How Soon After an LH Surge Do You Ovulate?

By Susan Revermann
Over-the-counter ovulation tests detect the presence of the luteinizing hormone.

Timing is the key component during family planning. Monitoring your monthly cycle and hormone fluctuations not only keeps you up-to-date on what’s going on in your body, it can increase your chances of conception if you incorporate this knowledge into your baby-making efforts. Knowing when you have a luteinizing hormone (LH) surge will help you determine your ovulation time frame more accurately.

Definition of LH Surge

The luteinizing hormone is one of the most important hormones that come into play in the days that lead up to ovulation. An LH surge occurs when this hormone is released into the body by the pituitary gland. The pituitary gland gets the signal to release this type of hormone from your hypothalamus. This area of the brain is your main hormone regulator.

LH Role in Ovulation

The presence of the luteinizing hormone signals to your mature egg that it’s time to break through your ovarian wall. According to the American Pregnancy Association, the egg bursts through your delicate ovarian wall within 24 to 36 hours after you have an LH surge. Once the egg is released, it travels down the fallopian tube and is available for possible conception. For most women, this process of events occurs somewhere between day 12 and day 16 of the menstrual cycle.

Detecting Your LH Level

You can determine your LH level with two main methods. The first and least invasive is an over-the-counter urine ovulation predictor test. Depending on your budget and preference, you can purchase an ovulation test strip kit, a digital ovulation test or a fertility monitor kit. These are quicker and less expensive than your second alternative, the blood test. Medline Plus indicates that your health care provider can order a blood draw to check your hormone levels on a specific day of your menstrual cycle.

LH Surge and Conception

Once you know you’ve had an LH surge, you can time your conception efforts. WebMD recommends having sexual intercourse a few days prior to your estimated ovulation date, as well as on that day, to increase your chances of conception. Sperm can survive inside you for up to six days, while your egg has a much shorter survival time frame -- 12 to 24 hours. After that, the egg disintegrates and is no longer available for fertilization.