Lab tests

At your first prenatal visit, blood tests might be done to:

• Check your blood type. This includes your Rh status. Rh factor is an inherited trait that refers to a protein found on the surface of red blood cells. Your pregnancy might need special care if you're Rh negative and your baby's father is Rh positive.
• Measure your hemoglobin. Hemoglobin is an iron-rich protein found in red blood cells that allows the cells to carry oxygen from your lungs to other parts of your body. Hemoglobin also carries carbon dioxide from other parts of your body to your lungs so that it can be exhaled. Low hemoglobin or a low level of red blood cells is a sign of anemia. Anemia can make you feel very tired, and it may affect your pregnancy.
• Check immunity to certain infections. This typically includes rubella and chickenpox (varicella) — unless proof of vaccination or natural immunity is documented in your medical history.
• Detect exposure to other infections. Your health care provider will suggest blood tests to detect infections such as hepatitis B, syphilis, gonorrhea, chlamydia and HIV, the virus that causes AIDS. A urine sample might also be tested for signs of a bladder or urinary tract infection.