All about Luteinizing Hormone

What is LH and why measure?

When looking to pinpoint the fertile window many women choose to track their levels of Luteinizing Hormone or LH for short. For a woman, increasing levels of this hormone are a good indication of the approach fertile window and ovulation.

LH is created by the pituitary gland and can be found throughout the cycle at low levels. Around the time of ovulation LH will increase, this surge of LH is what causes the most mature egg to be released. It’s for this reason that we can use the levels of LH to track ovulation.

How can I test for an LH surge

Many women chose to track LH using LH test strips, these are also known as Ovulation Predictor Kits, or OPK’s for short. OPK’s measure the levels of LH in the urine and are usually held in the urine stream or into a sample of urine but each test varies so always best to check the specific instructions that come with your kit.

These will first detect the increase in LH and then later the peak LH. The first increase in LH normally suggests the beginning of the fertile window, although some conditions like Polycystic Ovary Syndrome (PCOS for short) and endometriosis affect these levels and make pinpointing the fertile window a little harder.

The test strips themselves can vary in how they show your results, so you’ll need to check the instructions. Most OPKs have two lines, when you see one line the test is negative. When you see two lines, the test can still be negative or can be suggesting a high or a peak level of LH. Unfortunately these tests can be quite difficult to read the difference between high and peak. (Femometer’s Ivy can intelligently read and record your LH levels, giving you a numerical value for your reading in ap, whilst simply telling you Low, High and Peak on the device).

When to use LH tests

LH levels can vary massively from woman to woman. For this reason we suggest you begin testing at a certain point in your cycle. We work this out using calculations about your cycle and period length. 

We first suggest you test once a day and then when you see a positive test you should test every 4 hours to pinpoint ovulation, which usually happens 24-36 hours after your peak reading and once your LH levels have reduced. Femometer will remind you to start testing and help you record and read whether your test is high or peak. Learning to read your cycle and symptom patterns you will be able to spot your fertile window and ovulation more easily.

How to use LH testing for pregnancy.

Women who are trying to get pregnant should time intercourse once they see an increase in LH, and continue to have unprotected sex until after they see the LH peak. This ensures that the sperm are waiting in the uterus and fallopian tubes when the egg is released. Some couples are able to have sex every day through the fertile window, but it’s also fine to have sex every other day. Men who have a low sperm count are often advised that every other day is better than every day to allow time for sperm to increase in between each baby-making session.

Things to be aware of when testing LH

LH testing can be fiddly and a bit confusing sometimes, we’ve tried to make it easier by automating your reading and recording and by helping you to time your tests. Here are a few other things you may want to keep in mind. 

Women with PCOS can have raised levels of LH throughout their cycle, this can make it more difficult to pinpoint the fertile window and ovulation using LH tests alone.

It’s quite easy to start testing too late, you may miss you peak and you won’t know when you’ve ovulated unless you’re also tracking symptoms and BBT.

Women who are approaching menopause may have raised levels of LH throughout their cycle.

Drinking too much water before taking a test and using the first-morning urine can also affect your LH test results.

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