Among the cultural narratives around IVF in India, twins are frequently presented as a desirable outcome — a bonus, a sign of success, proof that the treatment worked abundantly. Couples who have struggled with infertility sometimes arrive at their first consultation actively hoping for twins — two children from one treatment cycle, completing the family in a single successful attempt.

This cultural expectation deserves a direct, honest clinical response. Twins from IVF — and higher-order multiples — are not a bonus. They are a complication. They represent a specific, well-documented pattern of obstetric and neonatal risk that affects both mother and babies, and the reduction of multiple pregnancy rates in IVF is not a matter of clinical preference or conservative practice philosophy — it is a matter of patient safety.

Understanding the risks associated with multiple pregnancy — and understanding why the clinical practice of single embryo transfer has become the standard recommendation for most IVF patients — is essential for couples approaching IVF with accurate expectations and appropriate clinical priorities.

This article provides that understanding completely and honestly. The risks are real. The solution — single embryo transfer — is effective. And the evidence that single embryo transfer combined with frozen transfer strategy produces comparable cumulative live birth rates to double embryo transfer, without the multiple pregnancy risk, is both compelling and clinically important.

The Historical Context: Why Multiple Pregnancy Became Associated With IVF

Multiple pregnancy rates are higher in IVF than in natural conception — and understanding why requires understanding the historical development of IVF practice.

In the early decades of IVF — from its development in the 1970s through the 1990s — the technology of embryo culture, cryopreservation, and embryo selection was significantly less reliable than it is today. Embryos cultured to day two or three had lower implantation potential per embryo than modern blastocyst-culture embryos. Cryopreservation technology was less effective — frozen embryo survival rates and post-thaw quality were substantially lower than with modern vitrification.

In this context, transferring two, three, or more embryos in a single fresh cycle was the rational clinical response to the low individual implantation probability of each embryo. If each embryo had a ten to fifteen percent chance of implanting, transferring three embryos produced an acceptable overall cycle success rate while accepting the risk that all three might implant simultaneously.

The consequences were predictable and documented across global IVF registries. IVF was responsible for a dramatically elevated rate of twin and higher-order multiple pregnancies compared to naturally conceived pregnancies. In the 1990s and early 2000s, twin rates from IVF in some countries approached 30 to 35 percent of all IVF births.

Over the same period, the clinical literature on the risks of multiple pregnancy became increasingly alarming — as the outcomes of the elevated multiple birth rates produced by IVF were systematically studied and the magnitude of the associated risks became clear.

The Risks of Twin and Multiple Pregnancy — The Complete Clinical Picture

The risks associated with multiple pregnancy from IVF are documented, substantial, and affect both the mother and the babies. They deserve to be understood in full.

Risks to the Mother

Preterm labour and complications of prematurity management. Twin pregnancies have a substantially elevated rate of preterm labour. The management of preterm labour — including hospital admission, tocolytic medications to delay delivery, antenatal corticosteroids to accelerate fetal lung maturity — is medically intensive and emotionally exhausting.

Pre-eclampsia. The rate of pre-eclampsia — a potentially life-threatening condition of pregnancy involving elevated blood pressure, proteinuria, and end-organ dysfunction — is significantly higher in twin pregnancies than in singleton pregnancies. Pre-eclampsia requiring delivery before term is a major contributor to the prematurity associated with multiple pregnancy.

Gestational diabetes. Twin pregnancies have higher rates of gestational diabetes, requiring dietary management and in some cases insulin therapy.

Anaemia. The nutritional demands of a multiple pregnancy are substantially greater, and iron deficiency anaemia is more common and more severe in multiple pregnancies.

Caesarean section. The rate of caesarean delivery in twin pregnancies is substantially higher than in singleton pregnancies — related to malpresentation (one or both babies in an unfavorable position for vaginal delivery), preterm delivery at gestational ages where caesarean is preferred, and the technical complexity of delivering the second twin vaginally after the first.

Postpartum haemorrhage. The risk of significant postpartum bleeding is elevated in twin pregnancies — related to the larger placental surface area and the greater uterine distension.

Maternal mortality. In absolute terms, multiple pregnancy carries a higher maternal mortality risk than singleton pregnancy — reflecting the cumulative effect of the elevated rates of each of the obstetric complications described above.

Risks to the Babies

Prematurity. The most significant risk to twins and higher-order multiples from IVF is preterm birth — delivery before 37 weeks of gestation. The median gestational age at delivery for twins is approximately 35 to 36 weeks — significantly preterm compared to the 39 to 40 weeks of a singleton. Triplets deliver at approximately 32 to 33 weeks.

