Pregnancy Blood Tests by Trimester: What's Checked, When, and Why

Quick answer: In the first trimester, the antenatal profile usually includes CBC, blood group and Rh type, blood sugar, TSH, urine routine and culture, and screening for HIV, hepatitis B (HBsAg), syphilis (VDRL) and often hepatitis C and rubella immunity, plus thalassaemia screening (Hb electrophoresis) in India. The second trimester typically includes an OGTT for gestational diabetes at 24–28 weeks and a repeat CBC. The third trimester repeats CBC, urine and other tests as advised. Rh-negative mothers need antibody screening. Your obstetrician decides the exact schedule.

Pregnancy blood tests protect both mother and baby. They detect anaemia, thyroid problems, diabetes, infections that can pass to the baby, and blood group incompatibilities — all of which are manageable when found early.

Before Pregnancy (Pre-Conception)

If you're planning a pregnancy, a pre-conception check gives you time to correct problems:

• CBC and ferritin — see iron deficiency anaemia
• Blood group and Rh — see blood group testing
• TSH — see thyroid test
• HbA1c or fasting sugar
• Rubella immunity
• HIV, HBsAg, HCV, VDRL
• Thalassaemia screening for both partners — see pre-marital checkup
• Vitamin D and B12
• Folic acid supplementation — start before conception, as advised by your doctor

First Trimester (Up to 13 Weeks)

The Antenatal Profile

• CBC — anaemia is very common in Indian pregnancies; haemoglobin below 11 g/dL indicates anaemia
• Blood group and Rh type — if Rh-negative, an indirect Coombs test (antibody screen) is done, and your doctor will discuss anti-D
• Blood sugar — fasting, random or HbA1c, to detect pre-existing diabetes
• TSH — thyroid problems affect pregnancy and the baby's development; trimester-specific ranges are used
• Urine routine and culture — to detect infections, including those without symptoms
• HIV, HBsAg, VDRL — and often anti-HCV
• Rubella IgG — immunity
• Hb electrophoresis / HPLC — screens for thalassaemia trait, which is common in India

Screening Tests for the Baby

• First trimester combined screening (around 11–14 weeks): an ultrasound (NT scan) with blood markers (double marker — PAPP-A and free beta-hCG) to estimate the chance of chromosomal conditions
• NIPT (cell-free DNA testing) may be offered as an option — discuss with your doctor

Second Trimester (14–27 Weeks)

• OGTT (75 g) at 24–28 weeks to screen for gestational diabetes — earlier if you're at higher risk. See diabetes tests explained
• Quadruple marker if first-trimester screening wasn't done
• Repeat CBC
• Antibody screen for Rh-negative mothers, as advised
• Anomaly scan (around 18–20 weeks) — an ultrasound, done at imaging centres

Third Trimester (28 Weeks Onwards)

• Repeat CBC — anaemia often worsens in late pregnancy
• Urine routine — protein in urine can be a sign of pre-eclampsia (along with high BP)
• Blood sugar monitoring if gestational diabetes was diagnosed
• Repeat infection screening in some cases, as advised
• Coagulation and other tests before delivery, as your obstetrician decides

After Delivery

• CBC — to check for anaemia after blood loss
• OGTT 4–12 weeks after delivery if you had gestational diabetes, then regular sugar checks — your future diabetes risk is higher
• TSH if you had thyroid problems, or symptoms of postpartum thyroiditis
• Vitamin D, B12 and iron while breastfeeding, as advised

Tips for Pregnant Women Having Blood Tests

• Fast only when instructed (OGTT and fasting sugar)
• Carry your antenatal card and previous reports
• Tell the phlebotomist you are pregnant
• Consider home sample collection to avoid travel and waiting
• X-rays are generally avoided in pregnancy — always tell radiology staff you're pregnant

Frequently Asked Questions

What tests are included in an antenatal profile?

Usually CBC, blood group and Rh, blood sugar, TSH, urine routine, and screening for HIV, hepatitis B, syphilis, often hepatitis C, rubella immunity and thalassaemia.

When is the glucose tolerance test done in pregnancy?

The OGTT is usually done at 24–28 weeks, or earlier if you are at higher risk of gestational diabetes.

What is a normal haemoglobin in pregnancy?

Haemoglobin of 11 g/dL or above is generally considered normal in pregnancy. Below 11 g/dL indicates anaemia.

Why is thyroid tested in pregnancy?

Thyroid hormones are important for the baby's brain development and for a healthy pregnancy. Trimester-specific ranges are used.

What happens if I am Rh-negative?

Your doctor will order antibody screening and discuss anti-D injections to protect current and future pregnancies.

Can pregnancy blood tests be done at home in Gurugram?

Yes. Aarvak offers home sample collection for antenatal blood and urine tests across Sector 67, Sohna Road and nearby areas.

Book Pregnancy Tests in Gurugram

Bring your obstetrician's prescription and we'll take care of the rest — at our Sector 67 lab or at home. Call +91 92663 33711. See also essential tests for women.

This article is for general information only. Please follow your obstetrician's advice on testing during pregnancy.