chances of getting pregnant after one time unprotected during ovulation?

Your Odds of Getting Pregnant If You Have Sex After Ovulation
By Rachel Gurevich, RN
Rachel Girevich

Updated on November 03, 2021
Medically reviewed by Andrea Chisholm, MD
Couple in bed

Verywell / Photo Illustration by Julie Bang / Getty Images
Table of Contents

Conceiving From Sex After Ovulation
Timing of Post-Ovulation Conception
Why Have Sex After Ovulation?
Ovulation Day Errors

Your chance of getting pregnant after ovulation is small. One day past ovulation, your odds are between 0% and 11%.1 But don’t let that stop you from having sex!

You may be mistaken about your exact day of ovulation. Plus, sex after fertilization may boost your odds of pregnancy.
Conceiving From Sex After Ovulation

Ideally, if you want to get pregnant, you need to have sex before you ovulate. If you were confused about this before—and thought sex needs to come after ovulation—you’re not alone. Many people don’t realize that the best time to have sex to get pregnant is before, not after, ovulation.2

However, let’s say you think you’ve already ovulated… is there any point in having sex, just in case? Yes.

There have been several research studies on the odds of conception at various stages of the menstrual cycle. Everyone agrees that your best odds of conception are the day before and the day of ovulation. But not everyone agrees on how likely you are to conceive once ovulation has passed.

Based on a number of studies, your odds of getting pregnant from having intercourse once may be anywhere in these ranges:

21%–35% one day before ovulation
10%–33% on ovulation day
0%–11% one day past ovulation
0%–9% two days past ovulation

These numbers assume that you have sex just once during your fertile window. If you have sex before you ovulate and the day after, your odds will be significantly different (better!) than if you have sex only after you ovulated.
How Often Do You Need to Have Sex to Conceive?
How Long After Ovulation Can You Conceive?

This depends on how you define "conceive." Fertilization of the ovulated egg must take place within 12 to 24 hours. After that, the egg is no longer viable.

But fertilization of the egg doesn't mean you're pregnant. As anyone who has gone through in vitro fertilization (IVF) can tell you, having an embryo (which is a fertilized egg) doesn't guarantee a pregnancy. You're not pregnant until the embryo implants itself into the uterine lining.

Embryo implantation takes place between 5 and 10 days after ovulation. It usually takes another several days before you will get a positive result on a pregnancy test.
Why Have Sex After Ovulation?

There’s another reason to have sex even if you’ve already ovulated: It may improve your odds of implantation. A small but interesting study looked at the effect sexual intercourse has on pregnancy success and IVF. In this study, one group of couples had sexual intercourse around the time of embryo transfer. The other group abstained from sex.

The initial pregnancy rates between the groups were not that different. However, the number of people who were still pregnant at 6 to 8 weeks was significant.

Of the group that had sex around the time of embryo transfer, 11.01% were still pregnant at 6 to 8 weeks. As for those who did not have sex around embryo transfer, only 7.69% were still pregnant at 6 to 8 weeks.3 The theory is that semen may play a role in embryo health and development.
Ovulation Day Errors

Keep in mind that ovulation day errors can occur. You may be wrong about when you ovulated. Most methods of ovulation prediction aren’t extremely accurate. So, even though you think you already ovulated, you may be wrong.

There are many ways to detect your most fertile time, including:

Body basal temperature charting
Tracking cervical mucus changes (the best one to use, per the research!)
Using an ovulation predictor test

Body basal temperature (BBT) charting is often considered to be the most accurate, but it’s not error-free. According to one study, BBT charting predicted the day of ovulation correctly only 43% of the time.2

If you were trying to pinpoint ovulation day by measuring urinary levels of the hormone LH (like you do with an ovulation predictor test), you’d only determine the exact day 60% of the time.
8 Signs of Ovulation That Help Detect Your Most Fertile Time
A Word From Verywell

When you're trying to get pregnant, it can be tempting to worry about whether you're having sex "at the right time." While there are particular days when you're more likely to conceive, sex shouldn't only be about baby-making.

That said, if your only chance to have sex happens to fall after ovulation, it's natural to wonder if it "counts." Whether you think you’ve already ovulated or not, have sex. You may have miscalculated and think you ovulated already when you haven't... or, even if you already ovulated, it's possible sex after ovulation could help along an embryo.