Antenatal Blood Tests

During the first antenatal visit, the following blood tests are offered to pregnant women:

Blood Grouping

It is important to know the blood group of the pregnant woman in case she needs a blood transfusion. The four main blood groups are O, A, B and AB.

Rhesus (Rh) Factor

Rh factor is an antigen found in red blood cells. Individuals who possess this factor are classified as ‘Rh positive’ and those without it as ‘Rh negative’. When a ‘Rh negative’ mother is carrying a Rh positive foetus, problems can occur in the foetus such as haemolytic anaemia, oedema or even death. Regular blood test will then be needed.

Haemoglobin and Mean Cell Volume

These tests help to find out whether the pregnant mother has anaemia. Mean cell volume (MCV) is a simple and easy test which helps to find out who has a higher chance of carrying the thalassaemia genes or iron deficiency anaemia.

Rubella Antibody

A woman who has received Rubella vaccine or contracted Rubella before conception should have developed immunity, that is, having Rubella antibodies. This can protect her from contracting Rubella during pregnancy. Rubella infection may cause fetal abnormalities. If the woman does not have Rubella antibody, she should receive Rubella vaccine after delivery.

Hepatitis B Antigen

If the blood test is positive for Hepatitis B antigen, then the mother is a carrier. A mother who is a Hepatitis B carrier may transmit the virus to the infant at or around the time of delivery. The newborn should receive Hepatitis B vaccine and Hepatitis B immunoglobulin after birth so as to protect him against Hepatitis B infection.


Untreated syphilis in pregnancy may result in miscarriage or cause fetal congenital defects such as blindness or deafness. Therefore, early detection and treatment are necessary.

Human Immunodeficiency Virus (HIV) Antibody Testing

HIV can cause AIDS (Acquired Immune Deficiency Syndrome). The routes of transmission include sexual intercourse, blood contact or from an infected mother to her baby during pregnancy, delivery or breastfeeding. The transmission rate from an infected mother to her baby is 15%-40%. Early detection and antiviral treatment can reduce the risk of HIV transmission from mother to child by two-thirds.

Other tests

You doctor may also suggest you to have Toxoplasma gondii, Cytomegalovirus, Herpes Simplex virus and Parvovirus B19 tests. If pregnant women were infected from the above virus in the early gestation, the fetus may result in miscarriage or cause fetal congenital defects.