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Your First Trimester: What Tests to Expect and What They Mean

Positive pregnancy test in hand? Wiped out just by getting up from the couch? Mapping out the best places to discretely puke while at the office? Congratulations, and welcome to the first trimester!

Assuming you’ve had your first prenatal visit and seen that galloping heartbeat, you’re ready for the next step—testing. So much testing.

You’ll pee into a cup (many times), get your blood drawn (a few times), and have a total stranger check out your baby with an ultrasound.  Here is a schedule of all the tests you may have over the next nine months:

first trimester test


These tests fall into two broad categories:

  • standard health check for you or baby (blood work, urine tests, blood pressure, gestational diabetes screening, ultrasounds)
  • prenatal genetic testing (first trimester screening, NIPT, chorionic villus sampling, amniocentesis)

The first set are standard procedure, but they may require some additional doctor and lab visits. For prenatal genetic testing, you will have options and decisions to make especially in the first trimester. To skip ahead to our section on first trimester prenatal genetic testing, click HERE.

First Trimester Blood & Urine Tests:

Complete Blood Count (CBC)

Assesses different cell counts in your blood. Low red blood cell count may reflect anemia (low iron). White blood cells can indicate how your body will handle illness. And platelet number can show whether you are at risk for blood clotting problems.

Blood Type

Determines whether you are Rh positive or negative. Rh factor is a protein marker on your red blood cells. If you are Rh negative and baby is Rh positive, your body can make antibodies against Rh factor. This can cause problems with subsequent pregnancies. To prevent antibody production, you will receive a shot around 27 weeks.


Determines if you have previously been infected or have been immunized against Rubella. Becoming sick with Rubella (German measles) during pregnancy can cause serious birth defects.

Hepatitis B (and maybe C)

These viruses can pass through the placenta to your baby. This tests sees whether or not you are infected.


Yup, you’ll be checked for Syphilis and Chlamydia since without proper treatment these sexually transmitted infections can lead to complications for you and your baby. Isn’t pregnancy fun? Read more about these tests HERE.


Checks for red blood cells that may indicate a urinary tract disease, white blood cells that could indicate a urinary tract infections, glucose (an early indicator of gestational diabetes), and protein to compare to later protein tests for preeclampsia.

Urine Culture

Assesses your urine for the presence bacteria, which can indicate a urinary tract infection (UTI).

Prenatal Genetic Testing: First Trimester Screening, NIPT, and Diagnostic Testing

Deciding what, if any, prenatal genetic testing you want can be daunting. There are lots of choices. And no one can or should dictate the best option for you.

We are not here to try. But what we firmly believe is that the risks and benefits of each option can—and should—be made easy to understand.

Below we summarize the pros and cons of your first trimester genetic testing options.

(For those who want more data (yes, give me more data!), check out our e-book, The Complete Guide to Prenatal Testing, where we delve deeply into the science, history, and numbers.)

First Trimester Screening

The first trimester screening, performed between 11 and 13 weeks, is the first part of the combined screen. (The second part happens between weeks 16-18). It provides a risk estimate of how likely your baby is to have Trisomy 21 (Down Syndrome), Trisomy 18, or Trisomy 13.


The first trimester screening includes blood work and a detailed ultrasound between weeks 11-13.


Your risk estimate is based on:

  • Your age
  • Your baby’s fetal nuchal translucency (NT) – an ultrasound measurement of the amount of fluid in the back of your baby’s neck
  • The levels of two pregnancy hormones in your blood: free β-human chorionic gonadotrophin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A). 

Results usually return within a week and contain two pieces of information: a risk estimate and whether that estimate is considered “positive” or “negative” for any of the three trisomies. Whether your risk estimate is considered “positive” or “negative” is based on an arbitrary cut-off. A risk of 1 in 250 or higher is typically considered positive and an indication for further testing.

See our Complete Guide to Prenatal Testing ebook for more details on the pros and cons of first trimester screening.

Non-invasive prenatal testing (NIPT)

Non-invasive prenatal testing (NIPT) , also called non-invasive prenatal screening (NIPS), is another option for genetic screening that requires only a simple blood draw. NIPT works by analyzing small DNA fragments known as cell-free DNA. These fragments pass from your baby’s placenta into your bloodstream. 

NIPT has lots to recommend it. Compared to traditional first trimester screening, NIPT has a much higher detection rate and lower false positive rate for the three most common genetic abnormalities (Trisomy 21, 13, and 18). It does not increase your chances of miscarriage. It can be done as early as 10 weeks. And, in addition to testing for genetic disorders, it can tell you your baby’s sex with greater than 99% accuracy [9]


Compared to traditional first trimester screening, NIPT has a much higher detection rate and lower false positive rate for the three most common genetic abnormalities.


Although highly accurate, NIPT is a screening test, since it provides a risk estimate, not a diagnosis. Risk estimates higher than a predetermined cutoff, usually 1 in 100, are reported as positive

What disorders does NIPT screen for? All NIPT tests can detect Down Syndrome, Trisomy 18, and Trisomy 13. Upon request. They can also test for sex chromosome abnormalities, including monosomy X (Turner Syndrome), XXY (Klinefelter’s Syndrome), and XXX (Triple X). Some will also cover a few rare chromosomal abnormalities upon request.

See The Complete Guide to Prenatal Testing for more details on the pros and cons of NIPT.

Chorionic villus sampling

Diagnostic testing like chorionic villus sampling and amniocentesis are the only tests that can, as their name implies, diagnose genetic disorders. These diagnostic tests give a yes or no answer to whether your baby has a particular genetic disorder.

Chorionic villus sampling (CVS) is the only diagnostic test available in your first trimester. Doctors usually perform CVS between 10 and 13 weeks of pregnancy. (Amniocentesis is usually done a bit later, between 16 and 18 weeks of pregnancy.)

During CVS, a doctor inserts a needle into finger-like projections of the placenta known as “villi”. The doctor will then pull out some of these cells for testing. An ultrasound is used to guide the needle. This helps your doctor avoid contact with your baby. After extraction, your doctor will send the placental cells to a laboratory to be analyzed.


Diagnostic tests are the only genetic tests that can tell you for certain whether your baby has a particular genetic disorder.


You can expect your results within a week.

Diagnostic tests like CVS have two major benefits:

  1. They can tell you for certain whether your baby has or does not have a particular genetic disorder. (By contrast, screens tell you how likely your baby is to have a genetic problem.)
  2. They test for a wider range of genetic disorders than any of the available screens. 

Read more about the pros and cons of chorionic villus sampling and amniocentesis HERE.

Looking for more info? 

Our free (yes, free!) ebook, The Complete Guide to Prenatal Testing covers nearly everything you could possibly want to know about prenatal genetic testing. Check it out!

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About Amy

Amy Kiefer is a researcher by training, and earned her Ph.D. from the University of Michigan. She currently lives in the Bay Area with her husband and three children where she writes about fertility, pregnancy, and breastfeeding. Check out her blog,, for more great evidence-based pregnancy and parenting info.


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