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Thalassaemia: what is the risk for your child?

Your haemoglobin result and the result of the donor or the father decide your child’s chances. Choose both results from your haemoglobin tests, and the calculator shows what can happen in each pregnancy.

Checked October 2026Worked out on your phone, nothing is sent

A guide only, not medical advice. Your answers stay on your phone and are sent nowhere.

What thalassaemia is

Thalassaemia is a group of inherited blood conditions. The body makes too little haemoglobin, the part of red blood cells that carries oxygen. A person who carries one changed gene is a “carrier”, or has the “trait”. A carrier is healthy. The illness comes when a child receives a changed gene from both parents.

How the calculator works

Beta-thalassaemia and HbE are changes in the same gene, the beta-globin gene. Everyone has two copies of it. Each parent gives one copy to the child, by chance. So there are four possibilities, each with the same chance. The chances start again in each pregnancy: one ill child does not protect the next one, and one healthy child does not either.

Example: both parents have beta-thalassaemia trait. In each pregnancy, the child has a 1 in 4 chance of being normal and 2 in 4 of being a carrier. The child also has a 1 in 4 chance (25%) of beta-thalassaemia major, a serious illness. If one parent is normal, no child can have the illness, but half of the children may be carriers.

What each result means

  • Normal: no beta-thalassaemia or HbE gene.
  • HbE trait: a healthy carrier. Blood counts are normal or nearly normal.
  • Beta-thalassaemia trait: a healthy carrier. The red cells are small, and the HbA2 level is raised on the test.
  • HbE disease (two HbE genes): usually mild.
  • HbE/beta-thalassaemia: one HbE gene and one beta-thalassaemia gene. It goes from mild to severe: some people never need a transfusion, others need them regularly. The exact beta gene change and other genes, including alpha-thalassaemia, make the difference.
  • Beta-thalassaemia major: two beta-thalassaemia genes. A serious illness.

How common carriers are in your country

These studies use different groups and methods, so the numbers cannot be compared exactly. They show that carriers are common everywhere in the region, and very common in some areas.

  • India: 2.78% carry beta-thalassaemia trait (study of 56,780 people in six cities, 2013). HbE is common in the north-east: 23.9% in Dibrugarh, Assam, against 3.92% in Kolkata.
  • Malaysia: about 1 in 20 Form 4 students screened from 2016 to 2018 carried a thalassaemia gene.
  • Indonesia: 3 to 10% of people carry thalassaemia, says the Ministry of Health (2023).
  • Thailand: 3 to 9% carry beta-thalassaemia, and 30 to 50% carry HbE, most in the north-east.
  • Vietnam: 13.8% of people carry a thalassaemia gene, from under 1% to 88.6% depending on the ethnic group. The Ministry of Health counts nearly 10 million carriers and about 8,000 affected babies a year, 2,000 of them severe (2024).
  • Cambodia: HbE in 55.9% of people tested in Preah Vihear (2016), fewer in Phnom Penh.
  • Laos: among pregnant women in Vientiane, 30.2% carried HbE and 3.6% beta-thalassaemia.
  • Myanmar: only small regional studies, no national survey. In Shan State, 17.6% carried HbE.

Alpha-thalassaemia: a different gene, not in this calculator

Alpha-thalassaemia is on another gene, the alpha-globin gene. Each person has four copies. It is very common in Thailand and Laos: among pregnant women in Vientiane, 12.7% carried the most serious form, with two copies missing on the same side.

This matters most when both parents carry it. The common form here is called “--SEA” (Southeast Asian deletion). If both parents carry --SEA, each pregnancy has a 1 in 4 (25%) chance of Hb Bart’s hydrops fetalis. In that condition the baby has no working alpha genes. Most of these babies are stillborn or die soon after birth. The mother also risks pre-eclampsia (high blood pressure in pregnancy), an early delivery and heavy bleeding. If three copies are missing, the child has HbH disease: a mild to moderate anaemia, and usually a normal life into adulthood.

The usual haemoglobin test cannot confirm alpha-thalassaemia trait. If your red cells are small (low MCV or MCH) but your HbA2 is normal, ask for a DNA test for alpha-thalassaemia, at least for --SEA. Lack of iron also makes red cells small, so a low MCV alone is not a diagnosis.

How to get tested

Ask for a full blood count with haemoglobin electrophoresis or HPLC (a machine test that measures each type of haemoglobin). In Thailand, screening also uses a quick HbE test called DCIP. Both of you should be tested, ideally before a pregnancy.

  • India: the Ministry of Health and Family Welfare has national guidelines on haemoglobin disorders (2016). Indian expert guidance advises HPLC before pregnancy or at the first antenatal visit, and testing the partner at once if the woman is a carrier. It is not yet part of standard antenatal care everywhere, and programmes vary by state.
  • Malaysia: Form 4 students have been offered screening since 2016. In 2025, the Ministry of Health published a plan to 2030 to widen screening before marriage and in pregnancy.
  • Indonesia: the Ministry of Health recommends screening before marriage, for teenagers and for families of patients. We found no binding national programme.
  • Thailand: antenatal care screens the pregnant woman, then her partner if she is a carrier, and offers prenatal diagnosis to couples at risk.
  • Vietnam: a national programme approved in 2021 began in five provinces. Testing before marriage is advised, not compulsory.
  • Cambodia, Laos and Myanmar: we found no national screening programme. Ask a hospital laboratory for the tests.

If you both carry a gene

Ask for genetic counselling: a doctor explains your results and your chances. Prenatal diagnosis tests the baby during the pregnancy, so you know early. This is how the Thai antenatal programme works for couples at risk. For couples who both carry --SEA, medical guidance advises prenatal testing, or testing embryos before transfer during IVF (preimplantation testing). A doctor will explain the choices that exist in your country.

What the calculator does not cover

It covers beta-thalassaemia and HbE only. It does not cover alpha-thalassaemia, sickle cell, or rare haemoglobin changes. If someone in the family is ill and the results do not explain it, talk to a doctor.

Sources

  • GeneReviews, beta-thalassaemia (PubMed 20301599) and alpha-thalassaemia (PubMed 20301608); MedlinePlus Genetics, alpha-thalassaemia; review of HbE/beta-thalassaemia, PMC3237252.
  • Indonesia, Ministry of Health (Kemenkes), thalassaemia prevention, 8 May 2023.
  • Mohanty et al., six Indian cities, Journal of Community Genetics, 2013; MoHFW and NHM, Prevention and Control of Hemoglobinopathies in India, 2016; SGPGIMS screening guidelines; FOGSI good clinical practice recommendation, 2025.
  • Malay Mail, Form 4 screening results, 27 January 2021 and 1 November 2025; The Vibes, Ministry of Health thalassaemia plan, June 2025.
  • Mediterranean Journal of Hematology and Infectious Diseases, 2018 (Thailand); Khon Kaen couple screening, Southeast Asian Journal of Tropical Medicine and Public Health, 2016.
  • Bach et al., Hemoglobin, 2022 (Vietnam); Viet Nam News, Ministry of Health figures, 2024; NGO Centre Vietnam, national programme, 2021.
  • Mahidol University study in Cambodia, 2016; Savongsy et al., Vientiane (Laos); Kawasaki Medical School study in Shan State (Myanmar).
  • Lampang study on alpha-thalassaemia testing, Journal of Health Science and Medical Research; American Society for Reproductive Medicine (ASRM), gamete donation guidance, 2024.

Before you choose a donor or a co-parent, ask for his haemoglobin test result. See tests to ask a donor for. His dated results are on his health and fertility.