But don’t let those odds stop you from having sex! There are a few reasons to have baby-making sex even if you think you already ovulated. First, you may be mistaken about your exact day of ovulation. And second, sex after fertilization may boost your odds of pregnancy.
The Fertile Window
Ideally, if you want to get pregnant, you need to have sex before you ovulate. If you 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. Sperm can live for a few days in your cervix and fallopian tubes, but an egg must be fertilized soon after it’s released. So your odds are better if sperm are ready and waiting for an egg they can fertilize, rather than the other way around. There have been several research studies on the odds of conception at various stages of the menstrual cycle. These agree that the best odds of conception are the day before and the day of ovulation. But it’s not 100% clear how likely you are to conceive once ovulation has passed. 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.
One day before ovulation: 21% to 35%On ovulation day: 10% to 33%One day past ovulation (1DPO): 0% to 11%Two days past ovulation (2DPO): 0% to 9%
A more recent study that looked at the probability of pregnancy from intercourse throughout the menstrual cycle found the highest probability on day 13 (one day before ovulation) in people with regular cycles.
How Long After Ovulation Can You Conceive?
For you to get pregnant, you egg needs to be fertilized while its still viable. This window of time is 12 to 24 hours after ovulation. Remember that ovulation test sticks turn positive when you are about to ovulate. A positive result means you’re likely to ovulate within 24 to 36 hours. You can’t confirm exactly when ovulation occurs with these tests, so don’t count you egg out after you see a positive. Assume you’re fertile 72 hours after your positive. To pinpoint ovulation, you would need to chart your basal body temperature daily and check for a spike in temperature. The spike indicates that ovulation has already happened. Once you see the spike, you can consider yourself fertile for 24 hours. Fertilization is only the first step in what could be a successful pregnancy. 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 considered pregnant until the embryo implants itself into the uterine lining.
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 perfect. So even if you think you’ve already ovulated, and missed your fertile window, you may still be in that window. It doesn’t hurt to try! There are many ways to detect your most fertile time, including:
Body basal temperature charting Tracking cervical mucus changes Using an ovulation predictor test Using a wearable fertility monitor
It may be a good idea to use a combination of methods so that you can better pinpoint your fertile window. For example, if you see fertile cervical mucus and you’re ovulation predictor test is positive, you can be more confident that now’s the time. You can also cover your bases by starting to have sex every day or two from the last day of your period to a day or two after your basal body temperature rises. There’s no harm in having frequent sex all month either, and it might even help with sperm quality. If you are trying to pinpoint ovulation day by measuring urinary levels of the hormone LH (like you do with an ovulation predictor test), the results can be quite accurate (over 90%). But you do have to keep purchasing kits and/or test strips.
Sex After Ovulation May Help With Implantation
There’s another reason to have sex even if you’ve already ovulated: It may improve your odds of implantation. An older 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. The theory is that semen may play a role in embryo health and development. While more recent research has failed to find evidence of this effect, a 2020 study reported that having sex around the time of implantation (in people not undergoing fertility treatments) doesn’t increase or decrease the likelihood of implantation and successful pregnancy. This suggests that having sex post-ovulation is unlikely to harm the chances of implantation.
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.
