Introduction: A Very Common Misconception
One of the most common assumptions couples make when considering IVF is that it automatically results in twins. It is easy to see why — many high-profile stories about IVF involve multiple births, and the association has become deeply embedded in public perception.
The reality is more nuanced—and much more reassuring. At PSFC OMR, Chennai, we want to clarify exactly how IVF and multiple pregnancies are related and what modern practice does to ensure the safest possible outcomes for mothers and babies.
Why Did IVF Used to Result in More Twins?
In the early decades of IVF, success rates per embryo were significantly lower than they are today. To improve the chances of at least one embryo implanting, clinics routinely transferred two, three, or even more embryos per cycle. This strategy worked — but it came with a cost: multiple pregnancies became common.
As laboratory technology, embryo culture methods, and embryo selection improved, the success rates of individual embryo transfers improved dramatically. The need to transfer multiple embryos to achieve success has diminished, and the practice has shifted accordingly.
What Modern IVF Practice Actually Looks Like
Single Embryo Transfer (SET) Is Now the Global Standard
Most leading fertility centers worldwide—including PSFC OMR, Chennai—now recommend elective single embryo transfer (eSET) for eligible patients. This means transferring one carefully selected embryo per cycle, rather than two or more.
The reasons are clear:
- Twin and higher-order pregnancies carry significantly higher risks for both mother and babies.
- Modern embryo selection—including time-lapse monitoring and Preimplantation Genetic Testing (PGT) — allows clinicians to identify the single best embryo with high confidence.
- Remaining high-quality embryos can be vitrified (frozen) for future cycles, meaning no embryo is wasted.
What Are the Risks of Multiple Pregnancies?
Twin and triplet pregnancies are categorised as high-risk for good reason:
| Risk | Singleton Pregnancy | Twin Pregnancy |
| Premature birth (before 37 weeks) | ~10% | ~60% |
| Low birth weight | Less common | ~50% of twins |
| Gestational diabetes | Moderate risk | Significantly higher risk |
| Pre-eclampsia | Moderate risk | 2–3x higher risk |
| Caesarean section | Variable | Very common |
| NICU admission | Less likely | More likely |
These risks are not to discourage couples who do have twins — many twin pregnancies result in healthy babies. But they underscore why modern IVF deliberately avoids multiple embryo transfers wherever possible.
When Can Twins Still Occur in IVF?
Even with single embryo transfer, there is a small chance of twins. This happens when a transferred embryo spontaneously divides, resulting in identical (monozygotic) twins — a process that occurs naturally and is not caused by the IVF procedure itself. This probability is slightly higher with IVF blastocysts than in natural conception, occurring in approximately 1–3% of SET cycles.
Additionally, some patients — often in consultation with their specialist — may choose to transfer two embryos when the clinical situation supports it, such as in older patients with reduced embryo quality and limited embryo numbers, or after repeated failed single embryo transfer cycles.
How Embryos Are Selected for Transfer
The key to successful single embryo transfer is selecting the right embryo. At PSFC OMR, Chennai, embryo selection involves:
- Blastocyst culture (developing embryos to day 5–6 for maximum viability assessment)
- Time-lapse imaging to monitor embryo development continuously
- AI-assisted embryo grading for objective assessment
- Preimplantation Genetic Testing (PGT-A) where indicated, to select chromosomally normal embryos
This multi-layered selection process means the single embryo transferred has been chosen with the highest possible level of scientific confidence.
IVF Success Rates with Single Embryo Transfer
| Age Group | Approx. Live Birth Rate per SET | With PGT-Tested Embryo |
| Under 35 | 45–55% | 60–65% |
| 35–37 | 35–45% | 50–60% |
| 38–40 | 25–35% | 40–50% |
| 41–42 | 15–25% | 30–40% |
💡 Tip: Cumulative success rates — accounting for all frozen embryos from a single stimulation cycle — are even higher. Many couples achieve pregnancy across multiple transfers from one egg collection.
What If Couples Want Twins?
Some couples specifically request twins, viewing it as an efficient way to complete their family in one pregnancy. While we understand this reasoning, our specialists explain the medical realities clearly: the risks to mother and babies are genuinely elevated, and the best outcome for your family is a healthy singleton pregnancy followed by another frozen embryo transfer if desired.
At PSFC OMR, Chennai, we prioritise the safety and wellbeing of both mother and child — and our embryo transfer recommendations always reflect this commitment.
Conclusion
IVF does not automatically result in twins. Modern IVF practice—guided by improved technology, better embryo selection, and a strong commitment to maternal and infant safety—actively prioritizes single embryo transfer and singleton pregnancies. Twins from IVF are now the exception, not the rule.
One healthy baby, born safely, is always the goal. With the right embryo, transferred at the right time, that is exactly what modern IVF is designed to achieve.
FAQs
Is it possible to request twin transfer in IVF?
You can discuss your preferences with your specialist. However, your clinical team will advise based on your specific case — most centres will recommend eSET for safety reasons.
