If a woman exhibits consistent "fallback rise" BBT chart w/2dpo temp dip, will IUI on 1dpo reduce chance of fertilization b/c hormone change day after?

Sorry, it's kinda confusing what you are asking: "fallback rise" does not mean anything medically specific to me.

Bbt is a sketchy way to time IUI under best of circumstances; i can say that 1 day after a certain ovulation (which BBT is not) would likely be late for conception. Iui strategy favors inseminating a little early rather than a little late. Would you like to video or text chat with me?