The consequences of prematurity are well-documented and extend across the full spectrum of gestational age. Babies born at 35 to 36 weeks — late preterm — have higher rates of respiratory distress, feeding difficulties, jaundice, and hypoglycaemia than babies born at term. Babies born at 28 to 32 weeks — very preterm — require intensive neonatal care, face substantially elevated rates of serious morbidity including intraventricular haemorrhage, necrotising enterocolitis, and bronchopulmonary dysplasia, and carry elevated long-term risk of neurodevelopmental impairment.

Low birthweight. Independent of gestational age, twins have lower average birthweights than singletons — reflecting the competitive sharing of placental resources between two growing fetuses.

Twin-to-twin transfusion syndrome (TTTS). In monochorionic twin pregnancies — where both twins share a single placenta — abnormal vascular connections between the twins' circulations can cause a serious condition in which one twin receives too much blood and the other too little. TTTS requires specialist fetal medicine management and carries significant risk to both twins.

Neonatal intensive care admission. The combination of prematurity and low birthweight means that a significant proportion of twins — and the majority of triplets — require neonatal intensive care admission at birth, with all the emotional, logistical, and financial demands this entails.

Long-term neurodevelopmental outcomes. Prematurity is the single most important risk factor for cerebral palsy, developmental delay, and school-age learning difficulties. Twin pregnancies, by virtue of their elevated prematurity rates, carry elevated long-term neurodevelopmental risk compared to singleton pregnancies.

The Solution: Single Embryo Transfer

The clinical solution to the multiple pregnancy risk of IVF is single embryo transfer — the practice of transferring one embryo per cycle, selecting the single best-quality embryo available and deferring any remaining good-quality embryos to future frozen transfer cycles.

The development and adoption of single embryo transfer (SET) was made clinically feasible by two technological advances that have occurred in parallel with the growing understanding of multiple pregnancy risks.

Blastocyst culture. The ability to culture embryos reliably to the blastocyst stage — day five or six — allows the natural selection process of embryo development to operate before transfer, identifying embryos of sufficient developmental competence to reach this advanced stage. Blastocysts have significantly higher individual implantation potential than day-three embryos — approximately 40 to 50 percent per blastocyst in favorable prognosis patients, compared to fifteen to twenty percent for a day-three embryo. This higher individual implantation rate means that a single blastocyst transfer produces an overall cycle success rate comparable to transferring two day-three embryos — without the multiple pregnancy risk.

Vitrification. The development of vitrification — the rapid-freeze cryopreservation technique — produced frozen embryo survival rates of ninety to ninety-five percent or above, making frozen transfer cycles highly reliable. This means that additional good-quality blastocysts from a stimulation cycle can be frozen with confidence that they will survive thawing and be available for future transfer. The couple does not lose their "spare" embryos by deferring them — they preserve them for subsequent attempts.

PGT-A. The availability of preimplantation genetic testing allows chromosomal selection of the single embryo most likely to implant and least likely to miscarry — further improving the implantation probability of SET and reducing the miscarriage risk.

Together, these technologies have made elective single embryo transfer — SET — the clinically appropriate standard for most IVF patients. The question is no longer whether the implantation probability of a single embryo is high enough to justify transferring only one. It is.

Does SET Reduce Overall IVF Success? The Cumulative Rate Evidence

The most common concern raised about single embryo transfer is that it reduces success rates — that couples who transfer only one embryo will have lower overall success than those who transfer two.

This concern misunderstands the relevant comparison. The relevant comparison is not per-cycle success from SET versus per-cycle success from double embryo transfer (DET). It is cumulative success across multiple attempts.

The cumulative evidence is clear and compelling. Multiple well-designed studies and randomised controlled trials have demonstrated that the cumulative live birth rate from a single stimulation cycle — one fresh SET followed by frozen SET cycles using the remaining embryos — is equivalent to or not significantly lower than the cumulative live birth rate from double embryo transfer in the same stimulation cycle.

The clinical mathematics are straightforward. If a stimulation cycle produces three good-quality blastocysts, and they are all transferred two at a time across two cycles, the total opportunity for success is two cycles — with the risk that both embryos in the first transfer implant simultaneously. If the same three embryos are transferred one at a time across three cycles, the total opportunity for success is three cycles — with no risk of multiple pregnancy. The cumulative probability of at least one success is comparable or higher with sequential SET, and the risk of multiple pregnancy is essentially eliminated.

