Fresh versus Frozen: Embryo transfer for women seeking fertility treatment

This study investigated the live-birth rates following fresh or frozen embryo transfer in women who ovulate.

They found there was no difference in the live birth rates following either frozen- or fresh-embryo transfer.

Embryo transfer is one of the final steps in a fertility treatment cycle. At this point the oocyte (egg) has undergone in vitro fertilization (IVF, a procedure in which the egg is fertilized by sperm outside of the body) and is ready for implantation in the women’s uterus.

In some cases, patients may choose to freeze the fertilized embryo for implantation at a later stage. There is evidence to suggest that frozen embryo transfer may result in higher live-birth rates than fresh-embryo transfer. Anovulation is a condition where no oocytes are released. Frozen-embryo transfer may be more effective in these women, however, it is not clear whether the same effects are seen in women that are ovulating. 

This study investigated if frozen-embryo transfer had a higher live-birth rate than fresh-embryo transfer In ovulatory women.

This study included 2157 women undergoing fertility treatment for the first time. Patients were randomly assigned to undergo either frozen-embryo transfer or fresh-embryo transfer. Depending on the group they were assigned, women also began a standard medication regime to support implanation. Women that successfully became pregnant continued for the rest of this trial until they gave birth.

There was no difference in the live-birth rate between women that underwent either frozen- or fresh-embryo transfer. There was also no difference in the success rates of implantation or clinical pregnancy (becoming pregnant). Frozen-embryo transfer was associated with 68% reduced risk of ovarian hyperstimulation (painful, swollen ovaries that can lead to a serious increase in fluid in the abdomen or chest).

This study concluded that there was no difference in the live birth rates following either frozen- or fresh-embryo transfer.

There was a high dropout rate in this trial.  Embryos were transferred at particular developmental stage however, this protocol is not used by all clinicians. Transferring the embryos at a different stage may yield different results. 

If you have any concerns regarding embryo transfer and fertility treatment in general, please discuss with your health care professional.