This is one of the first questions I ask women who have been trying for several months without success. And the answer, more often than you might expect, is yes.

Mistimed intercourse is one of the most common and correctable reasons that conception is delayed. It is not because women are not trying. It is because the fertile window is narrower and earlier than most people assume.

The Biology of the Fertile Window

After ovulation, the egg survives for only 12 to 24 hours. Sperm, however, can survive inside the reproductive tract for up to five days in the presence of fertile cervical mucus. This means your fertile window is not the day of ovulation. It is the five to six days leading up to it.

The most effective approach is intercourse every one to two days throughout that window, beginning a few days before the expected LH surge. Many couples time sex on or after the positive OPK result and consistently miss the optimal window.

Where Standard Tracking Falls Short

Most over-the-counter OPK kits measure only the LH surge. LH can rise and fall in the follicular phase without triggering ovulation, creating false positives that mislead your timing. Testing at the wrong time of day amplifies this problem.

My recommendation is to use a kit that measures both LH and progesterone. Progesterone only rises after ovulation has actually occurred. That confirmation is the piece most tracking methods are missing. As of 2026, Mira and Oova are the tools I recommend to my clients for this purpose.

What Else to Track

Cervical mucus is one of the most reliable real-time signs of approaching ovulation. As ovulation nears, it transitions from dry or sticky to stretchy and clear, resembling raw egg white. Learning to recognize this sign gives you a daily read on your cycle that no app can replicate.

Combining OPK testing, cervical mucus observation, and basal body temperature charting gives you the most complete and accurate picture of your cycle. Each method tells you something different, and together they are powerful.

Start from cycle day eight if your cycle is under 30 days. Test at the same time daily. Do not wait for the surge before beginning intercourse. Sperm should already be present when the egg arrives.

Ready to Go Deeper? 

If you are ready to better understand your cycle and optimize your chances of conception naturally, my bestselling book Yes, You Can Get Pregnant walks you through the exact steps I use to support fertility, hormone balance, and egg quality.

And if you want personalized guidance and support, my team and I offer one-on-one fertility coaching for women at every stage of their fertility journey.

Free Fertility Support Resource

I also created a free guide Living In Harmony to help you better understand your body, support hormone balance, and work with your cycle instead of against it while trying to conceive.