Anyone who has been trying to have a baby 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 women to remain optimistic while waiting to see that positive pregnancy test.
Whether you’ve been trying for a while, or are starting to think about expanding your family, it’s beneficial (and motivational!) to understand your menstrual cycle and to know the best time of the month to get pregnant. One of the ways to optimize your chances is by having timed intercourse.
What exactly 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 get pregnant. It’s an incredibly 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 you know yours if you want the best chances of conceiving. A woman is fertile from about five days before she actually ovulates until 24 hours after ovulation has occurred. If sperm is in the vicinity of an egg during this window 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 around the cervix, but only if cervical mucus is present. Cervical mucus is produced by the cervix due to rising estrogen levels as ovulation nears. Since sperm lives longer, this six-day window gives you the highest chance of success. Basically, if you have sex several times during this time, your chances of pregnancy increase.
“If you have a twenty-five-year-old woman with a 28-day menstrual cycle, then I would recommend for the first six months to be sexually active around day 12 to 14, but I wouldn’t recommend much more,” explains Dr. Ralf Zimmermann, an OB-GYN, reproductive endocrinologist, and medical director at Neway Fertility.
Why timed intercourse works
Your chances of conception can be dramatically improved by the timing of intercourse — assuming you don’t have any issues with your uterus or fallopian tubes and your male partner doesn’t have any issues related to his fertility. Here’s some data on chances of conception:
- There’s a 42% (max) chance of conception on the day before ovulation, the most fertile day of your cycle. (Source)
- On average, 68% of women aged 20-44 will conceive within three months of TTC, and 92% will conceive within 1 year of TTC. (Source
- 45% of people age 25 or younger conceive within one cycle; while 20% of people age 35 or older conceive within one cycle. (Source)
Arguably the most important thing you can do to boost your odds is to track your cycles and time intercourse around ovulation. After all, 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.
While some sources suggest you should be having intercourse every other day in this window, there aren’t empirical studies suggesting what the optimal intercourse frequency is, but it’s likely that more frequent = better.
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.
Getting the timing right
Many women have a lot of trouble actually knowing when their fertile window is open for business. The best approach when just starting out, according to Dr. Zimmermann, is to begin having sex on cycle day 10 and continuing every other day until ovulation and then again one day after ovulation. Day 10 is a good starting point because estrogen levels are high and the uterine lining should be getting pretty thick.
Ovulation tracking can give you a better picture of that fertile window. Ovulation predictor kits like the Modern Fertility Ovulation Test work by detecting a rise in LH, or luteinizing hormone, in your urine. This LH surge comes 24-48 hours before ovulation.
Each brand of test is 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 like the Modern Fertility Ovulation Test, 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. (Side note: Standard ovulation tests that give you a negative/positive result don’t work for 1 in 10 people with ovaries with LH levels that fall outside of “normal” ranges.
Dr. Zimmermann recommends using the tests in the morning and when you get your first positive, to continue to test for another day or two to make sure the positive disappears or becomes negative again so that you know that the ovulation test is accurately capturing your LH levels.
Sometimes, it’s helpful to measure progesterone levels at your doctor on day 21 so you know ovulation has really occurred. If the levels are low, it’s suggestive that ovulation didn’t actually take place.
“I’ve had, on rare occasions, patients think the kit was positive and I measured the progesterone level and it didn’t actually work,” he says.
Basal body temperature (BBT) is another method used to track ovulation. The idea is that your resting body temperature (your BBT) rises slightly when ovulation occurs. You have the highest chance of pregnancy two to three days before this increase in temperature occurs. It’s usually used in combination with other tracking methods (like observing changes in your cervical mucus) since you can’t know you’re ovulating until the rise in temperature actually occurs.
For this reason, Dr. Zimmermann doesn’t recommend the BBT method alone for fertility tracking.
“Different women have different thresholds,” he explains, “so under those circumstances, if somebody wanted to just check whether the kit worked — whether they are ovulating — it might be better to go to your OB-GYN and have your progesterone level measured. Then you know 100% that you’re ovulating.”
What if it doesn’t work?
If you’re in your 20s or early 30s and have been trying for a year with no success, if you are over 30 and have been trying for six months, or if you have a medical condition such as endometriosis or PCOS, it may be a good time to seek out help from your OB-GYN or fertility specialist. They can do testing to look into why conception hasn’t yet taken place.
Modern Fertility’s at-home tests and digital tools can help you better understand your ovulation patterns and reproductive health:
- The Modern Fertility Ovulation Test lets you track your luteinizing hormone (LH) levels to predict your two most fertile days. With our test you’ll get more insight than just a positive or negative result — you’ll be able to see your LH change daily and track low, high, or peak levels. This is key for understanding whether you're in your fertile window and approaching ovulation (when you have the highest chances of pregnancy). The tests works ~like magic~ with the free Modern Fertility App where you can scan and log your results using your phone’s camera, as well as track your periods and sex or insemination.
- The Modern Fertility Hormone Test measures the same fertility hormones that a doctor would test in a fertility clinic (for a fraction of the price) and helps you understand how your fertility is changing over time. Our hormone test gives you insight into the number of eggs you have and can help you identify red flag issues — like PCOS or thyroid conditions — that could affect your reproductive health down the line. Each test is customized for you based on your birth control — if you’re not on hormonal birth control you can test up to eight different fertility hormones.
- And if you’re going off birth control to try to conceive? Test for pregnancy and trust the result with the Modern Fertility Pregnancy Test — which is just as accurate from the day of your missed period as leading pregnancy tests, but more affordable. Use the Modern Fertility App to log your results and know the best time to test for pregnancy.