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You’ve likely heard about luteinizing hormone and tracking your LH surge to predict ovulation.
But it’s also possible to see rises in LH at other points in your menstrual cycle as well. This could be from LH levels changing in reaction to other hormones like progesterone or a small LH surge that may help boost your chances of implantation.
There’s more to the story behind LH surges though. So keep reading to learn about what to expect with an LH surge before a period or in early pregnancy.
Takeaways
- It is possible to have an LH surge before your period after you’ve ovulated.
- Normal luteinizing hormone levels differ quite a bit from person to person. But here’s a general idea of what to expect.
Follicular phase LH levels: 1.68 – 15 IU/mL
Mid-cycle peak LH levels: 21.9 – 56.6 IU/mL
Luteal phase LH levels: 0.61 – 16.3 IU/mL - Aside from ovulation, luteinizing hormone (LH) levels surge for a couple reasons. The most likely reasons for these additional surges are decreasing progesterone levels or LH boosting to help with implantation.
- It’s also possible to get false positive test results on ovulation predictor kits due to cross-reactivity with the pregnancy hormone hCG. False positives can also happen if you have PCOS, anovulatory cycles, or if you are on certain medications.
- You can have an LH surge before your period and still be able to get pregnant.
- If you have any concerns about your LH levels, be sure to schedule an appointment with your healthcare provider.
What’s the normal trend for LH levels?
It’s tricky to pinpoint exact numbers for normal LH levels in females. Levels of this hormone can vary quite a bit from person to person.
That said, most women will follow a general LH pattern. And there are some standard ranges you can use as a reference point for different phases of your menstrual cycle.
In the table below, you’ll see what LH levels (on a blood test) may look like depending on where you’re at in your cycle.
Phase of cycle | Range of serum LH (in IU/mL) |
Follicular phase | 1.68 to 15 |
Mid-cycle peak | 21.9 to 56.6 |
Luteal phase | 0.61 to 16.3 |
Keep in mind that these values are for blood LH levels (not urine). And also remember, that these should be used as a reference. They’re not the end-all, be-all of what’s “normal.”
What’s more important to understand is how LH levels rise and fall within your cycle.
At the start of a new cycle (your follicular phase), your LH levels will likely be low. Then as you approach the middle of your cycle (when you’re about to ovulate), they’ll begin to rise. This happens because your estrogen levels will be higher and signal to your pituitary gland that it’s time to produce LH.
Once your ovary has a follicle that’s ready to release a mature egg, your LH will surge. Ovulation occurs about 24 – 36 hours after this initial surge and 8 – 20 hours after the peak.
After ovulation, your LH levels will drop off a bit, but they’ll still be slightly higher than they are in the very beginning of your cycle. This is because luteinizing hormone (LH) supports the corpus luteum (the ruptured follicle) post-ovulation.
Now that you understand the typical LH pattern, let’s talk about other scenarios for LH surges.
Does LH rise before your period?
Yes, it is possible for LH to surge before a period. Let’s dig into a few potential circumstances that could cause this to happen.
Outside of your ovulation window, LH can rise due to:
1. A drop in progesterone levels
In the luteal phase, the corpus luteum takes the lead in producing progesterone. When progesterone levels increase during this time, they keep LH levels relatively low.
If no pregnancy develops, then the corpus luteum will start breaking down. This usually happens when you reach 9-11 days post ovulation (DPO). When the corpus luteum declines, your progesterone levels decrease. In turn, this can cause a very slight surge in LH.
Generally, this temporary increase in LH will be fairly small. Usually not as sharp as your pre-ovulation surge. But depending on your unique cycle and baseline LH levels, you could get false positive results on your urine test.
Know more: 6 Reasons Why Your Ovulation Test Shows False Positive
2. Supporting implantation
Another possibility for an LH surge before period is that you are in early pregnancy. If the egg gets fertilized, your LH levels will jump in to support with implantation.
Here’s what this LH surge looks like in action:
- During implantation, LH will attach to the LH receptors of both the corpus luteum and the endometrium.
- The just-right amount of LH helps the corpus luteum with its job of producing progesterone.
- LH also helps maintain ideal levels of estrogen and progesterone in the uterine lining. (This is where the embryo nestles in to officially begin a pregnancy.)
- Altogether, this means that LH supports endometrial receptivity. (This is a fancy phrase referring to the ideal conditions for successful implantation.)
- A slight rise in LH during this time can also keep the fertilized egg from implanting too soon.
As you can see, pregnancy is made possible with the proper balance of progesterone, estrogen, and LH. LH production during this window allows for higher chances of successful implantation. So it’s a true team effort that is impeccably timed.
3. A cross-reaction with hCG
A third possibility for a pre-menstruation LH surge is the cross-reaction of hormones on the test strip.
