Does ICSI timing impact cumulative live birth and perinatal outcomes - a cohort study

The objective was to investigate whether there are differences in cumulative live birth rate, cumulative clinical pregnancy rate, or perinatal outcomes after delaying ICSI timing. The design was a retrospective cohort study at Fertility North in Australia using 1,969 ICSI cycles with different ICSI timings among 1,078 patients from 2017 to 2022. Cumulative outcomes included cumulative live birth and cumulative clinical pregnancy rates per oocyte retrieval cycle. Perinatal outcomes included preterm birth, low/high birthweight, and small/large for gestational age. Binomial logistic regression and multinomial logistic regression were used. Generalised estimating equation (GEE) was incorporated into the logistic regression analyses to account for the cluster effect from patients undergoing multiple retrieval cycles. ICSI timing was grouped into quartiles: Q1(37.1-41.1h, n = 498), Q2(41.2-42.4h, n = 510), Q3(42.5-43.3h, n = 483), and Q4(43.4-46.8h, n = 478). No significant difference was found in cumulative live birth in Q2 (aOR: 0.79, 95%CI: 0.55-1.14), Q3 (0.87, 0.61-1.25), and Q4 (0.86, 0.58-1.27), compared with Q1, respectively. Similarly, there was no significant difference in cumulative clinical pregnancy rate between the four groups. Furthermore, no significant differences were found in preterm birth, low birth weight, high birth weight, small for gestational age, and large for gestational age in Q4, compared to Q1. Delaying ICSI until 46.8 hours post-trigger does not compromise cumulative clinical pregnancy or live birth rates, or increase adverse perinatal risks.