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Pregnancy blood tests
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Pregnancy blood tests

During pregnancy, you will undergo several blood tests to help protect your health and your baby’s health. Blood tests are an essential aspect of care during pregnancy,

What is a pregnancy blood test?

A pregnancy blood test checks for pregnancy by measuring the human chorionic gonadotropin (hCG) in the blood. Hormone levels increase rapidly in the initial days of pregnancy, usually doubling every 2 – 3 days and peak by week 11. Our test can detect traces of hCG, allowing confirmation of pregnancy as early as possible, even before you miss your period.

Why do I need a pregnancy blood test?

You will need a pregnancy blood test if:

  • You have tested positive on a urine pregnancy kit
  • You think you are pregnant
  • You are pregnant and monitoring hCG levels
  • You are undergoing IVF, and your consultant recommends hCG testing

What blood tests do I need during pregnancy?

When you visit the clinic for a pregnancy test, your doctor will offer the following tests.

  • Blood group

    Knowing your blood group during pregnancy is important in case you need a transfusion during birth or pregnancy. The most common blood group is O. Others include A, B, and AB.

  • Rhesus (Rh) factor

    Your doctor will need to check your rhesus factor. If you are rhesus positive (RhD positive), there is a particular protein on your red blood cells’ surface, but you do not have this protein if you are rhesus negative (RhD).

    If you are RhD negative and your child’s father is RhD positive, your child will likely be RhD positive. In this case, you will react if your blood mixes with the baby’s blood in your womb, producing antibodies that attack the baby’s red blood cells since they differ from yours.

    The antibodies remain in your body forever but won’t be strong enough to affect the current pregnancy. Your antibodies will be primed to attack red blood cells of future pregnancy with RhD-positive pregnancy.

    You can have immunoglobulin injections at week 28 and 3 to prevent your body from making antibodies.

    If you have anaemia resulting from iron deficiency, your GP will likely prescribe iron tablets to ensure your iron levels remain high enough during pregnancy. You will have a haemoglobin level check at week 28. If you are pregnant with twins or more, your GP will arrange extra blood testing at weeks 20 and 24, including the standard week 28 check.

    A blood test known as non-invasive prenatal testing (NIPT) to identify if you and your baby’s rhesus statuses are incompatible. You will only have the immunoglobulin injections if there is a rhesus mismatch.

  • Haemoglobin levels

    You will undergo blood testing to check if your haemoglobin levels are low, indicating iron-deficiency anaemia. Your body requires iron to produce haemoglobin for your red blood cells to transport oxygen.

  • Hepatitis B virus

    Your GP will offer blood tests to check for hepatitis B infection. You can transmit this disease to your baby before or after birth, so the baby needs protection with a series of vaccines and antibodies immediately after birth.

  • Syphilis

    This sexually transmitted disease is now rare. However, if you have syphilis and do not treat it during pregnancy, your baby could develop abnormalities. Syphilis can also cause miscarriage or result in a stillborn.

    An urgent referral to a specialist team is necessary if you have syphilis. Treatment usually involves a course of antibiotics that are safe for the baby. However, your baby will need blood tests and examinations after birth and antibiotics.


    All pregnant women get blood tests for HIV and AIDS. While you may feel uncomfortable having this test, knowing you have the infection helps you take steps to reduce the chances of transmitting the virus to your baby.

Do I need all these blood tests during pregnancy?

These blood tests are optional, but your midwife or doctor will explain the importance of each to help you decide if you want to have them. You may likely feel worried about having these blood tests, especially if you have a phobia for needs or are scared of what the tests may find. However, these blood tests give you and your healthcare provider important information about your pregnancy and your baby’s well-being.

Blood tests during pregnancy are important because they highlight any problems at the early stages so you and your baby can get the right treatment.

Can I request an extra blood test when I am pregnant?

Blood tests for the following are routine, but you can ask your doctor for any test if you think you are at risk of certain conditions.

Toxoplasmosis is an infection gotten from cat poo, undercooked meat, and soil. If you get toxoplasmosis infection for the first time while pregnant, birth defects, miscarriage, or stillbirth may occur.

However, it is rare for unborn babies to get affected by toxoplasmosis. More people in the UK are infected with toxoplasmosis, so you may likely be immune to it before getting pregnant. In the unlikely event you have a toxoplasmosis infection for the first time during pregnancy, you may not pass it to your baby.

If you think you have contracted hepatitis C, you can ask your doctor for a hepatitis C blood test. You may be at risk if you:

  • Are a health worker and had an accidental exposure to hepatitis C
  • Have a history of injecting drugs
  • Had blood transfused or transplant before the introduction of blood screening in 1992
  • Have lived in or received medical treatment in an area with high hepatitis C prevalence, including central and east Asia, the Middle East, and North Africa
  • Have a sexual partner with someone infected with hepatitis C
  • Had body piercings or tattoos in a place where instruments are not sterilised properly

If you have hepatitis C, you will get a referral for treatment and counselling with a specialist.

When will I have blood tests?

Most blood tests are done at once, and your healthcare provider will likely take blood from you during one of your first visits. You may have some blood tests repeated later in pregnancy. Your doctor will discuss this with you.


  • Preparing for test

    Most pregnancy tests are done from the first day you missed your period. If you are not sure where you are in your menstrual cycle or when your period is due, you can have the test at least 21 days after your last unprotected sex.

  • During the test

    A pregnancy test requires a blood sample, which your healthcare professional will take at the clinic.

Pregnancy test results

You should get your blood test results at your next clinic visit. All results are confidential, and you will routinely repeat some tests later in your pregnancy. Your doctor will contact you for advice and case if further investigations are necessary.

Our pregnancy blood test is easy to use, fast, and efficient, with a fast turnaround time. Contact Medical Express Clinic on 0207 499 1991 today to book your pregnancy blood test appointment. Same-day appointments are also available.