First trimester blood tests (booking visit, 8–12 weeks)
| Test | Purpose |
|---|---|
| Blood group (ABO) and Rh type | Identify Rh-negative mothers who need anti-D injections to prevent haemolytic disease of the newborn |
| Full Blood Count (FBC) | Detect anaemia early in pregnancy — haemoglobin target ≥11 g/dL in 1st trimester |
| Ferritin / iron studies | Iron deficiency is the most common pregnancy anaemia — treat before anaemia develops |
| Rubella antibody (IgG) | Confirm immunity — rubella in pregnancy causes serious birth defects |
| Syphilis (RPR/VDRL) | Congenital syphilis is preventable — treatment in pregnancy is curative |
| Hepatitis B (HBsAg) | Babies of HBsAg-positive mothers need vaccination + HBIG at birth |
| HIV | Treatment in pregnancy reduces mother-to-child transmission to <1% |
| TSH (Thyroid) | Hypothyroidism in pregnancy risks miscarriage and baby's brain development |
| Blood pressure + urine protein | Baseline for pre-eclampsia monitoring |
Second trimester blood tests (15–20 weeks)
Down syndrome and chromosome screening
The combined first trimester screening (10–14 weeks) uses nuchal translucency ultrasound + PAPP-A + free beta-hCG to assess chromosomal risk. The second trimester quadruple screen (15–20 weeks) uses AFP, hCG, estriol and inhibin-A. Non-invasive prenatal testing (NIPT) — a blood test using cell-free fetal DNA — can screen for Down syndrome from 10 weeks with >99% sensitivity. Abnormal results require confirmatory amniocentesis or chorionic villus sampling.
Third trimester blood tests (24–36 weeks)
| Test | When | Purpose |
|---|---|---|
| Gestational diabetes (OGTT) | 24–28 weeks | 75g oral glucose tolerance test — GDM affects 5–10% of pregnancies |
| FBC (repeat) | 28 weeks | Iron deficiency anaemia worsens as pregnancy progresses |
| Antibody screen (repeat) | 28 weeks | Check for red cell antibodies in Rh-negative mothers |
| Group B Streptococcus (GBS) | 35–37 weeks | Vaginal swab — GBS in baby can cause serious neonatal infection |
Questions to ask your midwife or obstetrician
- Am I Rh-negative — do I need anti-D injections?
- Is my iron level good — should I take iron supplements?
- What are my gestational diabetes screening results?
- Has my NIPT or chromosome screening been completed?
- What is my thyroid result — do I need treatment?
Medical Disclaimer: For educational purposes only. Always consult a qualified healthcare professional for diagnosis and treatment.