Two large studies concluded that embryos fresh or frozen options have the same results but different bioethical implications.

Since the advent of in vitro fertilization (IVF)  in 1978, fresh embryos have generally been used in the procedure. However, their use has the immediacy with which the clinic must act. As a result, in the last decade, the use of frozen human embryos (read HERE) has been implemented. In view of this, the question that arises is whether the pregnancy and live birth rates using frozen embryos improve or reduces that of fresh embryos and their destruction.

Have embryos fresh or frozen options a bioethical implication?

The results of several trials, generally with a small number of patients, have suggested that the pregnancy and live birth rates obtained with fresh embryos can be improved using frozen embryos.

The first study two years ago

On 11 January, an article was published in the New England Journal of Medicine that assessed this read HERE. The study included 782 infertile women without polycystic ovaries, who underwent one or two IVF cycles with both fresh and frozen embryos. The fresh embryos were 3 days old, while the frozen embryos were thawed on the day of the transfer. When fresh embryos were used, two were transferred in the stimulated cycle.


Using frozen embryos reduces that of fresh embryos that involve their process


After having completed the corresponding cycles, 142 pregnancies were achieved in 391 women (36.3%) in the frozen embryo group and in 135 of 391 women (34.5%) in the fresh embryo group. Similarly, the live birth rate after the first embryo transfer was 33.8 % in the frozen embryo group and 31.5% in the fresh embryo group. The authors, therefore, believe that “the transfer of frozen embryos did not result in significantly higher rates of ongoing pregnancy or live birth than the transfer of fresh embryos”.

A recent study confirms  that embryos fresh or frozen options have the same results

A recent study published in the British Medical Journal, August 5, 2020 (read HERE) arrives at the same conclusion using a different methodology. The authors evaluated 460 women between the ages of 18 and 39 with regular menstrual cycles. Pregnancy rates were very similar in both groups: 27.8% for the frozen embryo transfer group and 29.6% for the fresh transfer group. There were no differences in live birth rates either: 27.4% in the frozen transfer group and 28.7% in the fresh transfer group. Furthermore, complications did not differ between the groups. The authors, therefore, concluded that in women with regular menstrual cycles, both fresh and frozen embryos can be used as the pregnancy and live birth rates obtained are very similar.

In this regard, could opts to frozen embryos for IVF resolve a relevant bioethical problem: dramatically increase of Frozen embryos abandoned. “An average of seven cryopreserved embryos remain after in vitro fertilization has taken place and these can be cryopreserved and available to the family for five years”.  “Nevertheless, one-third of the families decide to keep them in storage indefinitely”, while others donate them to biotechnology research, which of course involves their destruction” (read more HERE).

See our IVF bioethical assessment