LAUSR

Do maternal AMH and basal FSH profiles impact embryo morphokinetics and does this relationship change with maternal age? Embryo morphokinetics varies with basal FSH and AMH levels and this relationship changes in advanced maternal age (AMA). Basal FSH and AMH levels have been utilised as markers of ovarian reserve/response and IVF/ICSI outcomes. Basal FSH better reflects post-IVF/ICSI live birth occurrence in pre-AMA patients, while AMH appears more robust in AMA patients. Whilst plasma AMH levels reflect oocyte yield, recent data suggest that plasma basal FSH and intrafollicular AMH levels specifically reflect oocyte quality. Oocyte and embryo developmental competence is associated with faster fertilisation and embryonic morphokinetics. The assessment of the relationship between developmental morphokinetics and maternal basal FSH and AMH plasma profiles shall contribute for a better understanding of their roles as fertility markers and regulators. Retrospective cohort study including 1961 first autologous ICSI cycles performed from 2014 to 2020, providing 10774 embryos grouped according to maternal AMH and basal FSH levels in: CF [concordant favourable; AMH>1 (ng/mL), FSH≤10 (IU/L); n = 8055)]; DFA (discordant with favourable AMH; AMH>1, FSH>10; n = 768); DFF (discordant with favourable FSH; AMH≤1, FSH≤10; n = 1362) and CU (concordant unfavourable; AMH≤1, FSH>10; n = 589). Morphokinetic parameters were compared among groups in total, ≤35 (pre-AMA) and >35 (AMA) years old patients, separately. Patients aged 20 to 45 with FSH and AMH levels measured on menstrual cycle day 2 underwent ovarian stimulation, ovum pick-up and ICSI. Embryos were cultured in a time-lapse incubator (Embryoscope). Fertilisation and cleavage morphokinetic parameters [tPNa (time of pronuclei appearance, tPNf (time of pronuclei fading), t2, t3, t4, t5 and t8] were annotated and compared among AMH/FSH groups with the Kruskal-Wallis nonparametric test, followed by a post hoc multiple comparison with Bonferroni correction. In overall embryos, tPNa, tPNf, t2 and t3 varied between AMH/FSH groups. CF were faster than CU embryos for all these parameters [(mean±SEM; hours); tPNa: 6.8±0.02 vs. 7.1±0.08; tPNf: 24.13±0.04 vs. 24.49±0.14; t2: 27.05±0.05 vs. 27.36±0.16; t3: 36.94±0.07 vs. 37.54±0.22 (p < 0.001)]. In addition, CF were faster than DFA (p < 0.001), but not than DFF embryos, for tPNf (CF: 24.13±0.04; DFF: 24.23±0.14; DFA: 24.57±0.14) and t2 (CF: 27.05±0.05; DFF: 27.22±0.12, DFA: 27.42±0.15). In AMA patients, faster morphokinetics was observed when one or both hormonal values were favourable; tPNf, t2 and t3 were reached earlier in CF compared to CU (tPNf: 24.17±0.05 vs. 24.52±0.15; t2: 27.13±0.06 vs. 27.43±0.17; t3: 37.09±0.08 vs. 37.63±0.24; p < 0.05), but not to DFF (tPNf: 24.22±0.12; t2: 27.27±0.14, t3: 36.92±0.19) or DFA embryos (tPNf: 24.39±0.14; t2: 27.34±0.17, t3: 37.26±0.23). Differently, in pre-AMA patients, faster morphokinetics was associated with favourable basal FSH regardless of AMH levels; tPNa and tPNf were reached earlier in CF compared to DFA and CU (p < 0.005), but not to DFF embryos (tPNA: 6.68±0.03, 6.96±0.13, 7.13±0.14, 7.12±0.19; tPNf: 24.05±0.07, 24.27±0.21, 25.14±0.34, 24.37±0.36; for CF, DFF, DFA and CU, respectively). Our study is subjected to the intrinsic limitations of a retrospective analysis and the results could have been affected by variables that were not controlled for. Wider implications of the findings: The findings suggest that lower basal FSH levels are associated with faster early morphokinetics likely reflecting superior oocyte quality in pre-AMA patients. The present data may contribute to improve ART prognostic strategies and provide valuable clues for a better understanding of hormonal regulation of oocyte developmental competence. Not applicable