M. Aguirre

Clinical rationale for cryopreservation of entire embryo cohorts in lieu of fresh transfer

Recent dramatic increases in success rates with frozen-thawed embryo transfer (FET) are encouraging, as are numerous findings of several reduced risks with FET when compared with fresh transfer. These reduced risks include low birth weight and prematurity, among others. However, FET is also associated with increased risks of macrosomia and large for gestational age. There have been reports of greater implantation and pregnancy rates with FET than with fresh autologous embryo transfer, suggesting superior endometrial receptivity in the absence of ovarian stimulation. As cryo-technology evolves, there is potential for further increase in FET success rates, but for now it may be best to follow an individualized approach, balancing fresh transfer and embryo cohort cryopreservation options while considering patient characteristics, cycle parameters, and clinic success rates.

Comparison of “triggers” using leuprolide acetate alone or in combination with low-dose human chorionic gonadotropin

This retrospective study of fresh autologous blastocyst transfers in high responders compared ongoing pregnancy rates in cycles that followed trigger with GnRH agonist (GnRHa) alone with standard luteal support, GnRHa alone with enhanced luteal support, or GnRHa with concomitant low-dose hCG (dual trigger). Ongoing pregnancy rates were significantly increased with the dual trigger or with enhanced luteal support, whereas the incidence of clinically significant ovarian hyperstimulation syndrome was 0.0% in the groups receiving only GnRHa and 0.5% (1 of 182) in patients receiving GnRHa with concomitant low-dose hCG.

Embryo cryopreservation rescues cycles with premature luteinization

OBJECTIVE To determine whether embryo cryopreservation in cycles with elevated preovulatory P followed by thaw, extended culture, and transfer results in greater ongoing pregnancy rates than fresh blastocyst transfer. DESIGN Retrospective matched cohort study. SETTING Private fertility center. PATIENT(S) The study group consisted of 118 consecutive thaws of bipronucleate (2PN) oocytes derived from autologous cycles with elevated preovulatory P, resulting in 95 blastocyst transfers. The control group was selected by matching on the number of 2PN oocytes and patient age and consisted of 118 fresh cycles with elevated preovulatory P, including 108 fresh autologous blastocyst transfers. All patients were <41 years old at the time of stimulation. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Implantation and ongoing pregnancy rates. RESULT(S) The study group had significantly fewer blastocysts per 2PN oocyte than the control group (19.7% vs. 36.8%, respectively) and a significantly greater cancellation rate (19.5% vs. 8.5%, respectively). However, the ongoing pregnancy rate per cycle was significantly higher in the study group than in the control group (56.8% vs. 32.2%, respectively), resulting from greater rates of implantation (56.8% vs. 26.9%, respectively) and of ongoing pregnancy per transfer (70.5% vs. 35.2%, respectively). CONCLUSION(S) In cycles with elevated preovulatory P, the probabilities of implantation and ongoing pregnancy are increased if all 2PN oocytes are cryopreserved and subsequently thawed and cultured to the blastocyst stage before transfer.

Frozen-thawed embryo transfer is associated with a significantly reduced incidence of ectopic pregnancy.

OBJECTIVE To compare the incidence of ectopic pregnancy (EP) after fresh ET and thawed ET. DESIGN Retrospective cohort study. SETTING Private fertility center. PATIENT(S) This retrospective study included 2,150 blastocyst transfers, including all 1,460 fresh autologous blastocyst transfers and all 690 transfers of autologous blastocysts derived from post-thaw extended culture of thawed bipronuclear oocytes in the 8-year study period 2004-2011. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Visualized EP and treated persistent pregnancy of unknown location. RESULT(S) The rate of visualized EP was 1.5% in pregnancies in fresh autologous cycles, which was significantly more than the rate of 0 with autologous post-thaw extended culture. The rates of treated persistent pregnancy of unknown location were 2.5% and 0.3% in these two groups, respectively, a difference that was also statistically significant (relative risk 7.3, 95% confidence interval 1.7-31.0). CONCLUSION(S) Relative to fresh transfer, thawed ET was associated with significantly reduced incidence of EP. These findings are consistent with ovarian stimulation increasing the risk of EP.

