What is an LH surge?

Written by: Dr. Amy Beckley, PhD, Founder and Inventor of the Proov test the first and only FDA-cleared test to confirm successful ovulation at home.

Written on: 1/17/22

what is an LH surge

An LH surge is a critical point in your cycle when trying to conceive.

If you’re new to the trying to conceive world, you may also be navigating new terms, for example, an LH surge. An LH surge is a critical point in your cycle when trying to conceive.

But what exactly is an LH surge and why are they so important? Keep reading to learn more about LH surges and how they can help you on your fertility journey.

What is LH?

Our reproductive hormones control our cycles. Follicle stimulating hormone, estrogen, luteinizing hormone (LH), and progesterone manage when and if our follicles grow, when we ovulate, and when our next period arrives.

At the beginning of each cycle (i.e. the start of our period), all our hormones are low. First FSH increases to promote follicle growth, then estrogen as our ovary chooses a dominant follicle. This contains the egg that will eventually ovulate.

When estrogen reaches a high enough level, your brain gets a signal that a mature egg is ready for ovulation. In turn, your brain sends a luteinizing hormone surge to the ovary to trigger ovulation.

LH is the hormone that should trigger the follicle to rupture, meaning it should cause ovulation to occur. Studies show that ovulation typically occurs about 12-36 hours after an LH surge.

It’s important to note that LH surges don’t always result in ovulation. But, in order for ovulation to occur, you must have an LH surge. More on this later!

What is an LH surge and why is it important?

As we mentioned, an LH surge should trigger ovulation to occur. Identifying an LH surge can be a good indication that you’re about to ovulate!

Because of this, an LH surge can identify your 2 most fertile days, also known as peak fertility. If you’re new to TTC, this is the time to “try.”

You see, conception can only occur when both an egg and sperm are present. Eggs are only viable for up to 24 hours after ovulation, which only leaves sperm a short period of time to actually fertilize that egg.

Sperm, on the other hand, can survive in your reproductive tract for up to 5 days. This means that getting sperm there earlier gives you a better chance at fertilizing the egg once it arrives.

LH surges help us identify our 2 most fertile days in order to time intercourse appropriately. In fact, identifying an LH surge can impact your chances at pregnancy.

Studies show that a primary cause of the inability to conceive in most fertile couples is mistiming of intercourse. LH tracking is an important method that helps us time intercourse in order to maximize our chances at pregnancy.

what is an LH surge

LH tracking is an important method that helps us time intercourse in order to maximize our chances at pregnancy.

How can I track my LH surge?

Luckily, tracking your LH surge is simple with tools like Proov Predict LH tests! LH tests — also commonly called ovulation tests — measure LH levels in urine.

LH circulates through our blood and then gets metabolized by our liver to be excreted in urine. While technically you can measure LH levels in blood, urine testing is typically more advantageous due to its non-invasive nature.

In order to accurately identify your LH surge, we recommend beginning testing with Proov Predict 18 days before your next suspected period. You can start by testing daily but as you near your date of suspected ovulation (about mid-way through your cycle), you may want to test two times per day — once in the morning and once at night.

LH surges can be short so some ovulation tests may recommend testing 2 times per day, depending on the form of LH they measure. However, some tests require first morning urine, so be sure to read the instructions on yours since they may be slightly different.

Please note that our specific instructions here apply only to Proov Predict tests; be sure to read the instructions if you choose to use a different brand of LH test. For step-by-step instructions, reminders, when to test, and numeric hormone levels, we recommend downloading the Proov Insight app to complement your Predict tests!

Once you get that positive LH test, it’s time to get busy. You’ve now entered your 2 most fertile days and intercourse is most likely to result in conception.

what is an LH surge

A positive ovulation test means you’ve entered your 2 most fertile days and intercourse is most likely to result in conception.

Does an LH surge mean that I ovulated?

LH testing provides awesome insight into your cycle and ovulation so you can time intercourse to get pregnant faster. However, like all hormone tests, LH tests have their limitations.

Although LH tests are called ovulation tests, they can actually only predict when ovulation may occur, rather than confirming an egg was actually released. While LH surges are necessary for ovulation to occur, they do not always result in ovulation.

In people with elevated LH levels across their cycles, like in those with polycystic ovarian syndrome (PCOS), a positive LH test doesn’t always indicate a surge that will result in ovulation. Those experiencing other hormonal imbalances or perimenopause may also have surges that do not result in ovulation.

This is why confirming ovulation after it should occur is so important! You can confirm ovulation with Proov Confirm PdG tests — the first and only FDA cleared PdG test to check for successful ovulation at home.

PdG is a urine marker of progesterone that is only present after ovulation occurs. Not only does it confirm that you did in fact ovulate, but it also confirms that enough PdG was produced after ovulation to allow for a higher chance at pregnancy.

LH surges are a critical point in the cycle for anyone trying to conceive. The more you know, the better you can set yourself up for success on your fertility journey!

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“Hormone balance plays a huge role in fertility, and understanding what’s going on with your hormones doesn’t have to be such a mystery.

It’s actually way easier than most people realize.” 

— Amy Beckley, Proov Founder