Thalassaemia and SMA Carrier Screening Before Pregnancy: What Every Indian Couple Should Know

There is a conversation I have with couples in my clinic that never gets easier. Not because the medicine is complicated. But because it comes too late.

A couple has been trying to conceive. They come in after months of disappointment, or after a pregnancy that ended badly, or sometimes after the birth of a child with a condition that was entirely preventable. And somewhere in that conversation, it becomes clear that a simple blood test done before any of this began would have changed everything.

Thalassaemia carrier screening. SMA carrier screening. Two tests. One blood draw each. Done before you start trying. This is why thalassaemia carrier screening before pregnancy India is becoming an essential part of preconception planning for couples who want to reduce the risk of passing on inherited blood disorders. 

That is what this blog is about.

What Is Carrier Screening and Why Being a Carrier Is Not the Same as Being Affected

Before I explain what we are testing for, let me explain what a carrier is because this is the piece that most people misunderstand when they first hear the term.

Thalassaemia and SMA are both recessive genetic conditions. This means a single copy of the abnormal gene, which is what a carrier has, causes no disease at all. Carriers are completely healthy. They have no symptoms. They live full, normal lives. Most of them have no idea they carry anything.

The problem arises when two carriers have a child together.

When both parents carry a single abnormal copy of the same gene, each pregnancy carries a one in four chance, 25 per cent, of the child inheriting both abnormal copies and being born with the full disease. Not a small risk. Not a rare possibility. One in four. Every single pregnancy.

Being a carrier is not a problem. Being a couple where both partners are carriers and not knowing it is a problem that is entirely preventable.

This is why carrier screening belongs in preconception planning, not in antenatal care. Carrier screening preconception gives couples more reproductive options and greater peace of mind before pregnancy. When you find out during pregnancy that both of you are carriers, your options narrow sharply and your decisions become far more painful. When you find out before conception, before any embryo exists, your options are wide open.

This is one of the reasons why preconceptional counselling in Kolkata is recommended for couples planning a pregnancy, as it helps identify genetic risks and discuss appropriate carrier screening before conception. 

Thalassaemia – The Numbers Every Couple in India Needs to Know

India carries the largest burden of thalassaemia in the world. Approximately 3 to 4 per cent of the general Indian population are thalassaemia carriers, meaning roughly one in every 25 to 30 people you meet on the street carries this gene. Around 10,000 to 12,000 children with thalassaemia major are born in India every year. Every single one of those births was, in principle, preventable.

But the number that matters most if you are reading this in West Bengal or anywhere in eastern India is this: the carrier rate in Bengal is significantly higher than the national average. The high prevalence of thalassaemia Bengal highlights the importance of carrier screening for couples from this region. Studies have documented thalassaemia carrier frequencies of 10 per cent or more in certain Bengali communities, meaning in some populations, one in ten people is a carrier. When both partners come from the same community, the probability of both being carriers rises considerably above what national statistics suggest.

This is not a reason for panic. It is a reason for testing. Considering the high carrier rates across the country, thalassaemia carrier screening before pregnancy India gives couples the opportunity to understand their genetic risk before conception. A carrier who knows they are a carrier can plan. A carrier who does not know cannot.

How We Test – HPLC

The test I use for thalassaemia carrier screening is HPLC High Performance Liquid Chromatography. It is a blood test that analyses haemoglobin fractions and identifies abnormal haemoglobin variants with a high degree of accuracy. An HPLC tests before pregnancy helps identify thalassaemia carriers early, allowing couples to make informed reproductive decisions. 

HPLC is more sensitive than older haemoglobin electrophoresis methods and can detect a wider range of thalassaemia variants and haemoglobin disorders. If you have had a haemoglobin electrophoresis done previously and it was reported as normal, it is worth confirming with HPLC, particularly if you are from a high-prevalence community or have any family history of anaemia or thalassaemia.

If your HPLC result identifies you as a carrier, the next step is immediate and non-negotiable: your partner must be tested too. The result that matters is not one partner’s result in isolation. It is what both results together mean for your pregnancies.

