What is the fertile window?
Last updated September 3, 2026.
The six days pregnancy can start: the five days before ovulation plus ovulation day, per OWH - because sperm wait up to 5 days while the egg lives about a day. So sex before ovulation beats the day itself, with the peak in the two to three days ending at release. Finding yours: clear, stretchy egg-white mucus just before; predictor kits catch the LH surge 24 to 36 hours ahead; temperature confirms after. The flip warning: the window does not reverse into "safe days" - sperm survival plus irregular cycles defeat the calendar method.
What to do
- Watch the mucus. Clear and stretchy means the window is open now.
- Use predictor kits for precision. The LH surge flags ovulation a day or two out.
- Time sex before ovulation, not on it. The sperm-waiting days carry the odds.
- Never reverse it into safe days. The calendar method fails on sperm math.
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