After inducing a withdrawal bleed, letrozole is started on day three to seven of the cycle to ripen the follicle.

“So then um and by the way, do you have a preference for MPA versus micronized? No, not really. Okay. Is because it's such a short course. So So you give the full dose of endometrial progesterone for 5 days. Y the second you take it off, it's the withdrawal of progesterone that causes the lining to shed, right? And then we call that day one. And then you said on day five, we go ahead and start ripening the follicule, right? Ripening the follicle with the aromatase inhibitor. Three to seven. Yeah. Five days. Yeah. Okay. Wow. Yeah. Very cool. Yeah.”