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Your LH surge and ovulation are two of the most vital aspects of your menstrual cycle and overall fertility. But sadly, many women misunderstand this complex relationship.
And for good reason. LH surges and ovulation vary from woman to woman and cycle to cycle.
There’s no one-size-fits-all answer. But keep reading. In this article, you’ll learn exactly how LH surges work and how you can track LH during your cycle.
Before we dive into all the details though, let’s briefly review what your LH surge is.
What is LH Surge?
LH surge refers to the rise in your luteinizing hormone. Levels of this hormone are generally low most of your menstrual cycle. But LH starts rising between 24 and 36 hours before ovulation. And you ovulate about 8 – 20 hours after your LH levels peak.
This is why many women track their LH surges. Because knowing when your LH surge occurs can help predict ovulation. But there is a lot more to it than that.
Before you can truly understand how LH triggers ovulation, let’s make sure you know how to identify an LH surge.
Takeaways
- Your LH surge (a spike in luteinizing hormone) is what triggers ovulation.
- LH surges can occur in various patterns. These include rapid spike, double surge, biphasic surge, multiple surge, and plateau type.
- When testing for LH using an OPK, the alpha LH can cross-react with other hormones. The alpha subunit of LH is the same as the alpha subunit of FSH, TSH, and hCG.
- You can use an OPK or fertility monitor to track your LH surge at home.
- Other signs of ovulation included increased sex drive and BBT, higher cervix, and egg-white cervical mucus.
- Confirm ovulation using Inito to track your PdG levels along with monitoring your fertile window by measuring LH, estrogen, and FSH levels.
- LH surges don’t always mean ovulation. And if you become pregnant, your LH levels remain around their baseline level.
What does an LH surge look like?
Until recently, the consensus was that an LH surge was seen as a single rapid spike. That’s actually not the case at all though. Current studies show that LH can surge in various patterns and what’s considered high LH for one woman may not be high for another woman.
So, let’s go over all the LH patterns and levels that are possible in ovulatory cycles.
Rapid spike (single LH peak)
For a long time, this was thought to be the only type of LH surge. If you were to read an older article about LH surges and ovulation, this would be the type it referred to. But nowadays, we know that only less than 50% of cycles actually have a single “short surge” pattern like this. And guess what, these are normal!
Double LH peak
One type of double LH peak occurs when you have an LH surge on two separate occasions. These surges could be up to 3 or more days apart.
Read More: Two LH Surges a Week Apart: What Does it Mean?
Biphasic LH Peak
Another type of double LH surge where LH rises one after another is called a biphasic surge. With a biphasic surge, there will be an initial spike in LH. This first surge is followed by a decrease and then another increase in LH levels the very next day. The second peak may or may not be higher than the first peak. Recent studies reveal that 44% of cycles follow this “two surges” pattern.
Plateau peak
In some menstrual cycles, luteinizing hormone levels may peak for a few days and then decrease. This pattern makes it difficult to predict ovulation since the LH remains high for 2 – 3 days. But this variation is observed in less than 20% of cycles.
Multiple peaks
This is a surge pattern that involves more than two LH surges over the course of one menstrual cycle. Most times, having multiple surges is completely normal. This can happen about 8% of the time.
Other times, having multiple surges can be a sign of an underlying health condition. These could include hormonal regulation disorders and other conditions like PCOS or anovulatory cycles.
If you have an anovulatory cycle (one where no egg is released), despite having multiple LH surges, be sure to consult your doctor. This could be a cause for concern. The only way to confirm you ovulated is to track your progesterone or PdG levels. More information on this later in the blog.
Read More: LH Levels & Surges: What Does a ‘Normal’ LH Level Look Like?
Now that you have a better understanding of LH surge patterns, let’s take a closer look at the makeup of LH.
Alpha LH vs. Beta LH
One thing you may not realize about LH is that it has two subunits: alpha and beta. This is arguably one of the most overlooked aspects of LH. Yet, knowing the genetic makeup of LH is critical. Especially if you are using LH to track your cycle and fertile window.
