When One Embryo Becomes Two: A Real Twin Birth Story and the Science Behind It

They expected one heartbeat. What they got was two.

In July 2019, a hopeful couple matched with a surrogate who would change their lives forever. The medical screening and contract phases moved forward smoothly—everything was going according to plan. On November 19, 2019, a single healthy male embryo was transferred into the surrogate’s uterus. The intended parents looked forward to welcoming one baby boy in the summer of 2020.

But life had a surprise in store.

On December 20, just over four weeks after the transfer, the first ultrasound revealed not one heartbeat—but two. Somehow, the embryo had split in the early stages of development, resulting in identical twins: two baby boys sharing the same genetic blueprint.

The Challenge of Twins: Early Arrival

Identical twin pregnancies, while rare and fascinating, carry significantly higher medical risks than singleton pregnancies. Research has shown that about 60% of twin pregnancies result in preterm birth—defined as delivery before 37 weeks gestation. The earlier the babies are born, the higher the risks of complications such as breathing difficulties, feeding problems, and infections.

On June 10, 2020—at just over 31 weeks gestation—two tiny boys entered the world. Baby A weighed 3 pounds 4 ounces, and Baby B weighed 3 pounds 7 ounces. As expected with preemies, both newborns were immediately admitted to the Neonatal Intensive Care Unit (NICU). But miraculously, despite their small size, they showed no signs of serious medical issues.

After a month of careful monitoring and loving care in the NICU, both boys were discharged—healthy, strong, and ready to go home.

What This Story Teaches Us

1. The Risks of Transferring Two Embryos

Although transferring two embryos may seem like a shortcut to building a bigger family, the risks can be serious. Twin pregnancies are associated with:

• Premature birth (~60% incidence rate)
• Low birth weight (more than 50% of twins weigh under 5.5 lbs)
• Increased risk of gestational diabetes, preeclampsia, and cesarean delivery
• Higher chances of NICU admission and longer hospitalization

👉 Read more about the surrogacy process and what to expect after embryo transfer.

While this story had a fortunate ending, not all twin pregnancies are as smooth. Some result in long-term complications for either the babies or the surrogate.

2. Even One Embryo Can Become Two

In recent years, the majority of intended parents—and fertility clinics—have shifted toward elective single embryo transfer (eSET) to reduce the risk of multiples. CDC data line chart showing the percentage of IVF embryo transfer cycles using single embryo transfer (SET) from 2013 to 2022. Rates rose from about 31% in 2013 to 86% in 2022, reflecting increasing adoption of SET to reduce multiple-fetus pregnancy risks.

But as this story shows, even a single embryo can naturally split.

According to medical literature, the probability of a single embryo splitting into identical twins ranges from 1% to 2%, particularly in assisted reproductive technology (ART) settings.

👉 Learn more about what to expect as a surrogate during your pregnancy timeline.

While rare, it’s a possibility every intended parent should understand.

FAQ

1. Can one embryo split into twins during IVF?

Yes. In rare cases, a single embryo can naturally split into two, resulting in identical twins. This happens in about 1% to 2% of assisted reproduction cases.

2. What are the risks of twin pregnancies after IVF?

Twin pregnancies carry higher risks than singleton pregnancies, including premature birth, low birth weight, gestational diabetes, preeclampsia, and a greater chance of NICU admission.

3. Why do fertility doctors recommend single embryo transfer (SET)?

Doctors recommend SET to reduce the risks of multiple pregnancies. Transferring one embryo at a time increases safety for both the surrogate and the baby while still maintaining high success rates.

4. How common is single embryo transfer in the U.S.?

According to CDC data, the percentage of IVF cycles using single embryo transfer increased from about 31% in 2013 to 86% in 2022, showing it is now the standard approach in fertility clinics.

A Journey Marked by Science, Surprises, and Strength

This family’s journey began with one embryo, grew into a twin pregnancy, and ended with two healthy baby boys—born a little early, but full of life and promise. It’s a story that reminds us—while science can guide the journey, love and life still bring the greatest surprises.

Whether you’re just beginning your surrogacy journey or are ready to take the next step, we’re here to help you every step of the way. 👉 Contact Ivy Surrogacy today.

📚 Sources:

1. Martin JA et al. Births: Final Data for 2022. National Vital Statistics Reports.
2. American College of Obstetricians and Gynecologists (ACOG) – Committee Opinion on Multifetal Pregnancy.
3. Blickstein I, Keith LG. The epidemiology of twin gestations. Best Pract Res Clin Obstet Gynaecol. 2007.