Blood Tests in Pregnancy: Complete Guide
Blood tests are a routine and important part of NHS antenatal care, helping your midwifery team check your health, screen for a small number of conditions, and plan the right care for you and your baby throughout pregnancy. Here's what's tested and when.
Blood tests at your booking appointment
Your booking appointment, usually around 8 to 12 weeks, is when most of your initial blood tests are taken in one go.
- Blood group and rhesus (Rh) factor — this tells your team whether you're Rh-negative, which affects whether you'll need anti-D injections later in pregnancy.
- Full blood count — checks for anaemia and other blood conditions that could affect your pregnancy or delivery.
- Haemoglobinopathy screening — checks for sickle cell disease and thalassaemia, inherited blood conditions that can affect your baby.
- Infectious disease screening — tests for HIV, syphilis, and hepatitis B, all of which can be managed effectively during pregnancy if identified early, protecting both you and your baby.
- Rubella immunity — in some areas this is still checked to confirm you're protected against rubella (German measles), which can seriously affect a developing baby if caught in early pregnancy.
Blood tests later in pregnancy
Further blood tests are offered at set points as your pregnancy progresses.
- Combined screening bloods (11–14 weeks) — measure hCG and PAPP-A, two pregnancy-related proteins used alongside the nuchal translucency scan measurement to calculate the chance of certain chromosomal conditions.
- Repeat full blood count (around 28 weeks) — rechecks for anaemia, which becomes more common as pregnancy progresses and your blood volume increases.
- Anti-D (around 28 weeks, if you're Rh-negative) — a preventive injection rather than a test itself, but it follows from your earlier blood group result.
- Glucose tolerance test (24–28 weeks) — offered if you have risk factors for gestational diabetes, such as a higher BMI, a family history, or a previous large baby.
Understanding your results
Most blood test results are straightforward and simply confirm everything is progressing normally — you'll usually only hear back if something needs discussing further or if a follow-up test is recommended. Your midwife will talk you through anything relevant at your next appointment, and you can always ask them to explain a result if you're unsure what it means.
Frequently Asked Questions
Are pregnancy blood tests compulsory?
No, all antenatal blood tests are offered rather than compulsory, and you're entitled to decline any test you don't want. Most people choose to have the standard screening tests because they help your midwifery team plan safe, appropriate care, but the decision is always yours after discussing it with your midwife.
Do I need to fast before pregnancy blood tests?
Most routine antenatal blood tests don't require fasting, but the glucose tolerance test does — you'll usually be asked not to eat or drink anything except water for around 8 to 10 hours beforehand. Your midwife or the hospital will give you clear instructions in advance if a specific test requires fasting.
How will I get my blood test results?
Your midwife will usually share routine results at your next scheduled appointment, while anything requiring urgent follow-up is typically communicated sooner by phone or letter. If you're anxious about a result and haven't heard anything, it's fine to contact your midwife directly to check rather than wait and worry.
This article is for informational purposes only and does not constitute medical advice.
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