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Anyone who has been trying to get pregnant for more than a few months has probably heard comments from friends and family about all the “fun” involved in the process. (“At least you can have a good time trying!”) Remarks like this are usually well-meaning, but they can also put a lot of pressure on people to remain optimistic while waiting for that positive pregnancy test — even when the waiting feels more stressful than enjoyable.
Whether you’ve been trying for a while or are just starting to think about expanding your family, if your plan is to conceive without medical assistance, there’s one tried-and-true way you can increase your chances of conception: by understanding the best days of the month for getting pregnant and timing intercourse around those days.
While your healthcare provider will likely talk to you about timed intercourse in your preconception visit, consider this article a leg up on the conversation.
Here are the biggest takeaways:
- What exactly is timed intercourse? Planning sex around your “fertile window.” Your chances of getting pregnant increase five days before you ovulate, and you reach peak fertility on the day before and the day of ovulation.
- How can you plan sex during your ovulation window? By tracking ovulation. The most effective way to track ovulation is with an ovulation predictor kit. OPKs measure levels of luteinizing hormone (LH) in your urine. Because LH levels surge 24-48 hours before ovulation, a positive test result signifies that your LH may be surging — and that ovulation is likely around the corner.
- How can you track ovulation without a test? By monitoring physical symptoms like changes in your cervical mucus and basal body temperature (aka fertility awareness methods) and by using an app that takes into account your previous cycles and presumed ovulation days.
- What should you do if timed intercourse doesn’t help you conceive? If tracking signs of ovulation and timing intercourse hasn’t helped you conceive within 12 months if you’re under 35 and six months if you’re over 35, talk to your healthcare provider.
What is timed intercourse?
Timed intercourse is exactly what it sounds like: carefully scheduled sexual intercourse around your fertile window or the time you’re most likely to conceive. It might be a pretty unsexy term, but it actually has a lot of success when done properly.
First of all, let’s talk about the fertile window because it’s important to know yours if you want the best chances of getting pregnant:
- Someone with ovaries has the highest chances of conception from about five days before they actually ovulate until the day of ovulation.
- If sperm is ready to go in the reproductive tract during the time of ovulation, it’s possible to get pregnant.
- Unlike the egg, which only lives for about 12–24 hours after it’s released from the ovary, sperm can live for about five days hanging out in the uterus and tubes — but only if cervical mucus is present. (Cervical mucus is produced by the cervix due to rising estrogen levels as the day of ovulation nears, and you can tell you’ve entered your fertile window when the mucus looks like egg whites.)
As Dr. Nataki Douglas, MD, PhD, a reproductive endocrinologist and the chair of the Modern Fertility Medical Advisory Board, explains it, “We recommend sex every 1-2 days especially during this fertile window [which comes before and during ovulation] because we know that sperm have a lifespan that’s longer than the egg.” Sex during this six-day window (every other day, as Dr. Douglas recommends) gives you the highest chances of sperm meeting up with egg.
Does more sex = better odds of conception? “Anything more frequent than that has not been shown to increase chances of conception and runs the risk of turning sex into a chore, which is the opposite of what it should be,” says OB-GYN and Modern Fertilitiy medical advisor Dr. Jenn Conti, MD, MS, MSc.
How well does timed intercourse work?
Your chances of conception can be dramatically improved by the timing of intercourse — assuming there aren’t other factors that impact fertility at play (like issues with the uterus, fallopian tubes, or fertility hormone levels, as well as male infertility). We know this in part because of our general understanding of the menstrual cycle and conception:
- If you aren’t having sex during the fertile window, your chances of conception are zero.
- Because the chances of conception increase in the five days before ovulation and peak the day before ovulation, you should be having sex within this window if you’re looking to conceive.
- There’s a 42% (max) chance of conception on the day before ovulation, the most fertile day of your cycle.
In one 2003 study, women between the ages of 20 and 44 were taught how to use natural family planning (e.g., monitoring cervical mucus and basal body temperature) when they started trying to conceive (TTC) — meaning they were likely able to get a good grasp on ovulation and their fertile windows:
- 38% of the participants conceived within one month of TTC, 68% within three months, 81% within six months, and 92% within 12 months.
