Hey collo04

I got this information from the Fertility Friend website...you can do a free charting course (which is excellent) which helps you understand the whole ovulation/conception process...

Luteinizing Hormone (LH) and Your Fertility Signs


Luteinizing Hormone (LH) is the last hormone to peak before ovulation and is the hormone responsible for triggering the rupture of the ovarian sac that releases the egg at ovulation. This hormone can be measured by ovulation prediction kits (OPKs) and fertility monitors that use chemicals to identify its presence in your urine.


The presence of increased amounts of LH in your urine, as detected by OPKs, usually means that you will ovulate within 12-24 hours but this can vary slightly depending on your own hormonal profile. LH is not released all at once, but rather it rises and falls for about 24-48 hours. The LH rise usually begins in the early morning while you are sleeping and it takes 4-6 hours for it to appear in your urine after that. For this reason, first morning urine may not give the best result. Testing mid-day is usually recommended. It is important to follow the instructions of your OPK for maximum results.


Many women like ovulation prediction kits, even though they are not able to confirm or pinpoint ovulation precisely, because they can tell you that ovulation is imminent. It is important, however, not to rely exclusively on OPKs for timing intercourse and identifying your most fertile time. This is because you may already be fertile before your OPK turns positive. You may like to use them, however, to cross-check your other fertility signs and to offer additional clues about impending ovulation. They may be especially useful if you have ambiguous charts. If your cycles are irregular or very long, OPKs may be very costly because you may need to use several tests to be sure to catch the LH surge.