Freeze-only versus fresh embryo transfer in a multicenter matched cohort study: contribution of progesterone and maternal age to success rates.

OBJECTIVE: To compare implantation and ongoing pregnancy rates in freeze-only versus fresh transfer cycles. DESIGN: Retrospective matched cohort study. SETTING: Not applicable. PATIENT(S): Women selected using a matching algorithm for similar distributions of clinical characteristics for a total of 2,910 cycles (1,455 fresh cohort and 1,455 freeze-only cohort). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Implantation and ongoing pregnancy rates. RESULT(S): Implantation and ongoing pregnancy rates were statistically significantly higher in the freeze-only transfer cohort than in the matched fresh transfer cohort: ongoing pregnancy rate for freeze-only was 52.0% (95% confidence interval [CI], 49.4-54.6) and for fresh was 45.3% (95% CI, 42.7-47.9), odds ratio (OR) 1.31 (95% CI, 1.13-1.51). In a stratified analysis, the odds of ongoing pregnancy after freeze-only transfer were statistically significantly higher for women both above and below age 35 with progesterone concentration >1.0 ng/mL (age ≤35: OR 1.38 [1.11-1.71]; age >35: OR 1.73 [1.34-2.24]). For women with progesterone concentration ≤1.0 ng/mL, no statistically significant difference in freeze-only odds of ongoing pregnancy was observed in either age group. The sensitivity analysis revealed that increasing maternal age alone (regardless of progesterone) trended toward a more beneficial effect of freeze-only cycles. A lower progesterone concentration was associated with statistically significantly higher ongoing pregnancy odds for fresh but not freeze-only cycles. CONCLUSION(S): Freeze-only transfer protocols are associated with statistically significantly higher ongoing implantation and pregnancy rates compared with fresh transfer cycles. This effect is most pronounced for cycles with progesterone >1.0 ng/mL at trigger and may also be stronger for older patients.

Clinically recognizable error rate after the transfer of comprehensive chromosomal screened euploid embryos is low.

OBJECTIVE: To determine the clinically recognizable error rate with the use of quantitative polymerase chain reaction (qPCR)-based comprehensive chromosomal screening (CCS). DESIGN: Retrospective study. SETTING: Multiple fertility centers. PATIENT(S): All patients receiving euploid designated embryos. INTERVENTION(S): Trophectoderm biopsy for CCS. MAIN OUTCOME MEASURE(S): Evaluation of the pregnancy outcomes following the transfer of qPCR-designated euploid embryos. Calculation of the clinically recognizable error rate. RESULT(S): A total of 3,168 transfers led to 2,354 pregnancies (74.3%). Of 4,794 CCS euploid embryos transferred, 2,976 gestational sacs developed, reflecting a clinical implantation rate of 62.1%. In the cases where a miscarriage occurred and products of conception were available for analysis, ten were ultimately found to be aneuploid. Seven were identified in the products of conception following clinical losses and three in ongoing pregnancies. The clinically recognizable error rate per embryo designated as euploid was 0.21% (95% confidence interval [CI] 0.10-0.37). The clinically recognizable error rate per transfer was 0.32% (95% CI 0.16-0.56). The clinically recognizable error rate per ongoing pregnancy was 0.13% (95% CI 0.03-0.37). Three products of conception from aneuploid losses were available to the molecular laboratory for detailed examination, and all of them demonstrated fetal mosaicism. CONCLUSION(S): The clinically recognizable error rate with qPCR-based CCS is real but quite low. Although evaluated in only a limited number of specimens, mosaicism appears to play a prominent role in misdiagnoses. Mosaic errors present a genuine limit to the effectiveness of aneuploidy screening, because they are not attributable to technical issues in the embryology or analytic laboratories.