Woman Gives Birth to 4 Identical Babies from a Single Egg: How Is It Possible?

On April 2, 2026, in Saint Petersburg, doctors reported an almost impossible phenomenon: identical quadruplets born without fertility treatments. The pregnancy originated from a single fertilized egg that spontaneously split into four genetically identical embryos an exceptionally rare event in medicine.

In the world of fertility, there are stories that surprise even experts. This is one of the most extraordinary cases. Estimated to occur in approximately 1 in 15 million pregnancies, this phenomenon opens the door to a deeper understanding of how human reproduction works and the advancements in treatments such as IVF.

The babies were born at 32 weeks of gestation in good overall condition:
• 1.400 kg – 38 cm
• 1.570 kg – 41 cm
• 1.640 kg – 41 cm
• 1.360 kg – 37 cm

Despite being a high-risk pregnancy, specialists report a favorable progression.

Beyond how extraordinary this case is, it also raises important questions for intended parents and women interested in egg donation.

What does it mean for babies to be identical?

When we talk about identical babies, we are referring to monozygotic twins (or in this case, quadruplets). This occurs when a single fertilized egg splits into multiple embryos.

Under normal conditions, this can result in twins. However, for the same embryo to split into four is extremely rare.

How does this phenomenon occur?

After fertilization, the embryo begins to divide. In this specific case:

• A single egg was fertilized.

• The embryo divided multiple times.

• Each division resulted in a genetically identical embryo.

This process cannot be fully predicted or controlled, even with advanced fertility treatments.

The role of IVF in these cases

IVF (in vitro fertilization) is a key treatment in many fertility journeys. It involves fertilizing an egg with sperm in a laboratory and then transferring the embryo to the uterus.

In rare cases, like this one, the transferred embryo can spontaneously split.

Is it common in IVF?

No. While IVF slightly increases the likelihood of multiple pregnancies, the occurrence of identical quadruplets remains extremely unusual.

However, cases like this highlight the complexity and precision of the fertility process.