Not all ovulation strips are created the same. And this matters when it comes to getting the most accurate LH results.
Here’s a quick run-down of how this cross-reaction is possible:
- LH and the pregnancy hormone, human chorionic gonadotropin (hCG), have similar molecular structures.
- Each hormone has both an alpha subunit and a beta subunit.
- Their alpha subunits are identical, while their beta subunits are slightly different. (Look at the image below to see what we mean)
So why does this all matter?
When you take an LH test that only detects alpha LH, it may mistake hCG for LH. (Remember, their alpha subunits are exactly the same.) If this happens, you’ll see a positive result for LH when in reality, it was your hCG that was detected.
Know more: 6 Reasons Your Ovulation Test Shows False Positive
Can you have an LH surge before your period and still be pregnant?
Yes, it is possible to have an LH surge before your period.
This is because you have a slight LH surge that helps support your endometrium and corpus luteum during implantation.
Can an LH surge before your period prevent you from being pregnant?
No, an LH surge before menstruation doesn’t prevent pregnancy. Remember, LH reacts in response to your other fertility hormones and physiological conditions.
An LH surge that happens before your period could be caused by a drop in progesterone or by your LH working to help the embryo implant. Think of your LH levels as one pixel of the larger fertility picture.
FAQs
There are two reasons this could happen. First, it’s possible that your natural LH levels are on the lower side. A lot of LH tests measure LH levels based on average thresholds. So if you have naturally lower LH levels, even when you have a surge, an LH test may not detect it.
Another possibility is that you may be having a regular period without actually ovulating or having LH surges. When you don’t ovulate consistently, it can cause your uterine lining to become unstable. This can lead to bleeding that is similar to a period (“breakthrough bleeding”).
In the very beginning stages of pregnancy, LH levels are slightly elevated. This is because LH helps support the endometrium and corpus luteum during implantation. But once the placenta takes over producing progesterone around 10 – 12 weeks, LH is no longer needed. At this time, LH levels will drop down.
You likely have either a biphasic surge pattern or multiple LH peaks. This is when you have multiple peaks of LH in the same cycle.
There are actually several different LH surge patterns. These include: single, plateau, biphasic, and multiple. Having more than one LH peak or surge is not unusual and typically nothing to worry about. But it’s helpful to be aware of the various surge patterns so you can better predict ovulation.
A second LH surge prior to your menstrual period could be due to dropping progesterone levels or early pregnancy. It’s also possible you’re not getting accurate results on your ovulation test. There are actually quite a few reasons you could get false positive ovulation tests.
It depends on the length of your menstrual cycle. Ovulation occurs around 12-14 days before the next period. So if you have regular cycles and you want to capture your LH surge, add a few days to that and test around 17 days before your expected period.
Need a concrete example? If your cycle length is usually around 27 days, start LH testing on CD 10. If your cycles are 32 days, start testing around CD15. Of course, you can start testing slightly earlier if you’re concerned about missing your surge or if you have irregular periods.
No, an LH surge only predicts ovulation but doesn’t actually confirm ovulation. Sometimes this is no reason to be concerned. Anovulation can happen occasionally even in healthy, menstruating women. But there are also some conditions like polycystic ovary syndrome (PCOS) that lead to regular anovulation.
Measuring progesterone and its urine metabolite PdG is what actually confirms if you’re ovulating or not. So if you’re struggling to tell if you’re ovulating, a great option is to use an advanced fertility monitor like Inito. Inito not only measures LH, estrogen, and FSH to predict your fertile window, but it also measures PdG to confirm ovulation on a single test strip.
The exact LH level that leads to ovulation differs for each person. A general range for the highest peak of LH is between 21.9 to 56.6 IU/mL. But some women may have LH levels outside this range and still ovulate normally. One study found that urine LH levels could be as low as 6.5 mIU/mL or as high as 101 mIU/mL and still trigger ovulation.
Yes, this is possible, although your chances of conceiving are a little lower. Ovulation usually happens 24 – 36 hours after your LH starts rising. And then once you ovulate, the egg can survive for 24 hours. This means you could conceive 2 days after a positive ovulation test.
But conception just means that the sperm fertilized the egg. The fertilized egg still needs to successfully implant into the uterine lining for pregnancy to be official. And most home pregnancy tests wouldn’t be able to detect hCG until closer to 12-14 DPO when you’re nearing your missed period.
Yes, this can happen. Many ovulation tests test for alpha LH. Since alpha LH is identical to the alpha subunit of hCG, an ovulation test could mistake the alpha LH for hCG. However, this isn’t the most reliable way to test for pregnancy – you’re better off taking a pregnancy test to confirm.
