Understanding your pregnancy – Blood and urine tests

Read our midwife’s guide to blood and urine tests…


In your diary at… 10 weeks

These tests should be done as early as possible. Your midwife may discuss them at your first appointment and, depending how many weeks pregnant you are, get you back a couple of weeks later to take a blood sample and urine test to check for the various conditions. That way, you’ll have had time to think about whether or not you’re happy to have them all done.


Urine infections:

Your midwife will test your urine at each appointment for protein, which can be a sign of a condition called pre-eclampsia. But she’ll probably also advise that a sample of urine is tested before 12 weeks of pregnancy to check for any infection.


A very common sexually-transmitted infection that often has no symptoms, but if untreated can spread and cause miscarriage, premature birth, or eye and lung infections in the baby. If a urine test detects this in pregnancy, it can be treated with a course of antibiotics.


A sexually-transmitted infection that, if not treated, could result in miscarriage or stillbirth. You’ll be offered a blood test to check for it, and, if caught early, it can be treated with antibiotics.


You’ll be advised to have a blood test to check for anaemia at the start of your pregnancy and again at around 2834 weeks. Severe anaemia can affect your baby’s growth, while mild anaemia can leave you feeling tired and run down.

Blood group and Rhesus factor:

It’s important to know what your blood group is in pregnancy, in case you need a blood transfusion. If your blood is Rhesus negative you’ll be advised to have an injection of a substance called Anti-D while pregnant, to stop you producing antibodies that may harm your baby.


Women with this virus, which causes AIDS, can pass the infection on during pregnancy, birth or breastfeeding. But treatment can significantly reduce the risk of your baby becoming infected, which is why this blood test is advised.

Hepatitis B:

If this virus is passed onto your baby it could cause serious problems including liver disease, but if your blood tests positive for hepatitis B, your baby can be immunised to help prevent infection.


This blood test checks if you’re immune to rubella (German measles). Rubella harms 90 per cent of babies if the mum-to-be catches it in the first trimester.


If your midwife decides you’re at risk of developing diabetes while pregnant (gestational diabetes), she’ll recommend you have a glucose tolerance test between 24 and 28 weeks of pregnancy. This involves blood tests taken after you’ve been given a very sweet drink.

Sickle cell and thalassaemia:

These are serious inherited blood conditions that need specialist care throughout the patient’s life. The blood test for thalassaemia is offered in early pregnancy, where you’ll be asked questions about your origin and that of your baby’s father to decide if a further test for sickle cell is needed. Couples with an ancestor from outside northern Europe are more likely to be carriers of these conditions. Carriers can’t develop the disorder but if both parents are carriers, their child could inherit the condition.


And then…

Between 10 and 18 weeks of pregnancy, you’ll be offered a screening test that measures various substances in your blood that can indicate an increased risk of having a baby with Downs Syndrome. This can be offered alongside the nuchal scan, or by itself if the nuchal scan is not available in your area. This might be taken by your midwife, healthcare assistant or phlebotomist (person who specialises in taking blood).

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