Genetic Testing Before Pregnancy: What Every Couple Should Know

Most people think genetic diseases only affect families with a known history of inherited conditions.

In reality, **millions of healthy people carry genetic variants without ever knowing it.**

This is why more fertility specialists now recommend **genetic carrier screening** before trying to conceive—whether naturally or through IVF.

A simple blood or saliva test can identify whether you and your partner carry the same inherited condition and help you understand your reproductive options before pregnancy begins.

A Quick Genetics Lesson

Every person inherits two copies of most genes:

• One copy from their mother.
• One copy from their father.

Genes contain the instructions that tell our bodies how to grow and function.

Most people carry a few genetic changes (called **variants** or **mutations**) that have no effect on their own health.

These changes are surprisingly common.

Being a **carrier** usually does **not** mean you have a disease.

Most carriers are completely healthy and never know they carry a genetic variant.

What Is Carrier Screening?

Carrier screening is a genetic test that looks for hundreds of inherited diseases before pregnancy.

Both partners are tested.

The goal is simple:

**To find out whether both partners carry a disease-causing variant in the same gene.**

If only one partner is a carrier, there is usually no risk that the child will develop that particular recessive disease.

If both partners carry variants in the same gene, each pregnancy carries a risk that the child could inherit the condition.

How Are Genetic Diseases Inherited?

Many inherited diseases follow an **autosomal recessive** pattern.

This means a child must inherit one altered copy of the gene from **each parent** in order to develop the disease.

If **both parents are carriers**, each pregnancy has:

• **25% chance** of a child affected by the disease.
• **50% chance** of a healthy child who is also a carrier.
• **25% chance** of a child who inherits neither altered gene.

These probabilities are the same for every pregnancy.

Having one healthy child does not change the chances for the next pregnancy.

How Common Is It?

Many people are surprised to learn that **everyone carries several genetic variants**.

Most carriers never develop symptoms because they also have one healthy copy of the gene.

Studies suggest that approximately **1 in 150 to 1 in 200 couples** are carriers of the same recessive condition without knowing it.

Most have no family history of the disease.

Which Diseases Can Be Detected?

Modern expanded carrier screening panels can test for **hundreds of inherited conditions**, including:

• Cystic fibrosis
• Spinal muscular atrophy (SMA)
• Sickle cell disease
• Tay-Sachs disease
• Fragile X syndrome (in selected cases)
• Hundreds of other rare inherited disorders

The exact diseases included depend on the laboratory and the test you choose.

Who Should Consider Carrier Screening?

Many professional societies now support offering carrier screening before pregnancy or early in pregnancy.

It may be particularly valuable if:

• You're planning your first pregnancy.
• You're considering IVF.
• You're planning egg or sperm freezing before future family building.
• You or your partner have a family history of an inherited disease.
• You're using donor eggs or donor sperm.
• You and your partner come from the same ethnic background where certain inherited conditions are more common.

Many couples without any obvious risk factors also choose carrier screening for reassurance.

What Happens If Both Partners Are Carriers?

Finding out that both partners carry the same condition can be frightening—but it also provides valuable information before pregnancy.

Depending on the condition, your options may include:

• Conceiving naturally with prenatal testing during pregnancy.
• IVF with **Preimplantation Genetic Testing for Monogenic Disorders (PGT-M)** to identify embryos that have not inherited the disease.
• Using donor eggs or donor sperm.
• Adoption.
• Choosing to conceive naturally after genetic counselling and understanding the risks.

There is no single "right" decision.

The goal of carrier screening is **to provide information**, allowing couples to make informed choices that align with their values.

Is Carrier Screening the Same as PGT-A?

No.

These tests answer completely different questions.

One test does not replace the other.

Is Carrier Screening Worth It?

For many couples, the answer is yes.

Most people receive reassuring results.

For the small percentage of couples who discover they carry the same inherited condition, the information can significantly influence reproductive planning and may open additional options before pregnancy begins.

Because the test only needs to be performed **once in a lifetime**, many fertility specialists consider it one of the most valuable investigations before trying to conceive.

Bboom Tip

Carrier screening isn't about expecting something to be wrong—it's about reducing uncertainty.

Most couples discover they are **not** carriers of the same condition. For those who are, learning this before pregnancy provides more choices, more time to plan, and the opportunity to discuss options such as IVF with PGT-M or genetic counselling.

Genetic testing cannot eliminate every risk, but it can help you make more informed decisions as you build your family.

**Related reading**

• _IVF Step by Step_
• _Understanding PGT-A and PGT-M_
• _Preparing for IVF: Tests, Supplements & Lifestyle_
• _Questions to Ask Your Fertility Doctor_