Freeze-all can be a superior therapy to another fresh cycle in patients with prior fresh blastocyst implantation failure

Implantation failure has various causes, including impaired uterine receptivity following ovarian stimulation. This retrospective cohort study compared outcomes in patients with prior implantation failure who elected to undergo another fresh cycle versus those who opted for embryo cohort cryopreservation (freeze-all) and subsequent thaw. There were 269 patients with implantation failure following fresh autologous blastocyst transfer opting to undergo a subsequent cycle, with 163 choosing another fresh cycle and 106 electing freeze-all and subsequent thaw. Multiple logistic regression analysis indicated that cohort cryopreservation was associated with greater chance of live birth when compared with another fresh cycle (P < 0.0001). The odds ratio for live birth with freeze-all relative to a fresh cycle was 3.8 (95% CI 2.1-7.2). A second analysis was then performed using cumulative live birth rate as the outcome measure. Multiple logistic regression indicated freeze-all was associated with greater cumulative live birth rate than was a fresh cycle (OR 1.9, 95% CI 1.1-3.3, P = 0.0287). These findings suggest that, following implantation failure with fresh blastocysts, patients have a significantly greater chance of live birth with freeze-all and subsequent thaw than with another fresh cycle.

High ongoing pregnancy rates after deferred transfer through bipronuclear oocyte cryopreservation and post-thaw extended culture

OBJECTIVE To describe success rates with bipronuclear (2PN) oocyte cryopreservation, followed by thaw, extended culture, and blastocyst transfer. DESIGN Retrospective study. SETTING Private fertility center. PATIENT(S) There were 48 blastocyst transfers after post-thaw extended culture in patients less than 35 years old and 43 transfers in patients 35-40 years old. INTERVENTION(S) Patients opted for cryopreservation of their entire cohorts at the 2PN stage. Thawed 2PN oocytes were cultured to the blastocyst stage before transfer. MAIN OUTCOME MEASURE(S) Implantation, ongoing pregnancy. RESULT(S) Among patients less than 35 years old at oocyte retrieval, there were 59 thaws of 2PN oocytes, 48 blastocyst transfers, and 40 ongoing pregnancies (79.2% per transfer), the implantation rate was 64.2%, and the ongoing pregnancy rate (PR) per thaw was 64.4%. Among patients 35-40 years of age at retrieval, there were 58 thaws, 43 blastocyst transfers, and 22 ongoing pregnancies (51.2% per transfer), the implantation rate was 44.0%, and the ongoing PR per thaw was 39.3%. Patients less than 35 years old had significantly greater rates of implantation and ongoing pregnancy than did patients 35-40 years of age. Patients with 12 or more 2PN oocytes had significantly greater rate of ongoing pregnancy than those with fewer than 12 2PN oocytes. CONCLUSION(S) Post-thaw extended culture and blastocyst transfer yield high rates of implantation and ongoing pregnancy. Ongoing PRs decline with increasing age.

Similar ongoing pregnancy rates after blastocyst transfer in fresh donor cycles and autologous cycles using cryopreserved bipronuclear oocytes suggest similar viability of transferred blastocysts

This retrospective cohort study compared blastocyst transfers in 136 fresh oocyte donor cycles and 69 autologous cycles using blastocysts derived from culture of thawed bipronuclear oocytes, all with oocytes derived from patients or donors less than 35 years old. The autologous cycles and oocyte donor cycles had similar rates of implantation (65.9% vs. 62.1%, respectively) and ongoing pregnancy (79.7% vs. 75.0%, respectively), suggesting that autologous blastocysts transferred after post-thaw extended culture have viability and implantation potential that are comparable with those of blastocysts transferred in fresh oocyte donor cycles.

The risk of embryo-endometrium asynchrony increases with maternal age after ovarian stimulation and IVF

This retrospective cohort analysis examined the effects of maternal age on the incidence of factors associated with embryo-endometrium asynchrony in fresh autologous blastocyst transfer. The study included 1169 routine fresh autologous blastocyst transfers. The main outcome measure was asynchronous transfer defined by delayed (day 6) blastocyst transfer or elevated pre-ovulatory serum progesterone level. Compared with patients younger than 35 years, patients 35 years or older had increased risk of having at least one risk factor for asynchronous transfer, including premature progesterone elevation or delayed blastocyst transfer (RR 1.36; 95% CI 1.24 to 1.50). The older group had increased risk of simultaneously having both risk factors (RR 1.61, 95% CI 1.17 to 2.21) compared with the younger group. In patients younger than 35 years, live birth rate per transfer was 62.9% with day 5 transfer and low progesterone, declining to 27.9% for day 6 transfer combined with elevated progesterone. In patients 35 years or older, live birth rate per transfer was 38.0% with day 5 transfer and low progesterone, declining to 18.1% for day 6 transfer combined with elevated progesterone. Indicators of embryo-endometrium asynchrony increase in prevalence as women age and asynchrony disproportionately decreases birth rates in older patients.