The evidence is mixed, and no studies have been done on natural conception. It's harmless to try, but don't stress if you need to get up.
This advice is everywhere: after sex, lie still for 15-30 minutes. Maybe put a pillow under your hips. Some people even recommend putting your legs up against the wall to "help gravity" pull sperm toward the egg.
It sounds reasonable. But what does the science actually say?
Why People Think It Helps
The logic goes like this: if you stand up or move around immediately after sex, semen will leak out, taking precious sperm with it. By lying still—especially with your hips elevated—you're keeping the sperm inside longer, giving them more time to swim toward the egg.
There's just one problem with this theory: sperm don't need that much time.
What the Studies Actually Show
Here's where it gets interesting. We don't have any controlled studies on lying down after natural sex. What we have are studies on IUI (intrauterine insemination)—and they show mixed results.
391 women were randomized to either lie down for 15 minutes after IUI or get up immediately. Result: 27% live birth rate in the lying-down group vs. 17% in the get-up group. That's a big difference.
Reported even more dramatic results: 29% pregnancy rate with bed rest vs. 10% without. However, this was a smaller study with some methodological questions.
Found no significant difference between lying down and immediate mobilization. Actually noted a slight trend favoring getting up immediately, though it wasn't statistically significant.
Found 40% pregnancy rate in women who got up immediately vs. 32% in those who rested—the opposite direction! But the difference wasn't statistically significant.
Why IUI Studies May Not Apply to Natural Conception
Important caveat: IUI involves placing sperm directly into the uterus, bypassing the cervix entirely. Natural sex deposits sperm in the vagina, where they must enter cervical mucus to proceed.
With IUI, lying down might help keep the sperm sample from flowing back out of the uterus. But with natural conception, the sperm that matter enter the cervix within seconds—before you could even think about lying down.
In natural conception, sperm enter cervical mucus almost immediately. The rest that leak out weren't going to make it anyway. Lying down doesn't change which sperm reach the egg—it just changes how much semen stays inside the vagina.
What About Elevating Your Hips?
Some take it further: not just lying down, but propping your hips up on a pillow or putting your legs against the wall. The idea is that gravity will help sperm flow "downward" toward the cervix.
There's no evidence this helps.
The cervix isn't positioned directly above the vaginal canal—it's at an angle. And sperm don't need gravity's help; they swim using their tails, propelled by the force of ejaculation. Changing your angle doesn't change the physics of how sperm reach the egg.
"There is no scientific evidence that any position after intercourse improves fertility. Sperm begin entering the cervical mucus almost immediately, regardless of the woman's position."
— American College of Obstetricians and Gynecologists
So Should You Bother?
Here's our take:
âś… Reasons to Lie Down
- It's harmless
- Some IUI studies showed benefit
- It might help you relax
- Good excuse to cuddle
- Reduces post-sex "mess"
❌ Reasons Not to Stress
- No evidence for natural conception
- Sperm reach cervix in seconds
- Some studies showed no benefit
- The "leaking out" part doesn't matter
- Stress is worse for fertility than position
If lying down for 10-15 minutes after sex feels right to you, go for it. But if you need to get up—to pee, to catch a flight, to deal with a crying kid—don't worry about it. You're not sabotaging your chances.
What About the Leaking?
Yes, some semen leaks out after sex. This is called "flowback" and it's completely normal. It happens regardless of position and doesn't mean you've lost all the sperm.
Here's what's actually leaking out: seminal fluid (the liquid part of semen), along with sperm that didn't make it into the cervical mucus. The viable sperm—the ones that entered the cervix—are already on their journey. The rest were never going to make it anyway.
What Actually Matters More
Instead of worrying about lying down afterward, focus on factors that genuinely impact conception:
- Timing: Sex during the fertile window (especially 1-2 days before ovulation) matters most
- Frequency: Every 1-2 days during fertile days
- Sperm health: Fresh sperm beat "saved up" sperm
- Stress management: High stress hormones double infertility risk
- Basic health: Sleep, moderate exercise, limiting alcohol
Know When to Try
Timing beats position every time. Find your fertile window with our free calculator.
Calculate Ovulation →The Bottom Line
Lying down after sex probably doesn't hurt, and if it makes you feel like you're doing something helpful, that's fine. But don't stress about it. Don't cancel plans because you need to lie perfectly still. Don't feel guilty if you jump up to pee.
The sperm that are going to fertilize an egg start their journey within seconds of ejaculation. What you do afterward isn't going to change whether they make it.
Focus on timing. Focus on frequency. Focus on enjoying each other. Those are the factors that actually matter.