So here are the details. LH, hCG (human chorionic gonadotropin), FSH (follicle-stimulating hormone), and TSH (thyroid-stimulating hormone) have similar components.
All four of these hormones are glycoproteins, and each contains an alpha and a beta subunit. The alpha subunits of LH, hCG, FSH, and TSH are identical. But the beta subunit of each is different. And it’s this beta subunit that distinguishes each of these hormones biologically.
Confusion comes into play when you use an ovulation predictor kit that tests for alpha LH. And unfortunately, many test strips on the market test for alpha LH instead of beta LH.
On a urine test strip, alpha LH may cross-react with other hormones like FSH, TSH, or hCG. If you have no knowledge of the molecular makeup of LH, you may be misled by the result of your LH test strip without even knowing it.
To illustrate this even further, take a look at the alpha versus beta subunits in the image above. The light blue represents the alpha subunit for each hormone. You will notice that this subunit looks exactly alike for LH, FSH, TSH, and hCG.
So if you have high FSH or TSH levels when testing with an OPK, the test will report those levels as LH only. This could get a false positive result, making you believe you’re having an LH surge when you’re not.
Whereas if you were to test your LH with a fertility monitor like Inito, then you would get accurate results since it measures beta LH.
In the chart below, you can see the difference between alpha and beta LH levels. This can help you track your true LH.
How does your LH surge initiate ovulation?
As with other incredible outcomes, ovulation is the result of a team effort. Your hypothalamus, pituitary gland, and ovary all work together to ensure that ovulation occurs.
Here’s a quick rundown of how ovulation works and what role your LH surge plays in the process.
We’ll start from the beginning. First, a part of your brain called the hypothalamus releases GnRH (gonadotropin-releasing hormone). This happens in a pulsating fashion. This rhythmic pulsing then triggers FSH to flow from the anterior pituitary gland.
FSH then works to stimulate the ovarian follicles (which house the maturing eggs). An ovarian follicle has three key cells: theca cells, granulosa cells, and the oocyte (the developing egg).
The matured dominant follicle starts releasing estrogen to build the uterine lining. Once your estrogen levels have peaked, it signals the anterior pituitary gland to release LH. This is called the LH surge, and it cues ovulation by telling the mature follicle to release the egg. You will typically ovulate about 24 to 36 hours after the start of your LH surge.
Once you ovulate, the follicle that released the egg becomes the corpus luteum. If you get pregnant, LH and hCG help stimulate the corpus luteum to secrete more progesterone.
This leads us to the next point about LH surges, which is how you can track them accurately at home. So keep reading!
How to detect your LH Surge?
We are lucky to live in an age when there are a lot of resources that make it possible to track ovulation at home.
If you go way back in time, the only way to test for ovulation was through a blood test. These can obviously get quite expensive. Not to mention inconvenient.
So in 2024 and beyond, here are your best options for tracking your LH surges in the comfort of your own home.
Ovulation Predictor Kits (OPKs)
Ovulation kits are very accessible. You can find them in many pharmacies as well as through online retailers. When you use an OPK, you will urinate in a cup and then use a strip to test for LH levels in your urine.
Typically, you test once or twice daily throughout your menstrual cycle. This consistency allows you to have the best chance of catching when your test line indicates an LH surge.
OPKs can be a convenient method for tracking your LH. But keep in mind, as mentioned earlier, many OPKs test for the alpha subunit of LH. Be mindful of this and try to opt for an OPK that tests for beta LH instead.
OPKs do not measure PdG as well which is the sole indicator that you have actually ovulated.
Read More: How Accurate Are Ovulation Tests?
Fertility Monitor
Another method to consider for tracking your LH surge is an at-home fertility monitor. Inito’s monitor gives you accurate data for four sex hormones (estrogen, beta LH, FSH, and PdG) on just one test strip.
The first part of the monitor works similarly to an OPK. You will still need to dip a test strip into your urine. But the second part of the process is more advanced. You’ll then insert that test strip into a monitor. The monitor connects to your smartphone and gives you a numerical value for each of the four hormones, including beta LH.
