Blood tests are a routine part of your antenatal care. While it's natural to feel anxious about them, they give important information about your and your baby's health.

These are the six routine blood tests that every mum-to-be has to undergo around week 7 of pregnancy:

Full blood count

This measures your haemoglobin level to detect anaemia (low levels of red blood cells that carry oxygen in your body). You'll be prescribed iron supplements if you're anaemic. A repeat blood test may be recommended at week 28 to recheck the haemoglobin levels.

It also screens for thalassemia, a common genetic blood disorder in Asia where an abnormal form of haemoglobin is formed. Most carriers don't show any symptoms, and may not even be aware of their carrier status. If both mum and dad-to-be are carriers, the baby may be affected. Further tests will be carried out on you and your partner if either of you tested positive.

Blood typing

Knowing your blood group (A, B, O or AB) and Rhesus (Rh) status is useful in emergency situations like excessive bleeding. If you are Rh negative, injections may be required during your pregnancy to prevent harmful antibodies — that may affect your baby — from being produced.

Hepatitis B screening

If you're a Hepatitis B carrier, a Hepatitis B vaccine and antibodies will be administered to your baby immediately after delivery to minimise the risk of liver problems in later years.

Syphillis screening

While this sexually transmitted disease is rare, screening is routine as infection can be transmitted to your baby through the placenta during pregnancy. If detected in mum-to-be, early treatment with antibiotics may prevent stillbirth and deformities.

HIV screening

Human Immunodeficiency Virus (HIV) causes AIDS (Acquired Immunodeficiency Syndrome), which affects the immune system and may eventually cause death. A pregnant woman who is HIV positive can transmit the virus to her baby during birth and breastfeeding. However, detection via early screening can facilitate proper treatment with medication. A planned Caesarean section may be necessary. Avoiding breastfeeding can reduce the risk of transmission to baby to less than one percent.

Oral Glucose Tolerance Test (OGTT)

This tests for diabetes in pregnancy (gestational diabetes) and will require you to fast overnight beforehand. It's usually done between weeks 24 and 28. After a blood specimen is taken, you will need to drink a glucose solution before your blood glucose levels are measured again at one and two-hour intervals. One in five women tests positive for gestational diabetes. Blood sugar monitoring in pregnancy can optimise outcomes in such cases.


Explore more

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• Screening scans for trimester 2
  
• 3 things third trimester growth scans can tell you
  
• Genetic disorder: is my baby at risk?

Associate Professor Tan Thiam Chye
Visiting Consultant, Department of Obstetrics and Gynaecology, KKH

Dr Tan Shu Qi
Consultant, Department of Obstetrics and Gynaecology, KKH

Sources:
The New Art and Science of Pregnancy and Childbirth 2008, World Scientific
Healthy Start for your Pregnancy 2012, Health Promotion Board Singapore

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