Sample size and statistical analysis
SECONDARY
As there is no evidence supporting only 7 days of oestradiol priming in FET-HRT, no formal sample size calculation was performed. Therefore, we arbitrarily decided to include 160 patients.To determine, with 80% power, superiority of one strategy over the other, considering a difference in clinical pregnancy of 10%, with a formal sample size calculation (alfa 0.05 and beta 0.2) we would have required 421 patients in each group, with a total of 842 patients.Continuous variables were presented using mean and standard deviation while categorical characteristics as well as all primary and secondary outcomes were reported using absolute and relative values within their respective groups. Continuous variables were analysed using the Mann–Whitney U test while dichotomous variables were analysed using Fisher’s Exact test. The outcomes were reported with p values and difference of proportion. A All statistical analyses were performed with STATA version 15.1 (StataCorp, College Station, Texas, USA).