The entire range of trigger-day endometrial thickness values in fresh in vitro fertilization cycles is in direct independent correlation with the live birth rate

ABSTRACT Research question What is the association of the entire range of the trigger-day endometrial thickness (EMT) with the live birth rate (LBR) following in vitro fertilization (IVF) and fresh embryo-transfer (ET)? Although EMT is amenable to convenient non-invasive routine measurement, studies of the association between the pre-trigger EMT and ART outcome have yielded equivocal results. Design A cohort of all IVF fresh day 3 ETs in patients age ≤42 in a single center between 2009-2017. LBR was calculated for all trigger-day EMT values, stratified into 5 groups overall and within subgroups of patient age and ovarian response. Univariate analysis and multivariate logistic regression model were used to compare the LBRs at different EMT measurements adjusting for various independent variables. Results 5133 cycles were included. LBRs were as follows: 11.22% (35/312) in cycles with EMT ≤6mm, 17.98% (280/2114) in cycles with EMT 7-9mm, 23.44% (476/2031) in cycles with EMT 10-12mm, 25.62% (144/562) in cycles with EMT 13-15mm, and 34.21% (39/114) in cycles with EMT ≥16 mm (P Conclusions The pre-trigger EMT is in significant independent correlation with the LBR, even after adjusting for age and ovarian response. Maximal endometrial proliferation is beneficial, and fresh ET can be performed at high EMT values without endangering the outcome of the cycle.