- The American Society of Reproductive Medicine (ASRM) cites that a “healthy” 30-year-old has a 20% chance of conceiving each cycle, while a 40-year-old’s chances are 5% each cycle.
- While the 2003 study’s results aren’t broken down by age, the authors wrote that the difference in age between participants who conceived and who didn’t wasn’t statistically significant.
- What this means: The conception rate per cycle may be higher for people who are paying close attention to the timing of ovulation and their fertile windows.
Timing intercourse during your fertile period is simple and cost-effective compared to other fertility treatments such as in-vitro fertilization (IVF), intrauterine insemination (IUI), or other methods of ovulation induction, so it’s good to try before moving on to other more expensive options — provided there aren’t other factors impacting conception.
Getting the timing right: How can you make sure you have sex during your ovulation window?
Many people have a lot of trouble actually knowing when their fertile window is open for business. So, we’ve rounded up a variety of ways you can pinpoint your fertile window — from the analog to the digital:
1. Ovulation predictor kits (OPKs): Ovulation predictor kits (OPKs) work by detecting a rise in luteinizing hormone (LH) in your urine. This LH surge occurs 24-48 hours before you ovulate, so it’s a biology-backed signifier of your fertile window:
- Each OPK brand different, but some (threshold ovulation tests) will give you double blue lines or a smiley face when you’ve hit your LH surge, while others will actually give you a numerical value of your LH level, which lets you understand whether you’re at low, high, or peak LH as you approach your surge and two most fertile days.
- Standard ovulation tests that give you a negative/positive result don’t work for 1 in 10 people with ovaries who have LH levels that fall outside of “normal” ranges.
Since not everyone has a textbook 28-day cycle with ovulation occurring on day 14, follow these steps to help you catch your surge:
- Start taking ovulation tests a couple days after you stop menstruating, then keep using the OPK until you get a positive result.
- It’s a good idea to start taking tests 19 days before your next period. (After you’ve determined your cycle length, you can subtract 19 from that number and find the correct date.)
- On testing days, you can take a test every 12 hours so you don’t accidentally miss your LH surge.
- Take your ovulation test at the same time each day and don’t drink excessive fluids beforehand (so your urine won’t be too diluted to show accurate hormone levels).
2. Physical signs of ovulation: By monitoring physical symptoms from month to month and using what’s called fertility awareness methods, you can track your ovulation even without a predictor kit:
- The cervical mucus method tracks changes in the appearance, color, and consistency of your cervical mucus throughout your menstrual cycle to signal when ovulation is near and you’ve entered your fertile window.
- Charting your basal body temperature (BBT) — or your body’s at-rest temperature — helps you identify the slight increase that comes at the time of ovulation. You can take your temperature each morning to learn if you’ve already ovulated. Because it only works after ovulation and because many factors can impact your BBT, tracking BBT isn’t a very accurate way to predict your fertile window.
3. Cycle-tracking apps: You can also use an app that tracks your periods and ovulation to predict when your fertile window may arrive:
- Typically, apps count the number of days between the last day you reported being on your period and the first day you report being on your next. Using that info, they can make a prediction of how long your cycle is and when ovulation might come.
- Most apps aren’t accurate on their own in predicting your fertile window — in one 2016 study, only three apps were found to be accurate in that respect.
- Apps that log and track ovulation test results provide much higher accuracy. In fact, using products that measure LH helps you predict ovulation with 95% accuracy.
- While you don’t necessarily need to test LH if your cycle comes like clockwork and you always ovulate on day 14 of your cycle, if it’s important to you to accurately identify your fertile window, self-reporting your menstrual history in an app might not cut it on its own.
What if timing intercourse doesn’t work?
If you’re in your 20s or early 30s and have been trying to conceive for a year with no success, you’re over 35 and have been trying for six months, or you have a medical condition such as endometriosis or polycystic ovary syndrome (PCOS) that can impact fertility, it’s a good time to seek out help from your OB-GYN or fertility specialist. They can test your fertility to look into why conception hasn’t happened yet or help you figure out a treatment plan to make conception more likely.
Dr. Jenn Conti is an OB-GYN and serves as an adjunct clinical assistant professor at Stanford University School of Medicine.