Statistical Analysis
Categorical and continuous variables are presented in the text and tables as percentages or means with standard deviations or 95% confidence intervals (95% CI). To compare means, ANOVA tests were used with Bonferroni post-hoc tests. For multivariate analyses to control possible bias and to calculate adjusted ORs, logistic regression analysis was performed considering the proportion of ET that used donated oocytes, the day of ET, the mean number of embryos transferred per procedure, age, and the mean of the prior number of embryos transferred per patient as clinically relevant variables. Because this study was conducted over a five year period and couples may have had consecutive ET with different diagnostic techniques (e.g., ERA and then ERA + PGT-A), meaning the groups lack independence and there is potential correlation between data from each group, generalized estimating equations were utilized to estimate the parameters of a generalized linear model with a possible unknown correlation between outcomes. Statistical significance was established at P< 0.05. Calculations were made with R version 3.5.0 (R core team)36. Estimation of statistical power was conducted to define the probability that a given test rejects a false null hypothesis to better interpret results, give context, and focus the discussion.