Not just that, Inito also helps confirm ovulation by tracking your rise in PdG levels. PdG is a urine metabolite of progesterone which rises only after you ovulate.
This method can give you a more comprehensive picture of how your cycle is progressing.
Other signs of ovulation besides LH surges
Most women know that they can track their LH surge to help predict when ovulation is near. But there are also a few other signs that you can look for to track your most fertile window.
Here are four other ovulation signs to keep an eye on:
- Cervical mucus: When you are about to ovulate, the consistency of your cervical mucus changes. It will be an egg-white consistency. This is because this consistency helps with transporting the sperm to its final destination.
- Increased sex drive: Your body is biologically cued to feel extra frisky around the time you are most likely to conceive. This is why you may notice an increased sex drive just before ovulation.
- Change in cervical position: During most of your menstrual cycle, your cervix is lower and is firm to the touch. But when ovulation is near, you may notice your cervix soften and rise higher. If you insert your finger, you may notice it would be high and wet to touch.
- Increase in basal body temperature: Ovulation often causes your basal body temperature (BBT) to rise by 0.5 to 1 degree Fahrenheit. In order to test for this, you would need to take your temperature at the same time each day and record it. Then you can see if there is a noticeable increase around the time you expect ovulation.
Keep in mind that you may not experience all of these signs. And they are by no means an exact science. But in tandem with a fertility monitor or OPK, they can help give you an idea of when to expect ovulation.
While LH can be a helpful predictor of ovulation, it doesn’t guarantee ovulation. Keep reading for why.
An LH surge doesn’t always indicate ovulation
Just because you see signs of an LH surge on an OPK or even your fertility monitor, it does not necessarily mean you definitely ovulated.
Here are some reasons why this is the case:
- For some cycles, you may experience more than one LH surge. This could be a double surge (two surges) or a multiple surge (more than two spikes). This means that some of the surges that your test picks up won’t be the true surge that leads to ovulation.
- You could have an LH surge that attempts to trigger ovulation but that is unsuccessful. This means you would see a noticeable spike in your LH levels, but they aren’t high enough to cause your body to ovulate. The amount of LH needed to induce ovulation varies from woman to woman and cycle to cycle.
- Your ovulation test could give you a false positive result. Since alpha LH can cross-react with other hormones on your test strip, you may get a reading that falsely detects a surge.
LH surge and pregnancy
If you become pregnant, your body will have increased levels of progesterone as well as hCG. When these two hormones are high, your LH levels will remain low.
This can be confusing if you use ovulation tests. Because again, many of these tests measure alpha LH instead of beta LH.
If you remember the image you looked at earlier, this can give you a false positive LH result. This is due to the test picking up on hCG levels that are cross-reacting with the alpha LH.
FAQs
Your LH surge could last anywhere from a few hours to a few days. It really depends on your unique cycle. You could have a short surge one cycle and then a longer one the next. More and more studies are finding that there is a lot of variability when it comes to LH surges.
Again, there is no true “normal” for LH levels. A particular LH level for one woman may trigger ovulation but the same LH level may not trigger ovulation for another woman. One study that followed 40 women found that the general range of LH levels during a surge was 6.5 – 101 mIU/ml.
Once your LH begins surging, you will likely ovulate about 24 – 36 hours later. But remember that not all surges are enough to trigger ovulation. And sometimes you can get a false positive LH surge reading with OPK test strips.
The best way to confirm ovulation is by testing your progesterone levels. Once you ovulate, your progesterone will rise. Inito’s fertility monitor can help you track your PdG (urine metabolite of progesterone) levels to confirm ovulation.
It is possible to ovulate the same day as your LH surge, but it’s unlikely. This is because the LH surge is what cues your ovary to release the egg. So once LH starts rising, it typically takes a day to a day and a half for ovulation to occur.
When your LH levels spike, it triggers the rupture of your mature ovarian follicle. And then soon after, the follicle will release the egg.
Yes, LH levels do drop after you ovulate. One study found that LH levels were about 7.7 times higher than your baseline level. So, once you ovulate, your levels would go back down to whatever your baseline LH amount is.
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