Course / How Many Embryos to Transfer?
Modern fertility medicine has evolved significantly. In earlier years, transferring two or more embryos was common practice to increase pregnancy rates. However, with today’s advanced laboratory technology, improved embryo culture systems, and genetic testing (PGT-A), a single high-quality embryo transfer (SET) can achieve equal or better success rates while minimizing risk.
Key determinants in deciding how many embryos to transfer include:
Embryo quality and developmental stage
Maternal or gestational carrier age
Use of preimplantation genetic testing (PGT-A)
Previous transfer outcomes
Endometrial receptivity and hormonal synchronization
Clinic-specific success metrics and ASRM guidelines
At Surrogacy4All, every case is assessed individually to optimize both success and safety for intended parents and gestational carriers.
Transferring multiple embryos may appear to increase chances of pregnancy, but it also significantly raises the risk of multiple gestations — twins, triplets, or more — which carry serious medical risks.
Maternal & Gestational Carrier Risks:
Higher incidence of preterm birth
Increased cesarean section rates
Gestational diabetes, hypertension, and preeclampsia
Greater risk of placental complications and postpartum hemorrhage
Fetal Risks:
Low birth weight
Increased NICU admissions
Developmental delays or long-term health complications
Surrogacy-Specific Considerations:
In gestational surrogacy, agencies like Surrogacy4All follow strict ethical and medical protocols. Transferring more than one embryo exposes both the surrogate and the babies to unnecessary risk. Therefore, single embryo transfer (SET) is generally preferred unless strong medical justification exists.
While modern guidelines favor single transfers, certain clinical scenarios may still warrant the transfer of two embryos.
Potential benefits (in specific, controlled cases):
May slightly increase per-cycle pregnancy probability in older women or those with lower-quality embryos.
Can be considered for patients without PGT-A-tested embryos, where embryo genetic health is uncertain.
However, even in these cases, the overall live birth rate per embryo does not necessarily improve, and the associated medical risks often outweigh the potential benefit.
After an unsuccessful single embryo transfer, intended parents may request transferring multiple embryos in the next cycle.
Before making that decision, fertility experts evaluate:
Embryo quality and ploidy status
Uterine lining receptivity (ERA results, endometrial thickness)
Hormone levels and synchronization issues
Lab and catheter transfer conditions
In many cases, the cause of a failed transfer is not the number of embryos, but rather biological timing or uterine receptivity.
If all diagnostic parameters are normal, continuing with single embryo transfer — especially using PGT-A tested blastocysts — remains the safest and most effective strategy.
Embryos can be transferred on Day 3 (cleavage stage) or Day 5/6 (blastocyst stage).
This timing can influence how many embryos are typically considered for transfer.
Day 3 embryos: Because they are less developed, historically more than one was transferred to increase chances.
Day 5 embryos (blastocysts): Have undergone natural selection in culture — only the strongest embryos reach this stage. As a result, a single Day 5 transfer is often sufficient and preferred.
Most modern IVF and surrogacy programs — including Surrogacy4All’s medical partners — rely on Day 5 blastocyst transfers, which align with higher implantation predictability and lower risk.
The American Society for Reproductive Medicine (ASRM) provides evidence-based guidelines that fertility centers and agencies like Surrogacy4All follow closely.
| Patient / Surrogate Profile | Embryo Type | Recommended Number to Transfer |
|---|---|---|
| Age <35, PGT-A Normal | Blastocyst (Day 5/6) | 1 |
| Age <35, Unscreened Embryos | Blastocyst (Day 5/6) | 1–2 (prefer 1) |
| Age 35–37 | PGT-A Normal | 1 |
| Age 38–40 | PGT-A Normal | 1–2 (case-dependent) |
| Age >40 | PGT-A Normal or Unscreened | 2 |
| Gestational Surrogacy (all ages) | Any | 1 |
These recommendations are designed to minimize multiple gestation risks while maintaining strong success rates.
At Surrogacy4All, adherence to ASRM and FDA guidelines is non-negotiable for patient and surrogate safety.
At first glance, transferring more embryos may seem cost-effective — one transfer, higher chance of success. However, the long-term financial implications of multiple gestations can be substantial.
Single Embryo Transfer (SET):
Slightly higher chance of needing multiple transfer cycles
Lower overall medical cost, fewer complications
Lower risk of NICU admissions and preterm care expenses
Multiple Embryo Transfer:
Higher chance of early success, but:
Increased prenatal care costs
Greater risk of bed rest, hospitalization, or preterm birth
Additional delivery and neonatal costs
Increased emotional and logistical strain on surrogate and intended parents
Ultimately, SET tends to be more cost-effective and safer when viewed through a full medical and ethical lens.
This is a collaborative medical decision — made between the:
Fertility specialist or reproductive endocrinologist
Embryologist
Gestational carrier (if applicable)
Intended parents
Agency’s clinical oversight team
At Surrogacy4All, this decision is made only after full informed consent and review of:
ASRM guidelines
Clinic policy
Surrogate’s health profile
Ethical and legal considerations
Our mission is to ensure every transfer maximizes success without compromising safety for the surrogate or the developing embryos.
Trust the science. With advanced culture systems and PGT-A, one healthy blastocyst can lead to an excellent success rate.
Quality over quantity. The number of embryos does not equal higher success — embryo health and uterine readiness are what matter most.
Safety first. Protecting the gestational carrier’s health and avoiding complications is always the top priority.
Communicate openly. Intended parents should feel empowered to ask questions and understand the rationale behind medical recommendations.
Think long-term. A single healthy pregnancy leads to a better outcome — physically, emotionally, and financially — for everyone involved.
Our job is to listen, to connect the dots between your needs, and to determine how we can best help you have your baby. If you’re asking how much does it cost for a surrogate, we’ll walk you through every step of the process to ensure there are no surprises.
To make an appointment with one of our counselors or physicians, please call (212) 661-7673 or email info@surrogacy4all.com. We look forward to hearing from you.
Surrogacy4All is a unique international surrogacy service targeted at providing state of the art IVF and surrogacy services to Intended Parents irrespective of age, sex or color, at the lowest possible cost in the world.
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