Charting 101 - Lesson #5: LH / OPKs

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Let’s talk about LH tests, also called OPKs (which stands for ovulation predictor kits). This is Charting 101, lesson #5.

LH tests measure luteinizing hormone in your urine. When LH rises, it signals that ovulation is very likely approaching, usually within the next day or so.

Because of that, LH tests are often used for timing intercourse when trying to conceive. That said, if you’re practicing the Fertility Awareness Method, they’re not necessary. Cervical fluid already shows when fertility is increasing, often earlier than an LH test will.

LH tests can still be a supplemental tool for some people in order to have another way to check that you really are ovulating, but they’re not required for effective FAM charting.

But please remember: LH tests are not a safe or reliable method for pregnancy avoidance. They typically only turn positive just before ovulation, while sperm can survive in the body for up to five days.

So for example, if you had intercourse on a Monday, ovulated on Friday, and your LH test didn’t turn positive until Thursday, pregnancy is still possible from that Monday intercourse.

This is why LH tests are not a primary fertility sign in the Fertility Awareness Method. They don’t show the full fertile window, and they don’t confirm that ovulation actually happened. Indeed, it's sometimes possible to have an LH spike which appears as a positive LH test but without actual ovulation.

Charting your waking temperature and cervical fluid gives you a much more complete and reliable picture, but its understandable that for women who are inexperienced with FAM or who just want additional confirmation, LH tests can provide helpful information.

Follow along for more Charting 101. Next, we’ll go over what a coverline is. And if you’re ready to start charting, download Cyclisity.

As a legal disclaimer, I want to add that this blog post is about the Fertility Awareness Method, not Cyclisity. Cyclisity is an app that helps women chart their cycles but is for informational and educational purposes only. It is not FDA approved as a medical device and does not provide any medical advice. Please consult your physician with any health questions you may have.