The twins that result from a double embryo transfer do not represent more success than a singleton pregnancy — they represent two simultaneous successes at the cost of substantially elevated obstetric and neonatal risk. The singleton pregnancy from a single embryo transfer, followed by a subsequent singleton pregnancy from a frozen transfer, represents the same reproductive outcome — two children — without the risks of multiple pregnancy for either mother or babies.

When Double Embryo Transfer May Be Considered

While SET is the appropriate standard for most patients, there are specific clinical circumstances in which transferring two embryos may be considered after an individualized discussion of the risks and benefits.

Older patients with poor prognosis and limited embryo availability. For a woman over 40 with very few embryos produced from a stimulation cycle — where the individual implantation probability of each embryo is low and the number of future transfer opportunities is limited — the benefit-risk calculation for double transfer shifts. The probability of both embryos implanting is lower in this age group, and the urgency of achieving a pregnancy in the available treatment window is greater.

Repeated implantation failure after multiple single transfers. When multiple consecutive single embryo transfers of apparently good-quality embryos have failed, the clinical picture may suggest an implantation problem that warrants a different approach. In this specific circumstance — after thorough investigation has not revealed a correctable uterine or immunological cause — double embryo transfer may be considered as part of a revised strategy.

The couple's own fully informed preference. After a complete discussion of the specific risks of multiple pregnancy and the cumulative success data for sequential SET, some couples — particularly those who have been through many years of infertility and who place very high value on the possibility of twins specifically — may express a preference for double transfer. This preference deserves to be heard, respected as their autonomous decision, and supported by a genuinely complete discussion of what the risks involve — not just acknowledged and accommodated without engagement.

In all of these circumstances, the recommendation from Metro IVF is the same: the decision is made after an individualized conversation specific to this couple's clinical picture, not as a default policy applied to all patients who request it.

The Specific Risk of Spontaneous Splitting — Identical Twins from SET

One clinical reality that couples who pursue single embryo transfer should be aware of is that a small proportion of blastocyst transfers result in monozygotic twins — identical twins arising from spontaneous splitting of the transferred embryo after it enters the uterus.

The rate of monozygotic twinning from blastocyst single embryo transfer is approximately two to three percent — higher than the background rate from natural conception of approximately one percent, for reasons that are not fully understood but may relate to the laboratory culture conditions or the zona manipulation involved in embryo handling.

Monozygotic twins from SET are entirely outside the clinical team's control — they represent the embryo's own spontaneous splitting rather than any decision about how many embryos to transfer. Their occurrence is not a failure of the SET strategy. But couples undergoing SET should be informed that a small residual twin rate exists even from single embryo transfer.

The Metro IVF Approach to Embryo Transfer

At Metro IVF in Ambikapur, the standard recommendation for embryo transfer is elective single embryo transfer — one blastocyst per transfer, with additional good-quality blastocysts cryopreserved for subsequent frozen transfer cycles.

This recommendation is made not because it is a policy of conservative practice or risk aversion — but because the cumulative live birth rate evidence and the multiple pregnancy risk evidence together make it the approach that gives the couple the best overall reproductive outcome while protecting the health of the mother and the babies.

The conversation about this recommendation is a clinical conversation — specific to each couple's embryo quality, their age, their history, their clinical picture, and their own values and preferences. It is a conversation in which the evidence is shared, the risks are explained, and the couple's questions are answered before a plan is made.

For couples who arrive at Metro IVF hoping for twins from IVF, Dr. Soni has this conversation honestly and compassionately — acknowledging the appeal of the hope, explaining the clinical reality of the risks, and offering the sequential SET approach as the path that most reliably delivers what the couple actually wants: healthy children.

Your Next Step

If you are considering IVF and want to understand the approach to embryo transfer that gives you the best overall reproductive outcome with the lowest risk — or if you have been offered double embryo transfer elsewhere and want an honest assessment of whether it is the right recommendation for your specific situation — a consultation with Dr. Ashish Soni at Metro IVF in Ambikapur provides the most complete and honest clinical guidance available.

The goal of IVF is a healthy baby. Single embryo transfer is the approach that best serves that goal for most patients.

Metro IVF Test Tube Baby Center Ambikapur, Chhattisgarh metrofertility.in Led by Dr. Ashish Soni — North India's First Fertility Super Specialist

The goal is a healthy baby — not twins. Book your consultation with Dr. Ashish Soni at Metro IVF today.