The ovulation trigger-OPU time interval of different ovarian protocols in ART: a retrospective study

To explore the trends of oocyte and pregnancy outcomes over the ovulation trigger-OPU (oocyte pickup) time interval in four mainly used COH protocols.

This retrospective study was conducted between January 2013 and July 2018. The IVF/ICSI cycles of the patients with normal ovarian reserve were included. The number of total patients was 4673, which consisted of long agonist protocol (n = 819), short agonist protocol (n = 1703), mild stimulation protocol (n = 1627), and GnRH antagonist protocol (n = 524). The primary outcome was mature oocyte rate.

The ovulation trigger-OPU time interval and COH protocol were related to cycles with > 80% MII oocytes. Four protocols showed apparently different trends of retrieved oocyte rate and mature oocyte rate over the ovulation trigger-OPU time interval, and the long agonist protocol had the most delayed time interval than other three COH protocols in retrieving more than 60% oocytes (35.4-39.6 h vs. 34.6-38.6 h vs. 32.5-37.5 h vs. 33.8-37.7 h) and getting more than 80% mature oocytes (35.0-39.7 h vs. 36.0-37.7 h vs. 34.1-35.5 h vs. 34.5-36.3 h). And the adjusted odds ratio (OR) of the cumulative live birth rate (CLBR) (OR 1.360, 95% Confidence Interval (CI) 1.156-1.549, P < 0.05) significantly increased with the trigger-OPU time interval in the long agonist protocol.

For getting more and mature oocytes, the ovulation trigger-OPU time intervals should be gradually prolonged from the mild stimulation protocol, the GnRH antagonist protocol, and the short protocol to the long agonist protocol. And the prolonged ovulation trigger-OPU time interval in the long agonist protocol brings higher live birth rate (LBR) and CLBR.