Spinal Muscular Atrophy – The Condition Most Couples Have Never Heard Of

If thalassaemia is the condition most Indian couples have heard of but underestimate, SMA is the condition most have never heard of at all until it is too late. SMA carrier screening India is equally important because many healthy individuals are unaware that they carry the SMN1 gene mutation. 

Spinal Muscular Atrophy is a severe genetic condition affecting the motor nerves. Children born with the most serious form of SMA, type 1, typically cannot breathe, swallow, or move without support. It is one of the leading genetic causes of infant death in the world. In India, the carrier frequency is estimated at approximately one in 40 to one in 50, far higher than most couples realise.

Like thalassaemia, SMA follows the same inheritance pattern. Both parents must be carriers for the child to be affected. Both carriers are entirely healthy. And the risk per pregnancy, when both parents carry the SMN1 gene mutation, is one in four.

The difference between thalassaemia and SMA is this: thalassaemia major, while devastating, is manageable with lifelong blood transfusions. SMA Type 1 is not manageable in the same way. New gene therapies exist, are expensive, are extraordinary, and are not universally accessible. The far better outcome is prevention.

How We Test – MLPA

SMA carrier screening is done using MLPA (Multiplex Ligation-dependent Probe Amplification). It is a specialised blood test that detects deletions in the SMN1 gene, which is the most common cause of SMA. MLPA genetic screening is the preferred method for detecting SMN1 gene deletions responsible for most cases of spinal muscular atrophy. 

MLPA is not a test available in every laboratory. It needs to be specifically requested. Many couples go through their entire antenatal care without anyone mentioning it. This is one of the reasons I include it as a standard part of my preconception screening panel not because every couple will be carriers, but because the couples who are deserve to know before pregnancy, not during it.

What Happens When Both Partners Are Carriers

This is the conversation I prepare for carefully every time. Because it is not a conversation anyone expects to be having when they walk into a preconception clinic feeling completely healthy.

Both of you are carriers. That sentence lands differently for different couples. Some are frightened. Some are relieved to know. All of them want to understand what it means for them now.

Here is what I tell them.

Why I Always Recommend IVF with PGT-M and Not Prenatal Diagnosis

There are two paths available to couples where both partners are carriers of a recessive condition like thalassaemia or SMA.

The first is prenatal diagnosis: conceiving naturally and then testing the pregnancy through CVS (chorionic villus sampling) or amniocentesis in the first or second trimester to find out whether the baby has been affected. If the result comes back showing the baby has thalassaemia major or SMA Type 1, the couple faces a decision about whether to continue the pregnancy.

The second is IVF with PGT-M (Preimplantation Genetic Testing for Monogenic disorders). Eggs are retrieved, fertilised in the laboratory, and the resulting embryos are tested before any transfer takes place. Only embryos confirmed to be unaffected are transferred. The pregnancy that results is a pregnancy where you already know the baby does not have the condition. This approach is an important part of monogenic disorder screening India, helping couples prevent the transmission of single-gene disorders to future generations. 

I always recommend IVF with PGT-M. Without hesitation. And I want to tell you exactly why not in clinical language, but in the same words I use with every couple who sits in front of me.

PGT-M thalassaemia India offers carrier couples an opportunity to reduce the risk of passing thalassaemia to their children by selecting unaffected embryos before transfer. 

Yes, you could do a prenatal diagnosis. But think about what that means. You conceive. You wait. You do the test at 11 or 16 weeks. And then you wait again for results that could tell you the pregnancy you have fallen in love with needs to be terminated. That is emotional heartbreak layered on physical trauma. And for what? When prevention was already available to you.

There is no cure for thalassaemia major. There is no cure for SMA Type 1. These are not conditions we treat and move on from. They are conditions that a child lives with, or dies from, and that families carry for the rest of their lives.

PGT-M prevents that from happening. It allows you to transfer only an embryo that is unaffected. You still go through IVF; that is not a small thing, and I do not minimise it. But you go through it once, with a plan, before anything has gone wrong. The alternative is conceiving naturally, falling pregnant, and then going through the agony of a result that requires you to end a pregnancy you already wanted.

