Senior Consultant, Medical Genetics, Artemis Hospitals, Gurgaon, India
Part 3 of 12 in Finding Answers in Recurrent Pregnancy Loss
Balanced Translocation: When a Genetically Normal Parent Passes on Recurrent Loss
June 7, 2026
About 1 in 600 people in the general population carry a balanced translocation (all their chromosomal material is present, just rearranged between two chromosomes) with no health impact on the carrier themselves. The risk surfaces during meiosis, when the chromosomes must separate to form eggs or sperm: this can produce gametes with a normal complement, a balanced translocation, or an unbalanced one, and it's the unbalanced gametes that lead to chromosomally abnormal embryos. Balanced translocation affects around 7% of couples with recurrent pregnancy loss, particularly first-trimester cases.
The most common form is Robertsonian translocation, involving chromosomes 13, 14, 15, 21 or 22: carriers still have roughly a 70% chance of a normal child, with about 30% risk of either recurrent loss or a child with a disability or birth defect. There's one critical exception: the 21/21 Robertsonian translocation carries a 100% recurrence risk of trisomy 21 in every pregnancy, ruling out both prenatal diagnosis and PGT as viable paths; these couples need a donor gamete. For everyone else, options include natural conception with prenatal testing, IVF with PGT for structural rearrangements (PGT-SR), or donor gametes.
This guide is based on a live Jivo Masterclass — Dr. Kanika Singh taught doctors across Africa on June 7, 2026.
FROM THE LIVE Q&A
Dr. Isaya
My question is about sperm collection. In my clinic I often see couples where the male is over 50 years old. What are the chances of getting good quality sperm, and what are the implications for implantation?
Dr. Kanika Singh
I will not be able to give you details about specific sperm selection procedures, as in our hospital this is a multidisciplinary process involving the IVF specialist and the andrology laboratory. But in terms of the genetic implications: above the age of 50, there is a high chance that sperm quality is reduced, and the sperm DNA fragmentation index is likely to be elevated. Unless we specifically test for it, we do not know the exact level, but even without testing, there is a significant chance that sperm DNA quality is impaired, which can result in recurrent pregnancy loss or implantation failure. Testing the sperm DNA fragmentation index in men above 50 with a history of recurrent pregnancy loss or implantation failure would be worthwhile.
Frequently Asked Questions
For patients with PCOS, how long should metformin be taken before conception and after conception?▼
Metformin should be started at least 2 to 3 months before conception. It is safe to continue in pregnancy and is generally continued through the first trimester and sometimes beyond. It should be monitored with GTT as well as regular HbA1c and blood sugar checks throughout.
My question is about sperm collection. In my clinic I often see couples where the male is over 50 years old. What are the chances of getting good quality sperm, and what are the implications for implantation?▼
I will not be able to give you details about specific sperm selection procedures, as in our hospital this is a multidisciplinary process involving the IVF specialist and the andrology laboratory. But in terms of the genetic implications: above the age of 50, there is a high chance that sperm quality is reduced, and the sperm DNA fragmentation index is likely to be elevated. Unless we specifically test for it, we do not know the exact level, but even without testing, there is a significant chance that sperm DNA quality is impaired, which can result in recurrent pregnancy loss or implantation failure. Testing the sperm DNA fragmentation index in men above 50 with a history of recurrent pregnancy loss or implantation failure would be worthwhile.
What is a balanced translocation and how common is it?▼
About 1 in 600 people in the general population carry a balanced translocation, meaning all their chromosomal material is present but rearranged between two chromosomes, with no health impact on the carrier.
How does a balanced translocation lead to pregnancy loss?▼
The risk surfaces during meiosis, when chromosomes must separate to form eggs or sperm; this can produce gametes with a normal complement, a balanced translocation, or an unbalanced one, and it is the unbalanced gametes that lead to chromosomally abnormal embryos.
What proportion of recurrent pregnancy loss couples carry a balanced translocation?▼
Balanced translocation affects around 7% of couples with recurrent pregnancy loss, particularly first-trimester cases.
What is the outlook for couples with a Robertsonian translocation?▼
Carriers still have roughly a 70% chance of a normal child, with about a 30% risk of either recurrent loss or a child with a disability or birth defect.
Is there a translocation with a guaranteed recurrence risk?▼
Yes. The 21/21 Robertsonian translocation carries a 100% recurrence risk of trisomy 21 in every pregnancy, ruling out both prenatal diagnosis and PGT; these couples need a donor gamete.
In This Series: Finding Answers in Recurrent Pregnancy Loss
- 1.Finding Answers in Recurrent Pregnancy Loss
- 2.Fetal Chromosomal Abnormalities: The Leading Cause of First-Trimester Loss
- 3.Balanced Translocation: When a Genetically Normal Parent Passes on Recurrent Loss
- 4.Single-Gene Causes: Why Second-Trimester Losses Need a Different Genetic Workup
- 5.Anatomical Causes: Uterine Septum, Fibroids, and Cervical Incompetence
- 6.Antiphospholipid Antibody Syndrome: Diagnosis and Treatment
- 7.Endocrine Causes: Thyroid, PCOS, and Diabetes in Recurrent Pregnancy Loss
- 8.Sperm DNA Fragmentation: The Male Factor in Recurrent Pregnancy Loss
- 9.The Immunological Debate: NK Cells, TNF-Alpha, and IVIG Therapy
- 10.What to Test For: A Practical Investigation Framework by Trimester
- 11.Pre-Implantation Genetic Testing: PGT-A, PGT-M, PGT-SR and PGT-HLA Explained
- 12.Prognosis After Recurrent Pregnancy Loss: Why the Outlook Is Better Than Most Couples Expect