6.13 Embryo Splitting in Surrogacy: A Rare but Exciting Possibility

In some IVF and surrogacy journeys, a single embryo may naturally split into two, resulting in identical twins. This is a rare but exciting event, bringing the possibility of welcoming two babies instead of one. While this phenomenon introduces additional medical considerations, the vast majority of twin pregnancies at GSHC Surrogacy result in happy, healthy outcomes with proper medical care and monitoring.

At GSHC Surrogacy, we have seen that most surrogates are open to carrying twins if an embryo splits, as long as the medical team confirms it is safe. Through careful preparation, expert medical guidance, and open communication between intended parents and surrogates, the surrogacy journey remains smooth and positive.

1. The Likelihood of an Embryo Splitting in IVF

While embryo splitting can happen naturally, it is a rare event in IVF pregnancies, occurring in only 1-2% of casescompared to 0.4% in natural conception (Hershlag et al., 1999; Blickstein et al., 2003).

Factors That May Increase the Chance of Splitting:

✔ Day 5 blastocysts (more developed embryos) are slightly more likely to split than earlier-stage embryos (Kanter et al., 2023).

✔ Assisted hatching (a lab technique used in some IVF procedures) may increase the likelihood of embryo splitting (Pfeifer et al., 2012).

✔ This is a natural event, not caused by IVF itself, meaning it can happen in both natural and IVF pregnancies (Hall, 2003).

💡 Since embryo splitting is rare, many intended parents view it as a unique and special occurrence rather than a complication.

2. Do Identical Twins Share a Placenta? Understanding Chorionicity

When an embryo splits, whether the resulting twins share or have separate placentas depends on when the split occursafter fertilization.

Timing of Split	Twin Type	Placentas (Chorionicity)	Amniotic Sacs (Amnionicity)	Common in IVF?
Day 1-3 (Very Early Split)	Dichorionic-Diamniotic (Di-Di) Twins	Two Placentas (Separate)	Two Amniotic Sacs	Rare
Day 4-8	Monochorionic-Diamniotic (Mo-Di) Twins	One Shared Placenta	Two Amniotic Sacs	Most Common in IVF
Day 8-13	Monochorionic-Monoamniotic (Mo-Mo) Twins	One Shared Placenta	One Shared Amniotic Sac	Rare, Requires Closer Monitoring
After Day 13	Conjoined Twins	One Shared Placenta	One Shared Sac	Extremely Rare

💡 Most identical twins from IVF split between days 4-8, meaning they will share a placenta but have separate amniotic sacs (Mo-Di twins) (Hack et al., 2005).

3. Ensuring a Smooth Twin Pregnancy with GSHC Surrogacy

At GSHC Surrogacy, we have helped many intended parents and surrogates navigate twin pregnancies with great success. Through expert medical care, proper monitoring, and strong communication, most of our twin pregnancies result in healthy deliveries and happy families.

Key Considerations for a Successful Twin Pregnancy:

✔ Enhanced medical care – Twin pregnancies require more frequent monitoring to ensure both babies are growing properly (American College of Obstetricians and Gynecologists, 2021).

✔ Open communication – Intended parents and surrogates discuss expectations regarding twin pregnancies before matching.

✔ Healthy pregnancy planning – Surrogates carrying twins may require additional nutritional support and adjusted activity levels (Goldenberg et al., 2008).

💡 While twin pregnancies require additional care, most GSHC Surrogacy families experience positive and fulfilling outcomes.

4. Addressing Twin Pregnancies in Surrogacy Contracts

Because embryo splitting is unexpected, it is crucial to discuss all possibilities before matching. At GSHC Surrogacy, we ensure that both intended parents and surrogates are aligned before signing the surrogacy contract, so every possibility—including twins—is handled with clarity and confidence.

What Is Included in the Contract?

✔ Surrogate’s Willingness to Carry Twins – Some surrogates prefer singleton pregnancies, while others are comfortable carrying twins.

✔ Medical Reduction for Health Reasons – If a twin pregnancy poses serious health risks, the contract defines how decisions will be made with medical guidance.

✔ Elective Reduction for Personal Preference – If intended parents prefer a singleton pregnancy, the surrogate must explicitly agree to this possibility before pregnancy.

✔ Surrogate’s Autonomy – A surrogate cannot be required to undergo a reduction unless she has agreed to it contractually.

💡 At GSHC Surrogacy, all discussions about twins and reduction take place before matching, ensuring mutual understanding and preventing conflicts later.

5. When Is Selective Reduction Considered?

While the majority of twin pregnancies at GSHC Surrogacy are carried to term with great success, in rare cases, a doctor may recommend selective reduction to protect the health of the surrogate or babies.

Medical Reasons for Selective Reduction:

✔ Severe Twin-to-Twin Transfusion Syndrome (TTTS) (Moise, 2018).

✔ Twin Reversed Arterial Perfusion (TRAP) Sequence (Lewi et al., 2010).

✔ Monoamniotic Twins (Mo-Mo) with High Risk of Umbilical Cord Entanglement (Reddy et al., 2005).

✔ Selective Intrauterine Growth Restriction (sIUGR) – When one twin stops developing properly (Evans et al., 2004).

💡 It is important to note that most GSHC twin pregnancies do not require reduction, and our surrogates successfully carry twins to term with excellent medical support.

6. Final Thoughts from GSHC Surrogacy

✔ The majority of GSHC families who experience embryo splitting joyfully welcome healthy twin babies.

✔ Most surrogates are willing and excited to carry twins if medically safe.

✔ Selective reduction is only considered in rare, medically necessary cases and is always handled with care and professionalism.

✔ With proper care, most twin pregnancies result in successful, happy outcomes.

At GSHC Surrogacy, we take pride in helping intended parents and surrogates navigate this journey with clarity, confidence, and support. With expert guidance and compassionate care, most of our families celebrate the arrival of healthy twins with joy and excitement.

💙 Every surrogacy journey is unique, and we are here to guide you every step of the way.

Citations & References

American College of Obstetricians and Gynecologists (ACOG). (2021). Multifetal Pregnancy: Twin, Triplet, and Higher-Order Multifetal Pregnancies.
Blickstein, I., & Keith, L. G. (2003). The Decreasing Incidence of Monozygotic Twinning. Journal of Assisted Reproduction and Genetics, 20(4), 99–102.
Evans, M. I., et al. (2004). Selective Reduction in Multifetal Pregnancies. New England Journal of Medicine, 351(8), 870–875.

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