Blood tests in pregnancy

We recommend you have these early pregnancy tests as soon as possible after you know you are pregnant. Knowing whether you have these conditions can help keep you and your pēpi well.

When you see your midwife or doctor for the first time about your pregnancy, they will offer you these 7 tests. The tests are free and are taken from 1 blood sample.

Full blood count

This blood test checks your red blood cells. If this is low, this is known as anaemia.

The most common cause of anaemia in pregnancy is low iron.

There is advice on getting iron in pregnancy on our Nutrients and Supplements page.

Nutrients and supplements (internal link)

If you have low iron, your midwife or LMC may advise you to take iron tablets.

The test also checks your platelet levels and white cells. Platelets help your blood to clot, while white cells are part of your immune system to fight infection.

Blood group and antibodies

This test checks your blood group and for the presence of antibodies (part of your immune system). Your blood group can be A, B, O or AB.

Some antibodies can be harmful for your baby during pregnancy. Monitoring and treatment are recommended if you do have antibodies that could affect your pēpi.

Rhesus factor

One of the antibodies that will be checked is your rhesus factor (Rh D). You are either Rh positive or Rh negative.

If you are Rh negative and your blood mixes with your baby’s blood you can make antibodies which can cause severe anaemia and jaundice (yellowing of the skin and eyes) in this or your next baby.

Your blood can only mix with the baby’s if you bleed during:

• pregnancy
• a miscarriage
• an abortion
• during the birth.

An injection of anti-D after any of these can prevent your body from making these harmful antibodies.

Rhesus negative blood group — anti-D injection (internal link)

Rubella (German measles)

This test checks whether you are protected (immune) against rubella. If you catch the rubella virus in pregnancy it can lead to severe problems for your pēpi, for example:

• deafness
• brain injury
• miscarriage.

If you are not immune you can have a vaccine called MMR to prevent problems in future pregnancies.

This vaccine can only be given when you are not pregnant.

Measles, mumps and rubella (MMR) vaccine (internal link)

Hepatitis B

Hepatitis B is a virus that can be passed to your pēpi during birth. You may have this disease but not know because there are often no symptoms. Hepatitis B can cause significant health problems, including liver damage.

About 20% of babies exposed to hepatitis B during birth and left untreated, become infected. Over 90% of untreated babies become carriers of the virus.

If have hepatitis B you will be offered immunoglobulin and immunisation at birth. This will help prevent your pēpi becoming infected.

• Hepatitis B (external link)
• Hepatitis B vaccines (external link)

HIV

Human immunodeficiency virus (HIV) affects your body’s ability to fight infection. It can cause AIDS. HIV is passed on to others by contact with blood or body fluids.

If you have HIV, it can be passed on to your pēpi during pregnancy, birth or breastfeeding. New medicines can protect your baby and help you to stay well.

HIV testing in pregnancy (internal link)

Syphilis

Syphilis is a rare infection in Aotearoa New Zealand, but it is becoming more common. Most people with syphilis do not know they have the disease because they feel well and have no symptoms.

Syphilis can cause serious health problems for you and your unborn pēpi if it is not treated. It can be passed on to your pēpi during pregnancy. A blood test in early pregnancy, and treatment if needed, can help to avoid these problems.

Diabetes

Diabetes is when you have too much sugar in your blood. Many people do not know they have diabetes and have no symptoms. During pregnancy it can make you sick and affect your baby’s growth. If you already have diabetes, or you develop diabetes in pregnancy, you will be offered information, treatment and support.

Diabetes testing is offered twice in pregnancy. The first test checks if you have diabetes or are prone to developing diabetes. The later test tells you whether you are developing diabetes while you are pregnant.

Testing for diabetes in pregnancy (internal link)