Similar live birth rates found for blastocyst vs cleavage stage embryo transfers in IVF treatment

Similar live birth rates found for blastocyst vs cleavage stage embryo transfers in IVF treatment | Image Credit: © kieferpix - © kieferpix - stock.adobe.com.

Cumulative live birth rates are similar between blastocyst stage embryo transfers and cleavage stage embryo transfers in women with 4 or more embryos available during in vitro fertilization (IVF) treatment, according to a recent study published in BMJ.¹

Since 1978, there have been over 10 million successful births performed using assisted reproductive technology. Additionally, a public poll indicated increased support for IVF access.²

Respondents of the poll were aged 18 years or older, and 67% agreed IVF coverage should be required by health insurance plans. Of these, 34% expressed strong support while 32% expressed support. Opposition was reported by only 7% of respondents.

IVF or intracytoplasmic sperm injection (ICSI) traditionally included embryo transfer on day 3 following oocyte retrieval, but this has shifted to day 5 or 6 following improvements to in vitro culture conditions.¹

This change was made based on the assumption that only viable embryos may reach the blastocyst stage in vitro, with embryo transfers at the blastocyst stage indicated to improve live birth rates. However, it is unclear whether blastocyst stage embryo transfers and cleavage stage embryo transfers have similar success rates for live births.

To evaluate the rates of live birth from blastocyst vs cleavage stage embryo transfers, investigators conducted a randomized controlled trial. Participants included women aged 18 to 43 years scheduled for their first, second, or third IVF or ICSI oocyte retrieval cycle with at least 4 embryos available.

Women with preimplantation genetic testing, as well as those using frozen-thawed oocytes or donor oocytes were excluded from the analysis. Participants were randomized 1:1 based on age at day 2 after oocyte retrieval.

Ovarian stimulation was controlled using a gonadotrophin releasing hormone agonist or antagonist protocol, and local investigators determined when ICSI use was appropriate. Embryo transfer occurred on day 5 in the blastocyst group vs day 3 in the cleavage group. Women aged 38 years or older could receive double embryo transfers.

The cumulative live birth rates within 12 months of randomization were reported as the primary outcome. Pregnancy rates, pregnancy loss rate, live birth rate after fresh embryo transfer, cancelled transfers, number of embryos needed for live birth, multiple pregnancy rate, and obstetric and perinatal outcomes were reported as secondary outcomes.

There were 603 women assigned to the blastocyst stage group and 599 to the cleavage stage group, of whom 10 and 43, respectively, withdrew after randomization. There were no cases of fresh embryo transfers cancelled because of unsuitable embryo development.

The intention-to-treat cumulative live birth rate was 58.9% in the blastocyst stage group and 58.4% in the cleavage stage group. With a difference of 0.4% and a risk ratio of 1.01, this data indicated no difference in live birth rates between groups.

For secondary outcomes, cumulative pregnancy loss rates were 16.3% in the blastocyst stage group and 24.2% in the cleavage group, with a risk ratio of 0.68. The live birth rates after fresh embryo transfer were 37% and 29.5%, respectively, and the mean numbers of embryo transfers needed for live birth were 1.55 and 1.82, respectively.

These results indicated similar cumulative live births rates from blastocyst stage embryo transfer vs cleavage stage embryo transfer among women with at least 4 embryos. Investigators recommended additional research about the secondary outcomes to address safety concerns.

References

1. Cornelisse S, Fleischer K, van der Westerlaken L, et al. Cumulative live birth rate of a blastocyst versus cleavage stage embryo transfer policy during in vitro fertilisation in women with a good prognosis: multicentre randomised controlled trial. BMJ. 2024;386:e080133. doi:10.1136/bmj-2024-080133
2. Krewson C. Survey shows growing support for IVF coverage in US health care. Contemporary OB/GYN. April 25, 2024. Accessed September 24, 2024. https://www.contemporaryobgyn.net/view/survey-shows-growing-support-for-ivf-coverage-in-us-health-care