Early Blood Tests for Pregnancy

During the first trimester of pregnancy, a health care provider will take blood to determine the current health of the mother and record vital information that may be needed over the course of the pregnancy and delivery. A fetal screening blood test helps identify a pregnancy that may be at risk for serious birth disorders and may also be offered during the first trimester.

Blood Type and Rhesus Factor

At the first prenatal appointment, blood is taken that will establish maternal blood type, including the Rhesus (Rh) factor, which is a specific protein found on the surface of red blood cells. The blood type will be either A, B, AB or O, and the Rh factor will be either negative or positive, according to The American College of Obstetricians and Gynecologists. If the blood has the Rh antigen, it will be Rh positive; if it does not have the antigen, it will be Rh negative.

Diabetes and Anemia

A raised level of blood glucose found during a routine early pregnancy blood test may be a sign of gestational diabetes. Further tests would then be needed, which would involve drinking a special mixture and another blood test to diagnose diabetes, according to The American College of Obstetricians and Gynecologists. Blood is also tested for hematocrit and hemoglobin levels; low levels may signify anemia and can be treated with iron supplements.

Disease Exposure

Early blood tests will determine whether a pregnant woman has had exposure to infectious diseases such as rubella (German measles), mumps, hepatitis B (a virus that affects the liver), syphilis, HIV (the virus that causes AIDS) and possibly toxoplasmosis. These diseases can cause a major threat to the health of mother and fetus, but treatments are available during the pregnancy and postpartum period to reduce the risk of harm, according to The American College of Obstetricians and Gynecologists.

Fetal Screening

An optional blood test offered between weeks 11 and 13, helps assess the risk of a pregnancy affected by a serious birth disorder, such as Down syndrome or trisomy 18, according to the March of Dimes. The blood is tested for levels of two substances; hCG and pregnancy-associated plasma protein A. The result of this blood test and a detailed ultrasound scan, which measures the thickness at the back of the fetal neck, determines the risk of a birth disorder but does not diagnose a condition.

Genetic Testing

Optional genetic testing may be offered to those pregnant women at risk of genetic disorders such as cystic fibrosis, sickle cell anemia, Tay-Sachs disease and Canavan disease, according to the American College of Obstetricians and Gynecologists. Those considered at risk could be women from certain ethnic backgrounds or those with a family history of the disease. If the mother or father is found to be a carrier of a genetic disease, they may pass the disease on to their child.

References

• Mayo Clinic- First Trimester Screening
• Mayo Clinic- Prenatal Care
• The American College of Obstetricians and Gynecologists

Resources

• What to Expect.com