Cleavage-stage Versus Blastocyst-stage Embryo Transfer in IVF Patients With Few Embryos

Background and Significance:

It is a major unanswered question for many IVF patients and their providers whether embryos which did not develop into a blastocyst after in vitro culture to day 5-7 of development may have resulted in a pregnancy when transferred into the uterus on day 3, at the cleavage (8-cell) stage. For patients with few (<=5) embryos there is a lack of studies analyzing pregnancy outcomes with either type of embryo transfer (ET). As a result of this uncertainty, these patients and their providers face the difficult clinical decision when to transfer their embryos. This decision is often based on 'expert opinion' and driven by patient anxiety about embryo survival in vitro but not high-quality evidence. Thus, patients with few embryos often receive cleavage-stage transfers forgoing the advantages of blastocyst transfer such as the possibility to transfer a single embryo (SET) which reduces the incidence of multiple pregnancies without reducing the live birth rate per ET.

The investigators are working with nine IVF centers across the US to enroll 1126 patients age 18-44 who are treated for infertility with IVF for the first time and have 5 or fewer embryos. The investigators will assign an equal number of patients by chance to either the 8-cell embryo or the blastocyst transfer group. If there are any surplus embryos that meet freezing criteria they will be frozen and then thawed and transferred in a subsequent cycle. The investigators will monitor patients for 6 months or until all embryos are transferred and, if pregnancy is achieved, until delivery (9 months). For each group the investigators will measure the chance to have a live birth per cycle (primary outcome) and the risk of miscarriage, multiple pregnancy, cycle cancellation (secondary) outcomes based on clinical assessments.

The investigators are working with patients, advocacy groups (RESOLVE, Fertility within Reach), professional societies in reproductive medicine (ASRM, NEFS), clinicians, embryologists, nurses, implementation experts, and a health psychologist, as well as payer (Optum, Winfertility) and policymaker (ASRM, NEFS) representatives to design, and conduct this study and implement the results.

Study Aims:

The goal of the proposed research is to compare the cumulative life birth rate per egg retrieval and the risk of adverse pregnancy outcomes for cleavage-stage versus blastocyst ET in patients with few (<=5) embryos. The investigators hypothesize that blastocyst is superior to cleavage-stage ET in patients with ≤5 zygotes with regard to the primary outcome of cumulative live birth per oocyte retrieval and that there may be differences in other patient-relevant pregnancy outcomes between these two types of ET. Our long-term objective is to develop and implement evidence-based practice guidelines and patient counseling tools for the timing of ET in poor prognosis IVF patients.

Study Description:

This multicenter, randomized, controlled, parallel two-group 1:1 trial compares cleavage-stage vs. blastocyst ET in patients undergoing IVF treatment for infertility within a network of 9 academic IVF centers in the US. The study population consists of first autologous cycle IVF patients ages 18- 44 years with ≤5 zygotes on day 1 of embryo development. The investigators will enroll 563 participants per treatment arm, for a total sample size of 1126. The demographics of the study population at BIVF/BIDMC and other enrolling sites across the US represents that of women seeking care for infertility and reproductive disorders with a mean age of 36.3 years and a mean BMI of 27.4. The investigators expect 69% to be Caucasian, 5% African American, 10% Hispanic, 15% Asian, and 1% Pacific.

The investigators selected outcomes on the basis of importance to patients, providers and other stakeholders:

Primary: cumulative live birth rate per retrieval ('take home baby rate') Secondary: multiple live birth, miscarriage, cycle cancellation Exploratory: time to pregnancy, number of involved procedures, ectopic pregnancy, live birth rate/fresh ET, adverse perinatal outcomes (stillbirth, preterm birth), financial burden, patient satisfaction/psychological distress, facilitators and barriers for patient involvement in the timing of ETs and for implementation and adoption of uniform blastocyst transfer Pre-specified subgroup Analyses: Subgroups of interest are participants with age < 38y and ≥ 38y, <=2 versus 3-5 zygotes, from different ethnic subgroups and poor versus good quality cleavage-stage embryos undergoing single embryo transfer.

Patients will be followed for 6 months after the egg retrieval or until all embryos generated in the cycle have been transferred. All pregnancy outcomes will be assessed from the time of a positive pregnancy test to delivery (9months).

Analytic Methods:

The planned sample size of 1126 participants, equally distributed across the two intervention arms, will provide an estimated power of 99.4%, 91.2% and 80% for a 13.7%, 10% and 8.4% difference in CLBR, respectively. The investigators based our sample size calculation on a 0.05-level two-sided Fisher's exact test for a difference in proportions assuming a 10% cross-over and 10% loss to follow-up rate. Importantly, this sample size will also provide adequate power to determine differences in the secondary outcomes with 80% power.

Stakeholders:

The investigators are working with patients, advocacy groups (RESOLVE, Fertility within Reach), professional societies in reproductive medicine (ASRM, NEFS), clinicians, embryologists, nurses, implementation experts, and a health psychologist, as well as payer (Optum, Winfertility) and policymaker (ASRM, NEFS) representatives to design, and conduct this study and implement the results.