Pregnancy Tests by Trimester: What Is Checked and When

Pregnancy involves many tests, and the list can be daunting. In fact each one has a purpose — to watch the mother's health and the baby's development and catch risks in time. Let's go through what tests are done in pregnancy by trimester and why. For an overview of all stages, see pregnancy week by week. The exact list is set by the doctor managing the pregnancy — it depends on gestation, history and protocol.

First Trimester Pregnancy Tests (Up to 13–14 Weeks)

The baseline "intake" set at booking:

• Complete blood count — haemoglobin, detecting anaemia; the trimester breakdown is in CBC in pregnancy.
• Blood biochemistry and fasting glucose.
• Blood group and rhesus factor (and the partner's) — important to prevent rhesus conflict.
• Infections: HIV, hepatitis B and C, syphilis, TORCH as indicated.
• Urinalysis (at every visit).
• hCG and the first screening (ultrasound + biochemistry) at 11–14 weeks; on the hormone's role — hCG.

Second Trimester Pregnancy Tests (14–27 Weeks)

• Repeat CBC and urine, monitoring haemoglobin and ferritin (see anaemia in pregnancy).
• Glucose tolerance test (GTT) at 24–28 weeks — gestational diabetes screening; more in gestational diabetes.
• Second screening (ultrasound) — fetal anatomy.

Third Trimester Pregnancy Tests (28+ Weeks)

• Repeat CBC, urine, biochemistry, coagulation as indicated.
• Repeat infection tests (HIV, hepatitis, syphilis) before delivery.
• Third ultrasound screening and assessment of the fetus.

Why So Many Pregnancy Tests and What Results Mean

Pregnancy tests are not "over-caution" but early detection of anaemia, diabetes, infections and rhesus conflict, which are easier to treat the earlier they are caught. Many norms in pregnancy are shifted (for example haemoglobin is lower, ESR higher — this is physiological), so results are read against "pregnancy" references, not the usual ones.

When a Result Needs Attention

Tell your doctor about marked anaemia, high sugar, protein in urine with swelling and high blood pressure (pre-eclampsia risk), and positive infection tests. Early signs and confirmation of pregnancy are in first signs of pregnancy.

To understand your own form in plain language, upload the test (PDF or photo) to the lab results interpretation service: the AI will explain the markers against the norms. This helps you understand the result but does not replace your obstetrician.

This article is informational. Pregnancy management and test interpretation are the doctor's job.