Comparing prediction of ongoing pregnancy and live birth outcomes in patients with advanced and younger maternal age patients using KIDScore™ day 5: a large-cohort retrospective study with single vitrified-warmed blastocyst transfer

BACKGROUND: The KIDScore™ Day 5 (KS-D5) model, version 3, is a general morphokinetic prediction model (Vitrolife, Sweden) for fetal heartbeat prediction after embryo transfer that was developed based on a large data set that included implantation results from a range of clinics with different patient populations, culture conditions and clinical practices. However, there was no study to comparing their pregnancy and live birth prediction ability among different maternal age. The aim of this study is to analyze the performance of KS-D5 in predicting pregnancy and live birth in various maternal age groups after single vitrified-warmed blastocyst transfer (SVBT). METHODS: A total of 2486 single vitrified-warmed blastocyst transfer (SVBT) cycles were analyzed retrospectively. Confirmed fetal heartbeat positive (FHB+) and live birth (LB+) rates were stratified by Society for Assisted Reproductive Technology (SART) maternal age criteria (< 35, 35–37, 38–40, 41–42 and ≥ 43 years of age). Within each age group, the performance of the prediction model was calculated using the AUC, and the results were compared across the age groups. RESULTS: In all age groups, the FHB+ rates decreased as the KIDScore decreased (P < 0.05). Conversely, the AUCs increased as the maternal age increased. The AUC of the < 35 age group (0.589) was significantly lower than the AUCs of the 41–42 age group (0.673) and the ≥43 age group (0.737), respectively (P < 0.05). In all age groups, the LB+ rates decreased as the KIDScore decreased (P < 0.05). Conversely, the AUCs increased as the maternal age increased. The AUC of the ≥43 age group (0.768) was significantly higher than the AUCs of other age groups (P < 0.05; < 35 age group = 0.596, 35–37 age group = 0.640, 38–40 age group = 0.646, 41–42 age group = 0.679). CONCLUSIONS: In the present study, we determined that the KIDScore model worked well for prediction of pregnancy and live birth outcomes in advanced age patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12958-021-00767-4.