Laboratory Testing

Your OB’s office will refer you to a regional or hospital laboratory for your pregnancy laboratory work. There many national and local laboratories such as the following laboratories available in the author’s area:

  • Quest laboratory nationally
  • LabCorp
  • SmithKline
  • Your local hospital laboratory

Here are a series of Standard laboratory testing during your pregnancy as follows per ACOG guidelines:

Table 1-1 of Standard Pregnancy Laboratory Testing

Weeks 1-13

CBC, RPR, Blood type and Rh, Antibody Screen, TSH with or without reflex T4, Rubella immunity, HIV, Hepatitis B, Sickle Cell (if Afro-American heritage), Cystic Fibrosis, Chlamydia, Gonorrhea, Pap and reflex HPV, and Drug testing, Maternal Genetic Testing (as indicated)

Week 16-20

Multiple Marker screen for neural tube defects, GI defects and Down’s syndrome

NIPS (Non-invasive prenatal screening: Harmony®, Materna 21® and Panorama

Week 28-32

Anemia and 1 hour 50 grams Glucose (Gestational Diabetes test)

Week 36

Group B Strep Testing (GBS, not GPS!) and Repeat Hemoglobin (anemia check)

Table 1-2 Table of Extended Genetic and Physical Testing



* 3 hour Glucose Tolerance Test performed if 1 hour glucose>130 mg%
**Anemia studies and Glucose Tolerance are done at any time during pregnancy as indicated

In 2013, Laboratory Services and other Laboratories have introduced new antenatal blood tests, NIPS or Non-invasive Prenatal Screening (commercially branded as MaterniT21Plus, Harmony, Panorama, etc.) that can screen for Trisomy 21 (Down’s syndrome), Trisomy 13, and Trisomy 18 starting around 11 weeks of pregnancy. Further these tests can reveal the sex of your baby. Your blood is drawn (maternal blood) and the laboratory checks your blood for the baby’s blood hemoglobin that has crossed into your circulation. This blood test can be done as early as the 10th week of pregnancy. Because this test can make an extremely early diagnosis of some chromosomal defects, parents can be made aware of the baby’s condition and decide earlier in the pregnancy on the various options and treatments that are available to them.

One important caveat: if there is less than 3.5% of fetal hemoglobin in the patient’s blood sample, these tests may not be able to produce any results. Further, if you weigh over 160 lbs. this type of testing may return showing “not enough fetal Hemoglobin extraction for testing. The testing may have to be postponed until the time window between 16 to 20 weeks.

These tests may take up to 2 weeks before a report is available. Accordingly, other screening tests and anatomy ultrasounds will continue to have a place in the antenatal diagnosis of fetal abnormalities.


During these times of rapid technological advances OB’s will continue to perform “Anatomy Ultrasounds” for physical defects that are not genetically related.

Multiple Marker screening on maternal blood is performed at 18 to 20 weeks to help diagnose chromosomal abnormalities. Also, during this window of time in pregnancy ultrasound can screen for physical defects as well as the sex of the baby. If an abnormality is found on these latter two tests (ultrasound and Multiple Markers) then maternal blood sampling for Fetal DNA (NIPS testing) can be performed to make a more clear diagnosis. Most OB’s are moving away from the more invasive testing, i.e., amniocentesis and CVS, particularly if the targeted ultrasound study is normal. Obviously, invasive testing carries increased risks to the pregnancy such as rupture of the amniotic sac, infection, bleeding, etc. Very rarely, the pregnancy can be lost due to complications of these more invasive procedures (1:350 approximately).