According to the Palo Alto Medical Foundation, the first trimester of pregnancy consists of the 13 weeks after your last menstrual period. Typically, your first prenatal visit will occur between the 8th and 10th week of pregnancy to start your prenatal care. Various tests and screenings are done throughout the trimesters of pregnancy, each at a specific trimester, to evaluate the development and health of the fetus and mother.
Initial General Screening
When you initially go to your obstetrician, your provider will get a full history from you and do a complete physical exam, including taking your weight, blood pressure and a urine specimen and giving you a pelvic exam, according to the Palo Alto Medical Foundation. General blood work is typically done, including a complete blood count, blood type and Rh factor testing, HIV and Hepatitis B screening and syphilis testing. You may need to give consent for the HIV testing.
Genetic Testing
Some types of screening may be done to see if you or your partner are carriers for any genetic diseases. Tests can include those for cystic fibrosis, sickle cell anemia, thalassemia, Tay-Sachs and Canavan disease. Talking to your provider can help you go over the risks and benefits of screening for various diseases and what each one means for your fetus.
Chorionic Villus Sampling (CVS) is typically done between 10 and 13 weeks of pregnancy, and it looks for genetic disorders and chromosome abnormalities, according to the American Pregnancy Association. CVS consists of placing an ultrasound-guided needle or catheter through the abdomen to the placenta to take a sample of tissue. It can be done earlier in the pregnancy than amniocentesis but does not test for neural tube defects like amniocentesis does. There is a risk of miscarriage with this test, approximately 1 in 100.
Ultrasound or Sonogram
During the first trimester, an ultrasound may be done to evaluate the size of the fetus to check its age and the positioning or location of the fetus. If vaginal bleeding occurs, an ultrasound can help determine the reason.
