Which blood tests happen in the second trimester?

In the second trimester, antenatal care commonly includes Hemoglobin, TSH, Free T4 (FT4), Fasting Glucose, OGTT, Ferritin, among others. The exact tests and timing are decided by your obstetrician [WHO, 2016].

Are the reference ranges different in the second trimester?

For some tests, yes — thyroid and glucose in particular are read against pregnancy- or trimester-specific ranges [ATA, 2017]. Each test page names its source where trimester-specific data exists.

What should I do with a result in the second trimester?

Bring the full report to your obstetrician, who interprets each value for your specific pregnancy. Antenatal results are always discussed with them rather than acted on alone.

Why are anaemia and gestational diabetes checked in pregnancy?

They are common and manageable, and antenatal testing is designed to catch them early so your obstetrician can guide next steps.

Second trimester — antenatal tests

Informational only. Antenatal results should always be discussed with your obstetrician, who interprets them for your specific pregnancy.

Blood tests typically done in the Second trimester of pregnancy.

Last reviewed: 2026-08-16

Second trimester — antenatal tests

HemoglobinHemoglobin measures the protein in red blood cells that carries oxygen. It supplies oxygen to your body and to your baby.
TSHTSH (Thyroid-Stimulating Hormone) is a hormone from the pituitary gland in your brain. It controls how much thyroid hormone your thyroid gland makes.
Free T4 (FT4)Free T4 is the active, unbound form of thyroxine. Thyroxine is the main hormone your thyroid gland makes.
Fasting GlucoseFasting glucose measures the sugar in your blood. It is taken after an overnight fast of at least 8 hours.
OGTTThe oral glucose tolerance test (OGTT) shows how your body handles a standard glucose drink. Your blood sugar is checked while fasting, then at 1 hour and 2 hours.
FerritinFerritin is a protein that stores iron in your cells and tissues. Its blood level reflects the total iron reserves in your body.
Vitamin DThis is the vitamin D test. It measures 25-hydroxyvitamin D (25-OH Vitamin D) in your blood. This is the main form in your blood. It reflects your overall vitamin D stores.
Vitamin B12Vitamin B12 is a nutrient your body needs for nerves, red blood cells, and DNA. The vitamin B12 test measures its level in your blood.
Platelet CountPlatelet count measures the number of tiny blood cells called platelets. Platelets help your blood clot and stop bleeding.
Urine Routine & ProteinThe urine routine examination checks a urine sample for protein, glucose, blood, white cells, and other parts. The protein check looks at whether your kidneys are leaking protein.
Double / Triple / Quadruple MarkerThese are blood tests that measure certain proteins and hormones from the placenta and baby. The results are combined with your age, weight, and pregnancy stage. Together they give a risk estimate as a number.

Tests by trimester

Frequently asked questions

Which blood tests happen in the second trimester?: In the second trimester, antenatal care commonly includes Hemoglobin, TSH, Free T4 (FT4), Fasting Glucose, OGTT, Ferritin, among others. The exact tests and timing are decided by your obstetrician [WHO, 2016].
Are the reference ranges different in the second trimester?: For some tests, yes — thyroid and glucose in particular are read against pregnancy- or trimester-specific ranges [ATA, 2017]. Each test page names its source where trimester-specific data exists.
What should I do with a result in the second trimester?: Bring the full report to your obstetrician, who interprets each value for your specific pregnancy. Antenatal results are always discussed with them rather than acted on alone.
Why are anaemia and gestational diabetes checked in pregnancy?: They are common and manageable, and antenatal testing is designed to catch them early so your obstetrician can guide next steps.