Can genetic testing help explain why I'm having recurrent miscarriages?

Losing a pregnancy is deeply distressing. When it happens repeatedly - usually defined as three or more losses in a row - it’s called recurrent miscarriage. Around 1 in 100 couples experience this. Many feel desperate for answers: why is this happening, and could it happen again?

Genetic factors are one important piece of the puzzle. They don’t explain every case, but testing can sometimes provide clarity and help you and your healthcare team plan ahead.

Why genetic problems cause miscarriage

Most miscarriages happen because the embryo has a chromosomal abnormality - it has too many or too few chromosomes, or a piece of a chromosome is missing or rearranged. These changes usually happen by chance when the egg or sperm forms, or very early after fertilisation. They often prevent the embryo from developing normally.

As people age - particularly women over 35 - the chance of chromosomal problems in eggs increases. This is why miscarriage becomes more common with age. But chromosomal problems can happen at any age, and they’re the most frequent genetic cause of early pregnancy loss.

In a smaller number of cases, one or both parents carries a chromosomal rearrangement in their own cells. They’re usually healthy themselves, but the rearrangement can make it harder to produce chromosomally normal eggs or sperm. This increases the chance of miscarriage or, less commonly, of having a baby with a genetic condition.

What genetic testing can find

Genetic testing for recurrent miscarriage usually focuses on two main areas:

Testing the pregnancy tissue (products of conception)

If you have another miscarriage, your doctor may suggest testing the pregnancy tissue itself. A laboratory technique called chromosomal microarray analysis can look at all 24 types of chromosome and detect extra or missing copies, as well as some smaller changes.

Research involving over 65,000 miscarriages found that chromosomal abnormalities in the pregnancy tissue explain more than half of losses. In one study of 378 couples with recurrent miscarriage who had this testing, aneuploidy (an abnormal number of chromosomes) was found in the pregnancy tissue in 57.7% of cases. This information can be reassuring: it suggests the loss was due to a random chromosomal event, not an ongoing problem in either parent.

Testing the parents (karyotype analysis)

A karyotype test examines all 46 of your chromosomes under a microscope. It’s done from a blood sample and can detect large structural rearrangements - such as a translocation (where two chromosomes have swapped pieces) or an inversion (where a segment has flipped around).

If a parent carries a balanced rearrangement, they usually have no symptoms themselves, but their eggs or sperm may end up with an unbalanced set of chromosomes, leading to miscarriage or, less often, a baby with developmental problems. Knowing about a rearrangement helps you understand your risk and consider options like in vitro fertilisation (IVF) with genetic testing of embryos before transfer.

Karyotype testing is often recommended for couples after two or three miscarriages, depending on local guidelines and other factors. Your GP or specialist can refer you for this on the NHS, though waiting times vary.

Carrier screening for inherited conditions

Some couples also consider carrier screening - testing to see if they carry gene changes for recessive or X-linked conditions. If both partners are carriers for the same recessive condition, there’s a 1-in-4 chance with each pregnancy that the baby will inherit two copies and be affected. Most recessive conditions don’t cause miscarriage, but they can lead to serious illness in a baby or child.

Carrier screening is not routinely offered as part of a miscarriage workup, but some couples choose it - particularly if they have a family history of genetic conditions, if they’re from communities where certain conditions are more common, or if they want comprehensive information before trying again.

When genetic factors aren’t the answer

It’s important to know that genetic testing doesn’t always provide an explanation. The standard NHS workup for recurrent miscarriage - which includes blood tests, scans, and sometimes further investigations - identifies a potential cause in under half of cases. Even when testing the pregnancy tissue and the parents’ chromosomes, many couples still don’t get a definitive answer.

Other factors that can contribute to recurrent miscarriage include:

• Antiphospholipid syndrome - an immune condition that increases clotting risk
• Uterine abnormalities - structural problems with the womb
• Hormonal imbalances - such as uncontrolled thyroid disease or diabetes
• Cervical weakness - where the cervix opens too early in pregnancy

Your doctor will usually test for these as part of the overall assessment.

Even without a clear cause, many couples go on to have a successful pregnancy. The outlook is often better than it feels in the moment.

What happens after testing

If testing reveals a chromosomal rearrangement in one of you, your doctor will refer you to a genetic counsellor or clinical genetics specialist. They can explain:

• What the rearrangement means for future pregnancies
• The chance of having a baby with an unbalanced chromosome set
• Whether other family members might be affected
• Options such as IVF with preimplantation genetic testing, where embryos are tested before transfer
• Prenatal testing during pregnancy (such as chorionic villus sampling or amniocentesis)

If pregnancy tissue testing shows a chromosomal problem that arose by chance, the genetic counsellor can reassure you that it’s not inherited and doesn’t necessarily increase your risk next time - though age-related risks still apply.

If carrier screening reveals that you’re both carriers for the same condition, you’ll be offered genetic counselling to discuss the implications and your options, which may include IVF with embryo testing, prenatal diagnosis, or proceeding without intervention and testing the baby after birth.

What you can do at Jeen

Jeen offers genetic testing that can help couples investigating recurrent miscarriage understand the chromosomal and genetic factors that may be contributing.

Karyotype Chromosome Analysis examines all 46 of your chromosomes at a detailed level, detecting numerical changes and large structural rearrangements such as translocations or inversions. This test is useful if you’re investigating recurrent miscarriage or fertility issues and want to know whether a chromosomal rearrangement might be playing a role. It requires a blood draw, and 30-minute genetic counselling is included to help you understand the results.

For couples who want a comprehensive genetic work-up before trying to conceive again, the Carrier Screening + Karyotype bundle combines chromosome-level karyotype analysis with screening for 1,008 genes associated with inherited recessive conditions. It’s a complete pre-conception package: one blood draw, one 30-minute genetic counselling session covering both tests, and one integrated report. You’ll save £80 (single) or £130 (couple) compared to ordering the tests separately.

If you’re primarily interested in understanding your carrier status - particularly if you have a family history of genetic conditions or are from a community where certain conditions are more common - Carrier Screening on its own may be the right choice. It screens 1,008 genes, includes 30-minute genetic counselling, and uses NHS Genomic Medicine Service-aligned variant interpretation. An at-home buccal swab is included, or you can opt for an in-clinic blood draw. Results are typically available within 17-21 working days of the laboratory receiving your sample.

These tests complement - but don’t replace - the NHS recurrent miscarriage workup, which includes blood tests for clotting disorders, hormone levels, and scans of your uterus. Jeen’s testing focuses specifically on the genetic and chromosomal factors, providing detailed information that can help you and your healthcare team make informed decisions about future pregnancies.