From Frozen Cells to Precious Lives: The Growing Impact of Frozen Embryo Births - Dr Duru Shah

Twins born to parents from embryos stored 30 years ago have broken the previous record of baby Molly Gibson, who was born in 2020 from an embryo frozen 27 years ago! For nearly three decades, these embryos were safely preserved in a Fertility Center's IVF facility in liquid nitrogen at -196 degrees Celsius. Do you want to know anything interesting? The first human pregnancy from a frozen embryo was announced in 1983! Millions of kids have been born as a result of frozen embryo transfers since then.

Embryo cryopreservation, or freezing embryos, is an important aspect of ART (Assisted reproductive technology) services. The method entails collecting eggs from the ovaries after stimulating them with hormones, fertilising the eggs with sperm in an IVF facility, producing embryos, and cultivating them to a certain day 3 or day 5 embryo before freezing them. In certain fresh cycles, embryos are placed back inside the uterus during the same cycle that the ovaries are stimulated and the eggs are extracted. During frozen cycles, embryos are frozen and later put back into the same woman's uterus.

With advances in technology and ultra-rapid processes known as vitrification, freezing embryos or gametes has increased IVF cycle success rates. Embryos were frozen utilising the slow freezing approach before vitrification, which resulted in a decreased recovery of viable embryos following thawing. Because the genetic age of the woman at which the eggs or embryos were frozen is the most critical factor affecting the success rate of IVF, the freezing technique allows us to keep the biological age of the embryos.

We freeze embryos for a variety of reasons. They could be for medical or social reasons.

• In PCOS patients: If embryos are transplanted in fresh cycles, women with PCOS who have many embryos may develop a condition known as ovarian hyperstimulation (OHSS). As a result, they are frozen to be moved to a much better environment and to minimise difficulties.

• Endometriosis patients should be offered a pre-treatment for 2-3 months to improve their chances of success. As a result, we produce the embryos, freeze them, treat the women for endometriosis with tablets or injections, and then transfer the embryos.

• Social freezing: When women or couples desire to postpone pregnancy for personal reasons, they might freeze their eggs or embryos.

• Embryo genetic diagnosis/biopsy: Couples with a family history of a genetic problem should have their embryos evaluated before transferring them. Biopsies also allow us to screen for defective embryos before transplanting them.

• Prior to cancer treatment: Chemotherapy and radiotherapy might reduce reproductive potential by decreasing egg quality and quantity. As a result, it is best to freeze your eggs before beginning any cancer therapy.

The good news is that the success rates for fresh and frozen cycles are nearly identical. Few studies support the superiority of frozen cycles over fresh cycles; while frozen transfers promise improved uterine receptivity and provide the patient enough time to recuperate from the fresh cycle, there is no statistical difference between the two cycles. There have been numerous concerns raised about the well-being of children born from frozen cells. 

A recent review study that included kids born between 1987 and 2021 revealed that there is a significant birth weight difference between fresh and frozen-cycle newborns. Babies born from frozen cycles had higher birth weights and are less likely to be born prematurely. 

Surprisingly, there is no difference in birth weight between fresh and frozen cycles of twin pregnancies! Furthermore, there is no evidence that babies born from frozen embryos have a higher risk of birth abnormalities. Concerning neurological consequences, a recent 2020 long-term study investigated the developmental state of babies born from fresh/frozen IVF cycles at >2 years of age. 

They discovered that kids born from both fresh and frozen cycles have equal outcomes in terms of fine motor or problem-solving ability! A recent Nordic study involving nearly 8 million newborns compared children born from fresh cycles or natural conceptions to children born from frozen cycles. They discovered that frozen cycle newborns had a little greater risk of acquiring cancer, although the total risk was extremely low. 

As a result, more evidence-based data is needed to develop worldwide recommendations that take into account the long-term outcomes of children born through frozen cycles.

Many clinics exclusively offer frozen cycles since it makes it easier for the clinic to arrange their IVF cycles, and staff availability, and minimise overlapping cases. Whether this is ethical or not, more studies are needed to justify the use of frozen cycles for all patients requiring IVF.

Disclaimer: The views expressed in this article are of the author and not of Medical Dialogues. The Editorial/Content team of Medical Dialogues has not contributed to the writing/editing/packaging of this article.