The Top Most Important Blood Tests to be done during Pregnancy
                     THE TOP MOST IMPORTANT BLOOD 
TESTS TO BE DONE DURING PREGNANCY
OBJECTIVE
• Right from the start of pregnancy, your 
gynecologist will recommend several 
blood tests with the objective of 
ascertaining you and your fetus’s 
health. 
• The tests are a vital part of your 
pregnancy journey, as it allows your 
doctor to come up with a personalized 
pregnancy care plan. 
• Also, problems or complications can be 
diagnosed early on with their help so 
that you and your baby get the right 
treatment on time. Here is a list of the 
most important blood tests offered 
during pregnancy, why they are required 
and when they should be done.
1. BLOOD GROUP: 
• This test determines your blood group, 
whether it is A, B, AB or O.
• Importance: In case a need for blood 
transfusion arises due to heavy 
bleeding during pregnancy or childbirth, 
knowing the blood group is vital.
• When: Done in the first trimester, 
usually in early pregnancy as a part of 
the first antenatal screening.
2. RH FACTOR: 
• Red blood cells have a surface protein called 
the Rhesus (Rh) factor. If present, you are Rh-
positive or else you are Rh-negative.
• Importance:  If you are Rh-positive, which is 
common, then there is no need to worry. But if 
you are Rh-negative and the baby is Rh-
positive, this can lead to Rh incompatibility. 
Your body can produce Rh antibodies against 
the baby’s blood cells. Although not an issue 
during the first pregnancy, these antibodies 
can attack the baby’s red blood cells in 
subsequent pregnancies, which can become 
life threatening to the baby. If tested in time, 
the Rh immune globulin injection can help to 
protect your baby.
• When: First trimester. If the mother is Rh-
negative, the test is repeated in the second 
trimester, at 28 weeks, to check for Rh 
antibodies.
3. COMPLETE BLOOD COUNT (CBC) AND 
OTHER ROUTINE BLOOD TESTS:
•Hemoglobin, hematocrit, Iron levels to check 
for anemia, information about blood cells, 
blood glucose to check for diabetes, lipid 
levels as well as thyroid gland functioning are 
measured.
•Importance: These tests diagnose anemia 
(which is common during pregnancy), 
diabetes, infection, and other disorders. 
Severe anemia can result in preterm birth or a 
low birth weight baby. On-time treatment and 
lifestyle changes can be done to ensure a 
healthy pregnancy.
•When: First trimester. Repeated in the second 
trimester around 26–28 weeks, mainly to 
check hemoglobin and platelet levels
4. SEXUALLY TRANSMITTED DISEASES 
AND OTHER INFECTIONS:
•Testing is done for Human Immunodeficiency 
Virus that causes AIDS, syphilis, herpes, 
hepatitis B and C, gonorrhea, Chlamydia and 
Rubella (German measles) antibodies.
•Importance: These infections can lead to 
severe complications for the baby, including 
birth defects. Early diagnosis and treatment 
can prevent transmission to the fetus.
•When: Done in the first trimester
5. HUMAN CHORIONIC GONADOTROPIN (HCG) 
HORMONE AND PREGNANCY-ASSOCIATED PLASMA 
PROTEIN SCREENING (PAPP-A):
• The tests measure hCG and PAPP-A, 
which are produced by the placenta 
during early pregnancy.
• Importance: Abnormal levels are 
associated with an increased risk of the 
fetus for chromosomal abnormalities like 
Down syndrome (trisomy 21) or Edwards 
syndrome (trisomy 18)
• When: Done in the first trimester
6. MULTIPLE MARKERS:
Depending on the number of markers 
screened, it is called Quad test (4 markers) 
or Triple test (3 markers). The following 
markers are tested:
 a) Alpha-fetoprotein (AFP): a protein 
made by the baby’s liver
b) Human chorionic gonadotropin 
(hCG): a hormone produced by the 
placenta
c) Estriol (uE3): a hormone made by both 
placenta and fetus
d) Hormone inhibin A: produced by the 
fetus and the placenta
6. MULTIPLE MARKERS:
• Importance: These tests screen for certain 
substances in the blood that determine the 
risk for genetic conditions or defects in the 
baby such as Down syndrome, spina bifida, 
or anencephaly. They are not diagnostic or 
completely accurate. Hence, they are 
considered along with the mother’s age, 
health history, ethnicity and other factors 
to determine a more than average chance 
of the baby having a birth defect. In case of 
abnormal results, additional testing such 
ultrasound and an amniocentesis are done 
for an accurate diagnosis.
• When: Between 15 and 20 weeks of 
pregnancy, although 16-18 weeks is ideal
7. ORAL GLUCOSE TOLERANCE TEST: 
• This test measures the blood glucose level to 
check for diabetes that occurs during 
pregnancy, known as gestational diabetes. It 
usually goes away after childbirth. Initially, a 1-
hour glucose tolerance test is done, which, if 
abnormal, is followed by a 3-hour glucose 
tolerance test.
• Importance: Gestational diabetes can give rise 
to severe complications like pre-eclampsia and 
infection. Treatment can ensure healthy 
childbirth.
• When: Between 24 and 28 weeks of pregnancy
CONCLUSION
• Thus, these most important blood 
tests done during pregnancy check 
for a wide range of conditions and 
also give a fair idea about your 
unborn baby’s health. Depending on 
your ethnic background and family 
history, your doctor might 
recommend other prenatal tests.
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REFERENCES
• https://www.cordlifeindia.com/blog/top-important-blood-tests-don
e-pregnancy/
• http://acog.org/patient-resources/faqs/pregnancy/routine-tests-
during-pregnancy
• http://ncbi.nlm.nih.gov/books
• http://hopkinsmedicine.org/health/wellness-and-
prevention/common-tests-during-pregnancy