The LH surge signals you are about to ovulate. Identifying this moment can be critical to increasing your chances of conception.
The menstrual cycle is complex. Hormones rise and fall, working together to prepare the body for pregnancy. Once the body reaches ovulation, when one of your ovaries releases an egg, there’s a short window of time for it to be successfully fertilized by sperm. That’s why it’s helpful to understand your menstrual cycle to pinpoint when you’re most fertile if you’re trying to get pregnant.
The LH surge is an important marker in the menstrual cycle, signaling that you are about to ovulate and reach peak fertility. If you are trying to get pregnant, this is when you’ll want to have unprotected intercourse as it gives you the best chance of conception. However, your fertile window includes the days leading up to the LH surge since sperm can live in your body for up to 5 days (1 ). So while the LH surge is your most fertile point during your menstrual cycle, having sex before and after the LH surge also increases your chances of pregnancy. Here’s what to know about when to have sex after the LH surge.
What is the LH surge? During your menstrual cycle, estrogen and progesterone levels rise to thicken the uterine lining and support the development of a mature egg. Once estrogen reaches a certain level, it activates the release of luteinizing hormone (LH). This hormone, secreted by the pituitary gland, triggers the ovary to release the egg to be fertilized. Since the LH surge comes right before ovulation, it’s an indicator that you are about to ovulate and reach peak fertility, when you have the greatest chance of conception.
>>MORE: What Is Late Ovulation (And Can It Affect My Ability To Get Pregnant)?
How long does the LH surge last? Women can experience a gradual onset LH surge or a rapid onset LH surge (2 ). If you have a gradual onset LH surge, you may see positive ovulation test results across multiple days before reaching your LH peak day (where you have the highest concentration of LH). The three common types of gradual onset LH surge are:
Single peak: When your LH steadily rises and peaks. You’ll see the ovulation test line get darker and then lighter once it descends back to its baseline. Plateau: You’ll get multiple positive results with similar darkness before ovulation. Once the test strip gets lighter again, the last positive result is your peak day. Biphasic/multiple peaks: You may experience two or more spikes during your LH surge. Since it’s difficult to know which spike is your peak, you should have sex on each spike (3 ). In a rapid LH surge, the peak occurs quickly, sometimes within a few hours. You'll likely see one positive ovulation test over multiple days of testing. If you haven’t been able to find your LH peak, test twice a day as you near ovulation, as you might have rapid onset LH and missing your LH peak. The intensity of the test line on traditional ovulation tests will indicate where you are in the surge, whether at the beginning or peak. You may also experience multiple peaks due to stress or hormonal imbalances, in which case, the last highest LH peak is the peak day that signals ovulation is about to occur. The LH peak is your most fertile moment in your cycle.
Identifying LH surge and timing for sex At-home ovulation predictor kits can help identify LH surge to indicate when you are most fertile. Since the LH surge only lasts about 24 hours or less, it’s important to test early to avoid missing it. Once released from the ovary, the egg lives only 12 to 24 hours. However, your fertile window is longer because sperm can survive in the body for up to 5 days. Therefore, having sex before ovulation so that sperm is already in your body when you ovulate can increase your chances of pregnancy.
Traditional ovulation tests measure the LH hormone in your urine. Once LH levels peak and reach its highest concentration, it means that you are about to ovulate, usually within the next 36 hours. If you receive a positive result, this is when you want to have sex since it signifies you’re in peak fertility. Experts recommend having unprotected sex two to three times over the next 24 to 48 hours (4 ). If you get a negative result, continue testing once or twice a day as you may ovulate later than expected.
Irregular cycles and health conditions like PCOS can impact your LH surge and result in false positives. In these cases, an LH surge can occur and no egg is released (6 ). Furthermore, traditional tests also measure LH based on “standard” hormone ranges, and it’s common if LH levels are outside of the range due to fertility medications or reproductive health conditions. However, multi-hormone ovulation tests, like Oova, measure multiple hormones to track your fertility. Oova’s at-home, urine-based hormone test analyzes your LH, estrogen, and progesterone levels and filters variables that interfere with traditional tests. It can accurately predict ovulation for individuals with consistent menstrual cycles and people experiencing reproductive health conditions that cause irregular cycles. If you experience irregular cycles, hormone imbalances, or health conditions, it’s important to consult your doctor.
>>MORE: Should You Have Sex Twice a Day During Ovulation?
When to have sex after LH surge: the bottom line Your fertile window includes the five days before ovulation and the 24 hours after you ovulate in which you have the greatest chance of conception. Having unprotected sex throughout your fertile window including the days leading up to the LH surge, maximizes your chances of getting pregnant. However, once you identify the LH surge, you should have unprotected sex as soon as possible, as you’ve reached peak fertility. If you have irregular cycles or reproductive health conditions, this can interfere with ovulation tests and can make it more difficult to identify ovulation. In such cases, multi-hormone ovulation tests can help along with consulting your doctor. Understanding your cycle is crucial to give you the best chances at pregnancy.
