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.