provided on this page is for informational purposes only, and was not designed to diagnose or treat a health problem or disease. Please consult your child's physician with any questions or concerns you may have regarding a medical condition.
Last reviewed on 10/18/2006