Thalassaemia screening in Singapore: the blood test, your partner's result and your baby

You can get thalassaemia screening in Singapore with one simple blood test at any polyclinic, KKH says. If you carry the trait, your partner gets tested next, because KKH says a child with thalassaemia major inherited a gene from each parent. Test before marriage or pregnancy if you can, or at your first pregnancy visit.

How to get screened for thalassaemia, step by step

1. Ask for a full blood count. KKH says thalassaemia screening is a simple blood test at any polyclinic, and in pregnancy KKH does the count at 10 to 12 weeks.
2. Check your MCV, the average size of your red cells. SingHealth calls an MCV under 80 fL small; iron deficiency is the usual cause, but thalassaemia has to be ruled out.
3. Hold off on iron tablets until your doctor knows why your cells are small. HealthHub asks you to tell your healthcare professional you have thalassaemia before you start iron.
4. Do the follow-up tests your doctor orders. SGH lists haemoglobin electrophoresis or HPLC, plus a DNA test, used especially to confirm alpha trait. KKH's lab lists 2 weeks for its DNA screen.
5. Get your partner tested as soon as you know you're a carrier, because SGH says a baby is at risk only when you both carry the same type (both alpha or both beta).
6. See a doctor together for genetic counselling if you both carry it. KKH advises this before you marry or have a child, and your doctor may refer you to the National Thalassaemia Registry.
7. Ask about a prenatal diagnostic test if you're already pregnant and you both carry it. KKH says chorionic villus sampling is done in weeks 10 to 12, and fetal blood sampling at about 12 to 19 weeks.
8. Tell your parents and siblings your result. KKH says the Registry screens the families of people with thalassaemia, and HealthXchange advises screening for anyone with a family history who plans to have children.

What thalassaemia trait (minor) means

Thalassaemia trait, also called thalassaemia minor, means you carry one thalassaemia gene. KKH says carriers are healthy and lead a normal life, and most don't know they have it. SGH adds that you could have mild anaemia but usually no symptoms or complications. HealthXchange says carriers need no treatment.

It's common here. KKH says about 4.5% of people in Singapore carry a thalassaemia gene, and HealthXchange puts it at 1 in 20. SGH names thalassaemia as the most common inherited haemoglobin condition in Singapore and Southeast Asia.

There are two main types. SGH explains that you have four alpha genes and two beta genes. Beta trait means one beta gene is affected. Alpha trait means one or two of the four alpha genes are affected, and HealthXchange says silent alpha carriers usually show no signs at all. Your type matters once your partner's result comes back.

What the results mean for your baby

These are KKH's chances for each pregnancy. SGH adds that the risk to a baby applies when both parents carry the same type.

KKH says the chances are the same with each pregnancy, however many children you have.

If you both carry alpha trait, SGH says a baby who inherits four affected alpha genes has the most severe form, called Bart's hydrops fetalis, and the mother can have serious complications too. SGH recommends screening for couples planning a baby or already expecting one, and fetal-maternal specialists can test the baby during pregnancy.

Low MCV and iron: check the cause first

A low MCV on your blood count has two common causes. SingHealth says iron deficiency is the most common cause of small red cells, but alpha or beta thalassaemia needs to be ruled out. KKH says the same about pregnancy: iron deficiency is the top cause of anaemia, and thalassaemia can cause it too.

Iron deficiency and thalassaemia trait can both make red cells small, but only one of them is treated with iron. The NHS says a carrier's mild anaemia needs no treatment, and it tells carriers to skip iron supplements unless a test shows iron deficiency anaemia, since iron you don't need could harm you. So when your MCV comes back low, wait for your doctor's call on iron. Our guide to iron in pregnancy covers iron-rich food and the pregnancy blood counts.

Testing before marriage or pregnancy

KKH says you and your partner should be screened if you're planning to get married or starting a family. Testing first means your results and any counselling come before a pregnancy, with no weeks to count. Add it to your preconception check; our trying to conceive guide lists the rest.

Already pregnant? KKH does the full blood count early, at 10 to 12 weeks. Our 8 weeks pregnant guide covers that visit, and prenatal checkups and scans has the full schedule. If you're a carrier, get your partner tested the same week: KKH's window for chorionic villus sampling is weeks 10 to 12. The due date calculator tells you which week you're in.

Who does what in Singapore

If your baby has thalassaemia major

KKH says a baby with thalassaemia major may look normal at birth, then develop severe anaemia within the first one to two years, which affects growth and development. From then on, KKH says, the child needs a blood transfusion every month, while SGH gives every 3 to 5 weeks for people who depend on transfusions. Those transfusions build up iron in the body, so SGH says iron chelation medicine is needed to protect the heart, liver and hormone glands.

KKH names a bone marrow transplant as the only possible cure at present. SGH says a stem cell transplant needs a matched donor, usually a brother or sister, and is usually done in childhood, when results may be better.

Children are cared for at KKH's Children's Blood and Cancer Centre and at NUH, whose paediatric haematology team lists thalassaemia among the conditions it treats. SGH runs a specialist Thalassemia Clinic with doctors, nurses and social workers. For your child's routine checks, see our child health screening guide.

When to see a doctor

Mayo Clinic advises a checkup if your child shows any signs of thalassaemia. It says some babies show signs at birth and others during the first two years. Book a GP or polyclinic visit if your baby:

• Looks pale and listless (HealthXchange)
• Feeds poorly or has a poor appetite (HealthXchange, Mayo Clinic)
• Grows slowly (HealthXchange, Mayo Clinic)
• Has yellow skin or eyes (HealthXchange, Mayo Clinic)
• Seems tired, weak or short of breath (HealthXchange)
• Has a swollen tummy or dark urine (Mayo Clinic)

Tell the doctor if either parent carries thalassaemia trait. For urgent care, KKH says take your child straight to the nearest children's emergency department. KKH and NUH both have one, and NUH's runs round the clock. In an emergency, call 995.

Frequently asked questions

What is thalassaemia trait?

Thalassaemia trait means you carry one thalassaemia gene. KKH says carriers are healthy and most don't know they have it. It matters when you plan a family, because KKH says you can pass the gene on to your children.

Is thalassaemia minor a problem in pregnancy?

Usually not for you. SGH says people with trait could have mild anaemia but usually have no symptoms or complications. KKH checks your blood count early in pregnancy and again at 24 to 28 weeks. If your count is low, your doctor works out whether you need iron.

When is the thalassaemia carrier test done in pregnancy?

KKH does the full blood count at 10 to 12 weeks and offers thalassaemia testing to some women when it's indicated. Ask for it at your first visit. Earlier helps, because KKH does chorionic villus sampling in weeks 10 to 12.

Can two thalassaemia carriers have a healthy baby?

Yes. KKH says when both parents have trait, each pregnancy has a 25% chance of thalassaemia major, a 50% chance of trait and a 25% chance of neither. Genetic counselling and a prenatal test tell you where your pregnancy stands.

How do I know if my baby has thalassaemia in Singapore?

If you both carry the trait, KKH says a prenatal diagnostic test can check the baby during pregnancy. After birth, Mayo Clinic says signs can appear at birth or within the first two years. If your baby looks pale, feeds poorly or grows slowly, see your GP or polyclinic and mention both parents' results.