Trying to Get Pregnant? Here’s When to Have Sex.

So, you and your partner are ready to get pregnant. Congratulations!

You probably know what must happen next: sperm must meet egg. For most couples, getting pregnant comes down to having sex around the time of ovulation. This is the time when an ovary releases an egg. As an ob-gyn and reproductive endocrinologist, here’s what I tell my patients who are trying to understand ovulation and how to get pregnant.

Get to know your menstrual cycle.

To get pregnant, you need to know when ovulation happens. You are most fertile around the time an egg is released, and this is when you should plan to have sex.

For most people, the easiest and least expensive way to figure out when you’re ovulating is to track your periods on a calendar. Ovulation typically happens about 14 days before your period starts. This is rather consistent from person to person, no matter how long your menstrual cycle is.

Next, you’ll want to understand how the days of the menstrual cycle are counted. A menstrual cycle lasts from the first day of your period to the first day of your next period. So if your period starts on July 1, that’s day 1.

From here, determining your most fertile days takes just a little bit of math. If your cycle is normally 21 days long, then you likely ovulate around day 7 (21 minus 14 equals 7). If your cycle is on the longer side, say 35 days, you ovulate around day 21. If your cycle ranges between 26 and 28 days long, then ovulation happens between days 12 and 14 in any given cycle.

It also helps to notice changes in your body. Of all the methods to self-detect ovulation, monitoring cervical mucus tends to be the most reliable. Cervical mucus is a type of vaginal discharge: the mucus comes from your cervix and exits through the vagina. This mucus changes throughout the month and peaks 1 to 2 days before ovulation. At this point in your cycle, you may notice a clear vaginal discharge that feels thin and stretchy.

There is no foolproof way to calculate your fertile days. But knowing the pattern of your menstrual cycle and changes in your cervical mucus can give you a pretty good sense of when to have sex.

You don’t need to have sex every single day.

People who are trying to get pregnant often believe there is an ideal moment when they must have sex. In fact, the window of fertility is much wider than this—about 6 days each cycle. This is because sperm can live in a woman’s body for as long as 5 days, while an egg can survive for about 12 to 24 hours after ovulation. So you can have sex up to 5 days before ovulation or 1 day after and still get pregnant.

For the best chance of getting pregnant, research suggests you should have sex every day or every other day during this 6-day window. If you and your partner are happy to have sex every single day of the month, that’s great. But you don’t need to. You don’t want to put so much pressure on yourselves that sex becomes stressful or unenjoyable.

You don’t need to invest in extra tools—unless you really want to.

Today there are countless smartphone apps, devices, and other tools on the market designed to help you get pregnant as soon as possible. These range from free period tracking apps to ovulation predictor kits you can buy at the drugstore for about $20. Some more sophisticated devices can cost hundreds of dollars.

These tools can certainly help you track and notice trends in your menstrual cycle. They’re also useful if you and your partner only have sex once or twice a month, in which case you really need to pinpoint the best time to get pregnant. Some people feel empowered having so much data at their fingertips. If that’s true for you, then by all means use this technology.

On the other hand, I’ve seen how fertility trackers and ovulation predictors can create a sense of urgency around getting pregnant. Many people find the information overwhelming and become fixated on doing everything “just right.”

What’s more, these tools don’t work for everybody, and the results are not always accurate. For example, if you have highly irregular periods, trying to predict ovulation at home is not going to be worth your time or money. (Instead, seek advice from an ob-gyn or reproductive endocrinologist. Highly irregular periods may be a sign you are not ovulating, and you may need medications that can help make you ovulate.)

There’s also concern about period tracking apps and the privacy of your health data. These apps are not covered by HIPAA, the law that protects the personal health information that you share with doctors. If you’re thinking about using an app, first review how it would store and share your data.

Here’s my take: These tools can be nice to have but are not necessary for most couples. The costs may outweigh the benefits, especially if they create anxiety. Use the technology only as much as it suits you—which could be not at all.

Know when to talk with your ob-gyn.

It’s normal to not get pregnant right away. More than half of healthy couples get pregnant within the first 6 months of trying. This can be hard to accept when all you want is to start or grow your family, I understand.

That said, if you’re under 35 and have been trying for an entire year without success, contact your ob-gyn or see a reproductive endocrinologist. The problem is unlikely to be that you’re not having sex often enough or at the right time. (If you’re 35 to 39, you should seek help after 6 months of trying. And if you’re 40 or older, you may want to seek help even sooner.)

[Having a Baby After Age 35: How Aging Affects Fertility and Pregnancy]

The same goes if you have a known condition that makes it harder to get pregnant, such as a history of endometriosis, polycystic ovary syndrome (PCOS), or prior pelvic surgery. In these cases, it’s a good idea to see a fertility specialist early on.

For most couples, the prospect of getting pregnant can feel both anxious and exciting. Hopefully, you’ll succeed within a few months. If you don’t, there are ways to figure out what’s going on and improve your chances. Either way, your ob-gyn or reproductive endocrinologist will be there to help guide you through this journey.

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This information is designed as an educational aid for the public. It offers current information and opinions related to women's health. It is not intended as a statement of the standard of care. It does not explain all of the proper treatments or methods of care. It is not a substitute for the advice of a physician. Read ACOG’s complete disclaimer.