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The Fertile Window Explained: When You Can Actually Get Pregnant

The fertile window is the 5-6 days each cycle when pregnancy is possible, 5 days before ovulation plus ovulation day. Day 14 is a myth for most people. Here's how to find yours.

The fertile window is narrower than most people think, and its timing is less predictable than period apps suggest. The common advice to "try on Day 14" is based on a population average that is wrong for most individual cycles, sometimes by a week or more. The Biology of the Fertile Window Two biological facts define the fertile window. 1. Egg viability: After ovulation, the egg survives for 12 to 24 hours. If no sperm reaches it in that time, the cycle ends without fertilization. 2. Sperm viability: In fertile cervical mucus (the thin, slippery, egg white consistency produced when estrogen is high), sperm can survive for up to 5 days. Without this mucus, or in the thick, hostile mucus that fills the rest of the cycle, sperm die within hours. Together, these two facts define the fertile window: the 5 days before ovulation (when sperm deposited in fertile mucus can survive to meet the egg when it is released) plus ovulation day itself (the last day the egg is viable). That is 6 days total. Most pregnancies result from sex 1 to 2 days before ovulation, when sperm are already in the fallopian tube waiting. Why "Day 14" Is Wrong for Most People The Day 14 assumption comes from the 1930