Guide to blood tests during pregnancy

So you want to know how many blood tests during pregnancy to expect. Whether that’s because you’re simply curious, or you have a serious needle phobia to get past (deep breaths!), we can help you out here.

Some pregnant mamas will have more blood tests than others – i.e. if you run into complications, have a high-risk pregnancy, or get sick while you’re pregnant. (I strongly advise against getting gastro at 35 weeks, mmkay? It was not fun.) But there are some routine pregnancy blood tests we can safely say you’ll have done before you birth your baby.

So how often do you get blood tests during pregnancy?

At a minimum: You might have two in your first trimester and one in your second trimester, if your pregnancy all goes swimmingly.

From personal experience: Probably at least a few each trimester.

In this guide, we’re going to outline exactly what blood tests are done during pregnancy, and WTF you do if these tests come back with weird results. Let’s get into it.

Your routine pregnancy blood tests

First trimester pregnancy blood tests

Pregnancy test

But doesn’t that involve peeing on a stick? Yes, it can. While at-home pregnancy tests measure the level of human chorionic gonadotropin (hCG) in your urine, your doctor can also run a blood panel to see this.

Some women even find out they’re pregnant thanks to a pathology test while looking into other health issues. Surprise!

Full blood examination

You’ll likely have what’s called a ‘full blood examination’ at your first prenatal appointment, which could be at around weeks 6–8 depending on when you find out you’re pregnant. As it sounds, this is where doctors look at your blood in detail (ick!) to get an understanding of your overall health.

Your red blood cells, white blood cells, platelets and haemoglobin levels will provide important hints about how your early pregnancy is progressing and if you might run into complications. For example, developing preeclampsia (high blood pressure) or anaemia (low iron).

So what else to expect from what’s potentially your first blood test during pregnancy? First trimester blood work will also look at:

  • Your blood type – Important to know in case you need blood at any point during your pregnancy or birth.

  • Your Rh type – If you’re Rh-negative, you’ll be offered two injections of Anti-D during your pregnancy to reduce the risk of health problems for your baby. (This is because if their blood is Rh-positive your body might create antibodies that could be fatal for them. No thanks!)

  • Infectious diseases and antibodies – You’ll be tested for HIV, hepatitis B, hepatitis C, syphilis, and potentially other infectious diseases. Plus, your rubella and chickenpox immunity will be assessed because these can be nasty if you get them during pregnancy.

Nuchal translucency blood test

Your blood is generally taken as part of your combined first trimester screening test at around 12 weeks. This is a combo of a blood test and pregnancy ultrasound

The test looks for two types of proteins – PAPP-A (pregnancy associated plasma protein-A) and BhCG (beta human chorionic gonadotropin) – which can signal chromosomal abnormalities.

The ultrasound part of the screening involves your obstetrician looking at the fluid at the back of your baby’s neck, known as ‘nuchal translucency’. Excess fluid could also be a sign of a genetic condition like Down Syndrome. 

While the scan alone is generally quite enlightening, combining it with the blood test can increase detection from 80 per cent to 90 per cent according to Sydney Ultrasound for Women. Hence why these are generally performed at the same time and cross-referenced.

Genetic screening for carrier status

This is an optional blood test you can do at any stage of your pregnancy or beforehand. It will test your DNA for genetic markers that could indicate you’ll pass on a genetic disease to your child. Wild, right?! 

Keep in mind, screening for carrier status will only give you a likelihood of your baby having a condition. It’s not conclusive.

Second trimester pregnancy blood tests

Screening test for gestational diabetes 

This is one of the more vital blood tests during pregnancy. Second trimester gestational diabetes screening is important for picking up this condition, which around 10–20 per cent of women develop in pregnancy. While it often goes away after your baby is born (thank f*ck!), it needs to be carefully monitored and managed until then.

Between 24–28 weeks you’ll go in for a glucose tolerance test. This involves fasting overnight, then having some blood tests. You’ll have blood taken at the beginning, then be given a sugary drink to down in one. You’ll then have a blood test one hour after the drink, and another taken two hours after. 

If you’re diagnosed with gestational diabetes after having these pregnancy blood tests, you may need to more closely monitor your diet and activity, or you may need to take insulin injections to manage it. A small price to pay for that newborn smell, am I right?!

Maternal serum screening test

A maternal serum screening test is only really necessary if you didn’t have combined first trimester screening done. Again, it’s a blood test that can help identify genetic anomalies in your baby.

If you miss out on this one, you haven’t missed out on free fancy face serums. We can confirm this.

Third trimester pregnancy blood tests

A third trimester blood test during pregnancy isn’t always necessary, but your doctor might request a panel if you’re at-risk or unwell. Blood tests in your third trimester might involve:

  • Assessing your iron levels as they decrease during pregnancy. (An important reason to take those prenatal vitamins, mama!)

  • Infectious diseases or STIs.

What to do with abnormal blood test results during pregnancy

First of all, don’t freak out. In Australia, we usually get blood test results shared with us during physician consultations, so they’ll take you through what they’ve found and what you need to do about it.

Get the facts

Depending on what your abnormal blood test results indicate during pregnancy, you might simply need to pop some more vitamins or take medication. In other scenarios, your doctor might suggest extra tests to work out what’s really going on.

Do more investigating

In some cases, your doctor might recommend further testing outside of your routine prenatal screenings and scans. For example, if your nuchal translucency blood test has indicated a chance of your child being affected by a genetic condition, there are diagnostic tests that can get more solid insight into whether they have it or not.

  • Amniocentesis involves your doctor inserting a needle into your uterus to collect a sample of amniotic fluid for testing.

  • CVS (chorionic villus sampling) takes a sample of the placental tissue for examination.

Both of these tests can provide more clarity, but they do come with a small chance of causing a pregnancy loss.

Seek support

Abnormal pregnancy blood test results can cause worry and panic, we get it. In some cases, your doctor might refer you to a genetic counsellor to help you process information about chromosomal conditions. They can also help you access psychological help to deal with prenatal anxiety or just to work through any worries you have. 

Say ‘yes’ to support, mama!

What other tests will you have during pregnancy?

It’s not just your inner elbow that will be poked and prodded during pregnancy. Expect your vagina and belly to get in on the action too. (They don’t wanna be left out.)

Expect a minimum of two or three pregnancy ultrasounds overall, and at least one uncomfortable peep at your vagina around weeks 35–37 to check for Group B Streptococci bacteria. A visit to your local women’s health physio for a thorough pelvic exam can be super helpful, too (but this one’s not necessary). 

We’ve actually created a very useful breakdown of the pregnancy scans and appointments you can expect throughout your pregnancy (you’re welcome).

And so there you go! Your pregnancy blood tests will look a little something like that. Remember, your doctor will provide tailored advice about what tests you should have. And most importantly, don’t watch the needle go in. That’s all we can say.

Read next: Guide to pregnancy checkups, screenings and scans

The Raising Children Network, Testing in pregnancy

Nemours KidsHealth, Prenatal Tests: First Trimester

Sullivan Nicolaides Pathology, Pathology and Pregnancy

Pathology Awareness Australia, Blood Tests During Pregnancy – What To Expect When You’re Expecting

Sydney Ultrasound for Women, Nuchal Translucency

BetterHealth Channel, Pregnancy tests – maternal serum screening

Victorian Clinical Genetics Services, Maternal serum screening

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