In my clinical opinion, and in my experience of walking with couples through both paths, there is no comparison. Prevention is always better than cure. And when there is no cure, when the only options are lifelong suffering or termination, prevention is not just better. It is the only answer that makes sense.

I always offer prenatal diagnosis as an option. Couples have the right to know every path available to them. But I am honest about what each path involves. And I have never had a couple, once they truly understood both options, choose prenatal diagnosis if PGT-M were available to them.

When Should You Do Carrier Screening and Who Should

The answer to who is simple: every couple planning a pregnancy. Not just couples with a family history. Not just couples from high-risk communities. Every couple.

Carriers have no symptoms. Family history is an unreliable guide because previous generations may not have been tested or because affected children may not have survived to be remembered. The only way to know your carrier status is to test.

The answer to when is equally simple: before you start trying. Not at your first antenatal appointment. Not after a positive pregnancy test. Before.

For every couple planning a family, thalassaemia carrier screening before pregnancy India should be considered an important part of preconception care alongside other recommended genetic screening tests. 

If you find out you are both carriers after you are already pregnant, your options are limited and your decisions are painful. If you find out before, you have time. You have choices. You have the ability to plan a pregnancy that begins with certainty rather than anxiety.

Carrier screening is the closest thing I know to flying first class before your child is even conceived. It is the most proactive thing you can do. And in a country where the carrier rates for both thalassaemia and SMA are as high as they are in India, it is not a test for the cautious few. It is a test for every couple who wants to give their child the best possible beginning.

Related Blog: Expanded Carrier Screening

Frequently Asked Questions

If I have a family history of thalassaemia, does that mean I am definitely a carrier?

Not necessarily, but it significantly increases the probability and makes testing even more urgent. A family history tells me there is a known carrier in your family tree. Whether you inherited that gene depends on who was affected and what your relationship to them is. The only definitive answer is a blood test. Do not assume either way.

My last blood test said my haemoglobin was normal. Does that mean I am not a thalassaemia carrier?

No. A normal haemoglobin level does not rule out thalassaemia carrier status. Many carriers have a slightly low MCV (mean corpuscular volume) on a blood count, but some have completely normal routine blood tests. HPLC is a specific test for haemoglobin variants; it is not the same as a routine haemoglobin measurement. You need HPLC specifically.

Is IVF with PGT-M covered by insurance in India?

Coverage varies widely by insurer and plan. Many standard health insurance policies in India do not cover IVF or PGT-M. Newer, more comprehensive policies sometimes include fertility treatments. It is worth checking with your insurer specifically. What I would say is this: the cost of PGT-M, relative to the lifelong financial, physical, and emotional cost of managing thalassaemia major or SMA in a child, is not a comparison that favours waiting.

We are already pregnant. Is it too late for carrier screening?

It is not too late for carrier screening itself, both of you can still be tested during the pregnancy. If one or both of you come back positive, we can then discuss prenatal diagnostic options, including CVS or amniocentesis, to test the pregnancy directly. The conversation changes once you are already pregnant, but it does not end. Come in and we will work through the options together.

If only one of us is a carrier, does our child have any risk?

If only one partner is a thalassaemia or SMA carrier, your children cannot be born with the full condition. They may be carriers themselves inheriting the single gene copy from the carrier parent, but they will be healthy, just as you are. The clinical risk arises only when both partners carry the same recessive gene. This is why both partners must be tested, not just one.

Know before you begin.

Carrier screening is one of the most important things you can do before you start trying to conceive — and one of the simplest. A blood test each. Done once. Before any of this becomes harder than it needs to be. Book your preconception consultation at Renew Healthcare and we will guide you through every step.

WhatsApp / Call: +91 62922 69060

Download your free Zero Trimester Guide: drrajeevagarwal.co.in/preconception/

— Dr. Rajeev Agarwal | Fertility Specialist & Gynaecologist, Renew Healthcare, Kolkata

Don’t just conceive, preconceive. — Dr. Rajeev Agarwal

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