Best Time to Have Sex to Get Pregnant
Understanding when to have sex is one of the most important factors in getting pregnant quickly. While conception might seem straightforward, the biological reality is that you can only get pregnant during a very narrow window each cycle—and timing within that window makes a significant difference in your chances.
The science is clear: pregnancy doesn't happen from sex on ovulation day as often as many people think. The highest conception rates come from sex in the days leading up to ovulation, when sperm are already in the reproductive tract waiting for the egg.
Understanding Your Fertile Window
Your fertile window spans approximately six days: the five days before ovulation plus ovulation day itself. This window exists because of the different lifespans of sperm and eggs. Sperm can survive in the female reproductive tract for up to five days under optimal conditions, while an egg survives only 12-24 hours after release.
This timing mismatch actually works in your favor—it means you don't need to time sex perfectly to the hour of ovulation. Instead, having sperm already present and waiting gives you the best odds of the sperm meeting the egg before it degrades.
Day-by-Day Conception Probability
Research has mapped out conception rates for each day of the fertile window. The data consistently shows that sex in the two days before ovulation yields the highest pregnancy rates.
| Timing | Conception Chance | Notes |
|---|---|---|
| 5 days before ovulation (O-5) | ~4% | Edge of fertile window; sperm may not survive |
| 4 days before ovulation (O-4) | ~8% | Low but possible; fertile window begins |
| 3 days before ovulation (O-3) | ~14% | Good timing; sperm has time to reach tubes |
| 2 days before ovulation (O-2) | ~25% | Excellent timing; ideal for sperm positioning |
| 1 day before ovulation (O-1) | ~25-30% | Peak fertility day; optimal timing |
| Ovulation day (O) | ~15% | Still fertile but egg may release before sperm arrive |
| Day after ovulation (O+1) | ~0-5% | Very unlikely; egg typically already degraded |
Why Day Before Ovulation Beats Ovulation Day
It seems counterintuitive, but having sex the day before ovulation typically leads to higher pregnancy rates than sex on ovulation day. The biology explains why this happens.
After ejaculation, sperm need time to travel through the cervix and uterus to reach the fallopian tubes—a journey that takes several hours. They also undergo a process called capacitation, which prepares them to fertilize an egg. This process takes 6-12 hours. If you have sex on ovulation day, the egg may be released and begin degrading before sperm complete their journey and preparation.
When sperm are already waiting in the fallopian tubes before the egg releases, they can fertilize it almost immediately. This is why the 24-48 hours before ovulation consistently show the highest conception rates.
How Often Should You Have Sex?
One of the most common questions couples have is about frequency. Should you have sex every day? Every other day? Save up for peak days? Research provides clear guidance here.
Does Daily Sex Hurt Your Chances?
A common myth suggests that men should abstain for several days to "save up" sperm before the fertile window. Research has largely debunked this approach. Daily ejaculation does lower sperm concentration per ejaculate, but it also ensures fresher, more motile sperm and doesn't significantly reduce conception rates.
For men with normal sperm counts, daily sex during the fertile window is perfectly fine. For men with lower sperm counts, every other day may be slightly better to allow counts to replenish—but the difference is modest. The most important thing is ensuring you hit the 2-3 days before ovulation.
While abstaining does increase sperm count per ejaculate, it also increases the percentage of older, less motile sperm. Extended abstinence (more than 5-7 days) can actually decrease sperm quality due to DNA fragmentation in older sperm.
How to Know When You're Ovulating
To time sex effectively, you need to predict or detect ovulation. Several methods exist, ranging from simple calendar tracking to advanced fertility monitors. Most experts recommend combining multiple methods for the most accurate prediction.
Ovulation Predictor Kits (OPKs)
OPKs detect the luteinizing hormone (LH) surge that occurs 24-36 hours before ovulation. When you get a positive test, ovulation is imminent—making that day and the next your peak fertility days. Start testing a few days before you expect to ovulate based on your cycle length.
Cervical Mucus Tracking
As ovulation approaches, cervical mucus becomes clearer, more slippery, and stretchy—often described as having an "egg white" consistency. This fertile-quality mucus helps sperm survive and swim efficiently. When you notice this change, you're likely in your fertile window.
Basal Body Temperature (BBT)
Your temperature rises slightly (0.2-0.5°F) after ovulation due to progesterone. While BBT tracking can confirm that ovulation occurred, it can't predict it in advance—by the time you see the temperature rise, ovulation has already happened. BBT is most useful for learning your cycle patterns over several months.
Positions, Timing, and Other Factors
Beyond knowing when to have sex, couples often wonder if other factors affect their chances. Here's what the research actually shows.
Does Position Matter?
There's no scientific evidence that any particular sexual position increases conception rates. Sperm reach the cervix within seconds of ejaculation regardless of position, and are swimming toward the fallopian tubes within minutes. The position that works best is the one that's comfortable and enjoyable for both partners.
Should You Stay Lying Down After Sex?
Many women lie down for 10-15 minutes after sex, and while this is unlikely to hurt, research hasn't shown it significantly improves conception rates. One study of IUI (intrauterine insemination) patients found a small benefit to lying down for 15 minutes, but results were not replicated in natural conception studies. If it makes you feel better, go ahead—but don't stress if you need to get up.
Does Lubricant Affect Fertility?
This one matters. Most commercial lubricants (including popular brands like KY Jelly, Astroglide, and even saliva) can impair sperm motility. If you need lubrication, use fertility-friendly products specifically designed to match the pH and consistency of fertile cervical mucus.
Optimal Timing Strategy by Cycle Day
Putting it all together, here's a practical approach for a 28-day cycle. Adjust timing based on your actual cycle length—if your cycle is shorter or longer, shift these days accordingly.
- Days 8-10: Begin ovulation testing; consider starting regular sex
- Days 10-11: Have sex (sperm coverage begins)
- Days 12-13: Have sex daily or every other day; OPKs may turn positive
- Day 14: Continue sex through positive OPK day and day after
- Days 15-16: One more session for coverage; ovulation likely complete
The key insight is that you don't need perfect timing—you need adequate coverage. Having sex 3-4 times during your fertile window gives you nearly the same odds as trying every single day. Focus on the days leading up to ovulation, use OPKs to help identify your surge, and don't stress if you miss a day here or there.
"You don't need to catch the exact moment of ovulation. You need sperm waiting when the egg arrives. Focus on the days before, not the day of."
When Regular Timing Isn't Working
If you've been timing sex correctly for 6-12 months (depending on your age) without success, it may be time to explore whether other factors are at play. Issues like ovulation disorders, blocked tubes, or sperm quality problems won't be solved by better timing alone.
Consider seeing a fertility specialist if you're under 35 and have been trying for 12 months, 35-39 and trying for 6 months, or 40+ and trying for 3-6 months. Basic fertility testing can identify many common issues and inform whether you need treatment beyond timed intercourse.