LH refers to luteinizing hormone. Luteinizing hormone is present in a woman’s system throughout her monthly cycle. There is one specific time during a woman’s cycle, however, in which she will experience what is known as the LH surge. The LH surge is when a woman experiences a sudden, dramatic, and brief increase in the level of luteinizing hormone in her system. The LH surge will typically occur somewhere between 12 and 48 hours to the time that a woman ovulates. For most women, the LH surge will occur right around 36 hours before ovulation. As you can see, the LH surge is directly related to ovulation.

The LH surge is an important part of fertility planning for couples. Couples can measure the woman’s LH surge in order to properly time their attempts at conception. Using ovulation predictor kits or ovulation tests, it is possible for a woman to know when her LH surge is occurring. This lets the woman know that she is about to ovulate in the next 1-2 days. This means that it is then the optimal time to try to conceive, as conception generally will occur no more than 3 days prior to ovulation or one day after ovulation.

It is important that, when a woman is testing for the LH surge, that she use the ovulation test at the same time every day. This doesn’t have to be in the morning in the way that a pregnancy test often does, but rather the ovulation test should be take at the same time every day. This is because a woman’s LH levels might change slightly during the day, and you want to be able to compare one day to the next in an accurate way. It is also recommended that a woman not try to measure her LH surge within a couple of hours after drinking something, as fluids can often dilute the results of the ovulation test to one degree or another.