Recurrent Pregnancy Loss After IVF and the Role of Genetic Testing

Some couples go through IVF, achieve a pregnancy and then lose it, sometimes more than once. When this happens, the question is not only how to try again but why the losses are happening. This article uses an anonymised, simplified example from clinical practice to explain how genetic testing of the couple and of their embryos can help answer that question.

When IVF Pregnancies Keep Ending Early

Consider a couple in their late thirties who have been trying to conceive for several years. IVF produces good-quality blastocysts, which are frozen by vitrification. Transfers lead to pregnancies, but these end in late miscarriage or preterm loss. On medical advice, a gestational surrogate is then considered, yet the pregnancies still fail.

A pattern like this suggests that the problem may lie with the embryos rather than with the uterus or the IVF process itself.

Testing the Pregnancy Tissue and the Couple

When a pregnancy is lost, the pregnancy tissue can be sent for chromosomal analysis. If it shows a chromosomal abnormality, the next step is usually karyotyping of both partners, a blood test that looks at the number and structure of their chromosomes.

In some couples, one partner carries a balanced structural change, such as an inversion or a translocation. The carrier is usually healthy, but some of their eggs or sperm carry an unbalanced set of chromosomes. Embryos made from these can fail to implant or can lead to miscarriage.

How Preimplantation Genetic Testing Helps

Preimplantation genetic testing for aneuploidy (PGT-A, previously called PGS) checks a few cells from each blastocyst for the correct number of chromosomes. Where a parent carries a structural change, testing for structural rearrangements (PGT-SR) may be advised. Embryos that test normal can then be chosen for transfer.

Testing can lower the chance of transferring an embryo that is unlikely to develop, but it has limits. It does not ensure implantation, pregnancy or a healthy baby, a result can occasionally be misleading because of mosaicism, and some couples find that few or none of their embryos test normal.

The Role of Embryo Freezing

Vitrification allows embryos from one or more IVF cycles to be stored while tests and investigations are carried out. Embryos can then be tested and transferred one at a time, which also avoids the risks of a multiple pregnancy.

Questions to Ask Your Fertility Team

• Has the tissue from any pregnancy loss been tested for chromosomal problems?
• Should both partners have a karyotype test?
• Would PGT-A or PGT-SR be useful for our embryos, and what are its limits?
• Are there other causes to check, such as uterine, hormonal, clotting or immune factors?

Recurrent pregnancy loss is distressing, and every couple's situation is different. If you would like an independent explanation of your IVF and embryology reports, you can book a consultation with Goral Gandhi.