During the first trimester, your healthcare provider will present you with many options for medical and genetic testing. All pregnant people should have their blood drawn and urine tested for a basic medical check-in, but many people will also opt for further genetic testing. Typical medical tests ordered during the first trimester include the following, although not everyone will need or choose all of these options.
Blood tests
At the very first prenatal appointment, a healthcare provider will usually have blood drawn and tested for blood type and RH factor, a complete blood cell count, Hepatitis B, HIV, Rh-factor, syphilis and rubella. The provider will do this to ensure there is no disease or deficiency that could affect a pregnancy. Almost everyone will have their blood tested around the time of the first prenatal visit.
Urine tests
Urine tests are a staple of most prenatal appointments. The healthcare provider checks urine for elevated levels of protein or sugar, both of which can indicate serious pregnancy-related conditions like preeclampsia or gestational diabetes. Your first urine sample is also checked for any signs of infection. If you experience urinary symptoms like pain or burning, let your provider know, and this can easily be checked again.
Cell-free fetal DNA testing
This type of screening test goes by many different brand names, and it is incredibly popular. As early as weeks 8-9, this test provides screening for a variety of chromosomal differences (and sex) with a small maternal blood sample. The screening analyzes small pieces of fetal cells in your blood to determine if your unborn baby might have a higher risk than others of any chromosomal abnormalities. This test is a great way to look for the possibility of chromosomal differences, but confirmation of a positive screening requires invasive tests like CVS or, later on, amniocentesis. There is the possibility of false positives or negatives with any screening test
Chorionic villus sampling
Chorionic villus sampling (CVS) is an invasive diagnostic procedure that can help find chromosomal differences in your pregnancy. Unlike cell-free DNA screening, CVS is considered diagnostic. Although it is more invasive, it gives a clearer picture of certain conditions. It is a short, in-office procedure that can be done as early as 10 weeks gestation, although results may take a few weeks to process. There is a small increased risk of miscarriage after CVS testing.
First trimester combined screen
The First Trimester Combined Screen, performed between weeks 11 and 14 of pregnancy, is another older genetic testing option that consists of a maternal blood sample and a Nuchal Translucency (NT) ultrasound examination.
The blood sample tests for abnormal levels of specific chemicals which can indicate chromosomal difference. In addition, the NT ultrasound is performed to determine the size of clear space (fluid) in the back of the unborn baby’s neck, which can indicate a risk of Trisomy 21 (Down syndrome) or other developmental conditions. It also looks at the developing nasal bone. The First Trimester Combined Screen is not diagnostic, and like cell-free DNA, it screens for an increased likelihood of having certain chromosomal disorders.
Sources
- Amy Swanson, Amy J. Sehnert, Sucheta Bhatt. “Non-invasive Prenatal Testing: Technologies, Clinical Assays and Implementation Strategies for Women’s Healthcare Practitioners.” Curr Genet Med Rep. 1(2): 113-121. Web. 6/13/2015.
- Mayo Clinic Staff. “Prenatal care: 1st trimester visits.” Mayo Clinic. Mayo Clinic, 7/31/2015. Web.
- “Prenatal care in your first trimester.” U.S National Library of Medicine. MedlinePlus, 6/11/2014. Web.
- “Prenatal tests.” March of Dimes. March of Dimes, 6/3/2016. Web.
- Mayo Clinic Staff. “Chorionic Villus Sampling.” Mayo Clinic. Mayo Clinic, 10/17/2015. Web.
- Mayo Clinic Staff. “Noninvasive prenatal testing.” Mayo Clinic. Mayo Clinic, 2/23/2013. Web.
