Medical Tests in the First Trimester

If you’re expecting a baby, expect to undergo a variety of medical tests during pregnancy. These are done to check for potential health problems that could affect you or the baby developing in your womb. Some are only necessary if there is a risk of genetic conditions or birth defects.

Here’s a look at some common prenatal tests and when they might be conducted during the first trimester of pregnancy:

  • Blood Type and Rh Factor Test – A simple blood test, typically done during your first prenatal care visit, will let your healthcare provider know your blood type and Rh factor. The Rh factor—a protein found on red blood cells in most people—is important in pregnancy. If you have don’t have this protein, but your fetus does, it can cause health problems in your baby. Learn more about this and how any resulting problems are treated.
  • Noninvasive Prenatal Screening – A test of your blood to check your baby’s DNA for certain genetic conditions, including Down syndrome. Recommended if you had an earlier pregnancy involving birth defects or after abnormal first trimester screening results (see below). NOT recommended if there’s no risk of birth defects or if you’re pregnant with multiples. Typically given after 10 weeks.
  • First Trimester Screening – A blood test and an ultrasound to check for possible birth defects, such as Down syndrome and heart defects. At 11–13 weeks of pregnancy.
  • Chorionic villus sampling (CVS) – Tiny tissue samples from your placenta are extracted by a needle inserted through your abdominal wall or by a thin tube (catheter) inserted vaginally up through your cervix. The samples, which have the same genetic makeup as your baby, are then tested for genetic abnormalities, such as Down syndrome. At 10–12 weeks.

    CVS is an invasive procedure with a small risk of infection or miscarriage. The test is only recommended if your baby has a higher risk of birth defects because you:
    • Are 35 or older
    • Tested positive in a noninvasive prenatal screening test
    • Had an ultrasound that indicated possible abnormalities
    • Had a previous pregnancy involving a genetic condition (such as Down syndrome)
    • Have a family history of a specific genetic condition
  • Carrier screening – These tests, which can be done anytime in pregnancy (or before), look at whether you or your partner carry a gene for certain inherited disorders, called recessive disorders. Each parent needs to carry a gene for the particular recessive disorder (though not necessarily be affected by it) in order for the baby to have the disorder. These recessive disorders include cystic fibrosis, spinal muscular atrophy, sickle cell disease and other.

Learn more about carrier screening and how to interpret the findings.

Tests in the second and third trimesters.

This message is not intended to provide individual medical advice. Always seek the advice of a physician or qualified healthcare provider for any questions you have about your health or medical condition, your breastfeeding issues and your infant's health. Never disregard, avoid or delay contacting a doctor or other qualified professional because of something you have read in our emails, webpages or other electronic communications.

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