Blood tests during pregnancy

You’ll have several blood tests through your pregnancy, and while nobody loves a needle, each one gives your care team useful information to keep you and your baby well. Knowing roughly what they’re checking — and when — takes the mystery out of it.

Your first (booking) blood tests. Early in pregnancy, usually at your first proper appointment, you’ll have a set of tests that cover a lot of ground:

• Blood group and Rh (rhesus) status — whether you’re Rh-positive or Rh-negative, which matters for your care later (there’s a separate article on Rh-negative blood).
• Full blood count — including your haemoglobin, to check for anaemia (low iron is common in pregnancy), and your platelets.
• Antibody screen — checking for antibodies that could affect your baby.
• Immunity to infections like rubella (German measles) and chickenpox (varicella), so you know whether you’re protected.
• Screening for infections such as hepatitis B and C, syphilis and HIV — these are routine, and finding any of them means steps can be taken to protect your baby.
• Depending on your background and risk factors, tests for things like thyroid function, vitamin D, and iron studies may be included.

If you’re having first-trimester screening (like the combined screening or NIPT), that involves a blood test too.

Later in pregnancy. A few more tests are timed for later:

• The glucose test for gestational diabetes, usually between 24 and 28 weeks — often the oral glucose tolerance test (OGTT), which means fasting overnight, a sugary drink, and blood taken over a couple of hours.
• A repeat full blood count to check your iron/haemoglobin again, as anaemia can develop as pregnancy goes on.
• A repeat antibody screen, particularly if you’re Rh-negative.

Your care team may order others along the way if anything needs checking — for example, if you have symptoms, a specific condition, or a result they want to follow up.

What the tests are like. Most are a standard blood draw from your arm, and you can usually just turn up at a pathology collection centre with your request form (many bulk-bill for pregnancy tests, so it’s often free). The main one that needs preparation is the glucose tolerance test, which requires fasting beforehand — your provider will tell you exactly how. If needles make you queasy or faint, tell the person taking your blood so you can lie down; it’s common and they’re used to it.

Getting your results. Results go back to whoever ordered them — your GP, midwife or obstetrician — who’ll discuss anything that needs action with you. No news is usually good news, but it’s always fine to ask at your next appointment what your results showed, including your iron levels and blood group, so you understand your own care.

If a result needs follow-up. Sometimes a test flags something — low iron, low immunity to rubella, or an infection, for example. Try not to worry before you’ve spoken to your provider: many results simply lead to a straightforward next step, like an iron supplement, a vaccine after the birth, or extra monitoring. That’s exactly what the testing is for — picking things up early so they can be managed.

A few results explained. If your iron or haemoglobin is low, you’ll likely be advised to take an iron supplement — very common and easily managed. If you’re found not immune to rubella or chickenpox, you can’t have those vaccines during pregnancy (they’re “live”), but you’ll be offered them after the birth to protect future pregnancies. If you’re Rh-negative, Anti-D injections become part of your care. And if screening for an infection is positive, it simply means steps are taken to protect your baby — which is the whole point of testing.

Genetic carrier screening is another blood test you may be offered, ideally before or early in pregnancy. It checks whether you and your partner carry genes for certain inherited conditions like cystic fibrosis or spinal muscular atrophy. It’s optional and usually has an out-of-pocket cost, and your GP can explain whether it’s something you’d like to consider.

If you’re not a fan of needles, you’re far from alone, and pregnancy involves a few. Tell the person taking your blood if you feel faint or anxious — they can have you lie down, and it’s completely routine for them. Staying hydrated makes the draw easier, looking away and breathing slowly helps, and it’s over quickly. If you’ve fainted with blood tests before, mention it every time.

It’s a lot of blood tests over nine months, but each is a small, routine part of good antenatal care. If you’re ever unsure why a particular test is being done or what a result means, ask your midwife or GP — understanding your own results is your right, and no question about your own care and body is ever too small for them to explain.