I've been TTC for 1.5 years now and know more than I should about fertility, haha. I just started using the <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a> because my old app has started not functioning properly. This morning I got my positive OPK, which means in 24-36 hours I'll be ovulating. Why is it that the app says I have the highest chance of getting pregnant today? It should be tomorrow. Any ideas? As a background, I'm on my second round of <a href="https://glowing.com/glow-fertility-program">IUI</a>, and my doc has me call in when I get a positive OPK, and schedule the <a href="https://glowing.com/glow-fertility-program">IUI</a> for the NEXT day (ie: tomorrow).