How Can IVF Siblings Be Conceived Together but Born Years Apart?
Learn how embryos from one IVF cycle can lead to siblings born years apart, and what frozen embryo transfer means for future family-building.
Same Starting Point, Different Birthdays
Two siblings can share the same IVF starting point and still celebrate birthdays years apart. It sounds like a puzzle, but the explanation is one of the practical possibilities created by embryo cryopreservation and frozen embryo transfer (FET).
In everyday language, a family may say that the children were “conceived at the same time.” More precisely, the eggs were fertilized and the embryos began developing during the same IVF cycle. One embryo was transferred earlier, while another was frozen and stored for a later transfer. Their embryonic development began together, but their pregnancies began at different times.
The Story Behind the Question
In a viral social media post, mother Taylor Greenhagen explained that her son and daughter came from the same IVF cycle in 2022. According to Upworthy’s July 2026 account of the siblings conceived together and born years apart, the embryos developed side by side in the laboratory for five days. One transfer led to the birth of her son in 2023; another embryo remained frozen until a later transfer led to her daughter’s birth in 2025.
The children are siblings, not twins in the usual medical sense. Still, their story offers a memorable way to understand how embryos created during one retrieval and fertilization cycle can support more than one future pregnancy.
How One IVF Cycle Can Lead to Births Years Apart
An IVF cycle generally includes ovarian stimulation, egg retrieval, fertilization in a laboratory, embryo culture, and embryo transfer. Sometimes several embryos develop, although the number and quality of embryos vary widely from one cycle to another.
When there is more than one embryo available, a patient and care team may decide to transfer one and cryopreserve others for possible future use. The American Society for Reproductive Medicine’s patient guide to assisted reproductive technology explains that extra embryos may be frozen for future transfer and that using them later can avoid another round of ovarian stimulation and egg retrieval.
The basic sequence looks like this:
- Eggs are retrieved during an IVF cycle.
- Eggs are fertilized, and resulting embryos are observed as they develop.
- One embryo may be selected for transfer.
- Other suitable embryos may be frozen and stored with the patient’s consent.
- Months or years later, an embryo may be thawed and transferred during an FET cycle.
This is how siblings can be connected to the same egg retrieval and fertilization date while having different pregnancy and birth dates.
What Happens While an Embryo Is Frozen?
Embryos are commonly preserved using vitrification, a rapid-freezing method designed to limit ice-crystal formation. Once cryopreserved and maintained under controlled storage conditions, an embryo’s development is paused until it is warmed for a possible transfer.
That pause is why the age difference between siblings does not represent years of embryo growth. In the Greenhagen family’s case, the second embryo did not continue developing throughout the interval between births. Development resumed only after the embryo was warmed and prepared for transfer.
Embryos can remain stored for extended periods, but storage time is only one part of the picture. Future treatment decisions may also depend on embryo quality, laboratory practices, the health of the person carrying the pregnancy, consent agreements, storage policies, and applicable laws. Our guide to how long frozen embryos can remain viable explores those considerations in more detail.
What Is a Frozen Embryo Transfer?
A frozen embryo transfer is a treatment cycle in which a previously cryopreserved embryo is warmed and placed into the uterus. Before transfer, the care team evaluates the uterine lining and determines how to prepare the cycle. Depending on the patient’s circumstances, that preparation may follow a natural ovulatory cycle or involve prescribed hormones.
Because the embryo already exists, an FET does not require repeating the egg retrieval that created it. It is still a medical treatment, however, and it may involve monitoring, medication, laboratory work, and an individualized transfer plan. Not every embryo survives warming, not every transfer results in implantation, and no stored embryo can guarantee a future pregnancy or live birth.
Patients preparing for this step may find it helpful to review what frozen embryo transfer involves and how to prepare before discussing their own protocol with a fertility specialist.
How Embryo Freezing Can Support Family-Building Plans
When a cycle produces embryos that are appropriate for cryopreservation, storing embryos may give a family the option to consider another transfer later without beginning again at egg retrieval. For some people, that creates time between pregnancies. For others, frozen embryos provide another opportunity after an unsuccessful transfer or support plans shaped by health, finances, work, caregiving, or personal readiness.
There is also an important biological detail: the age of the eggs is tied to when they were retrieved, not when a frozen embryo is later transferred. That does not remove every age-related pregnancy consideration, and it does not determine the outcome of a transfer. It is simply one reason embryos from an earlier cycle may remain meaningful to future family-building plans.
These choices can carry emotional, practical, financial, legal, and ethical weight. Before freezing embryos, patients should understand storage fees, consent terms, clinic policies, what will happen if circumstances change, and the available options for embryos they may not use. Clear conversations early in treatment can make later decisions feel less uncertain.
Every Embryo Story Is Different
The idea of siblings beginning as embryos in the same laboratory and meeting years later is remarkable, but it should not create pressure or unrealistic expectations. Some IVF cycles do not produce extra embryos to freeze. Some patients need more than one retrieval, and some frozen embryo transfers do not lead to pregnancy. A joyful family story can offer hope while still leaving room for the many ways treatment may unfold.
At Her Serenity, we know that every embryo can carry deeply personal hope and that no two family-building journeys look exactly alike. Whether you are beginning to explore IVF, considering embryo freezing, or preparing for a future transfer, you deserve clear information, personalized care, and support that respects both your goals and your experience.
Modern fertility treatment can create timelines that once seemed impossible. The most important part is not whether a family’s path resembles anyone else’s. It is having trustworthy guidance and the space to make informed decisions about what comes next.