Evaluation of Early Frozen Blastocyst Transfer in A True Natural Cycle Protocol in Comparison to A Hormone Replacement Protocol: A Single-Center Cohort Study.
Bibliographic record
Abstract
OBJECTIVE: Timing of frozen embryo transfer (FET) within a purported window of implantation is of increasing interest, and there is a paucity of evidence surrounding the transfer of frozen embryos early within these frozen embryo transfer protocols. This study aimed to evaluate whether live birth rates were equivalent after FET of blastocysts 4 days after luteinizing hormone (LH) surge in a true natural cycle protocol, compared to a hormone replacement (HR) protocol. MATERIALS AND METHODS: , 2016. Cycles were grouped according to their protocol: true natural cycle (hormonal detection of LH surge with FET scheduled four days later) versus HR cycle (luteal phase gonadotropin-releasing hormone agonist suppression, oral or vaginal estradiol and intramuscular progesterone starting five days before FET). A total of 850 cycles were included, 501 true natural cycles and 349 HR cycles. The primary outcome was the live birth rate, secondary outcomes included clinical pregnancy rate and miscarriage. Logbinomial regression models were performed adjusting for a priori selected variables. RESULTS: Adjusted resulted in live birth rates of 38.7 and 40.4%, [adjusted risk ratio (aRR): 0.96, 95% confidence interval (CI): 0.76-1.22, P=0.729] in the natural cycle and HR groups, respectively. The secondary outcome analyses did not demonstrate any statistically significant difference in the rate of positive human chorionic gonadotropin (hCG), clinical intrauterine pregnancy rate, or miscarriage rate. CONCLUSION: The timing of the FET four days after LH surge in a true natural cycle protocol results in equivalent live birth rates compared to a HR protocol. Results of this study suggest that the window of implantation within the natural cycle may be less finite than currently believed and further prospective studies evaluating the timing of frozen embryo transfer are warranted.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".