Pregnancy After Ovulation: Likelihood of Conception
If you had sex a few days after ovulation, pregnancy is extremely unlikely to occur, as the fertile window effectively closes within hours after the egg is released. 1
Understanding the Fertile Window
The biological reality of conception is quite narrow and time-sensitive:
Conception can only occur during a 6-day window that ends on the day of ovulation itself. 1 This means intercourse must happen before or on the day of ovulation—not after.
The probability of conception drops to essentially zero after ovulation has occurred. 1, 2 Research tracking 625 menstrual cycles found that all pregnancies resulted from intercourse during the 5 days before ovulation through the day of ovulation, with no pregnancies occurring from intercourse after ovulation. 1
The egg (ovum) survives only approximately 0.7 days (roughly 12-24 hours) after release. 3 Once this brief window passes, fertilization cannot occur regardless of sperm presence.
Why Timing Matters
The biological mechanism explains this narrow window:
Sperm can survive in the female reproductive tract for an average of 1.4 days, with a 5% probability of surviving more than 4.4 days. 3 This is why intercourse before ovulation can result in pregnancy—the sperm are waiting when the egg is released.
After ovulation, the egg rapidly degenerates if not fertilized. 2 Studies using both basal body temperature and urinary hormone assays confirmed that day-specific pregnancy probabilities fall to zero after ovulation. 2
Practical Implications
If you are certain ovulation occurred on a specific date:
Intercourse 1-2 days after confirmed ovulation carries virtually no pregnancy risk. 1, 3
The highest conception probability (33%) occurs with intercourse on the day of ovulation itself, declining to 10% when intercourse occurs 5 days before ovulation. 1
Important Caveats
The major challenge is accurately identifying when ovulation actually occurred. 4 During an average 28-day cycle, ovulation generally occurs during days 9-20, showing substantial variability even in women with regular cycles. 4
If you are relying on calendar methods, apps, or symptoms to identify ovulation, there is significant potential for error in timing. 4 The timing of the fertile window varies greatly even among women with regular cycles. 4
Only methods like urinary LH testing or ultrasound provide reasonably accurate real-time ovulation detection. 5
If pregnancy is not desired and you had unprotected intercourse within the past 5 days, emergency contraception should be considered regardless of presumed cycle timing. 4 Emergency contraceptive pills should be taken as soon as possible within 5 days of unprotected intercourse, and copper IUDs can be inserted up to 5 days after ovulation. 4