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Understanding the LH Surge: Your Key to Optimizing Fertility

Zoe Kaplan
Zoe Kaplan

If you can detect or predict your LH surge, you can know when to time intercourse and increase your chances of conception.

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Published:
Feb 10, 2024
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Aug 10, 2025
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If you can detect or predict your LH surge, you can know when to time intercourse and increase your chances of conception.

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If you can detect or predict your LH surge, you can know when to time intercourse and increase your chances of conception.

Are you trying to conceive and having trouble finding your fertile window? Understanding the LH surge, the pivotal event in the reproductive journey, can be the missing piece of the puzzle on your path to parenthood.

The LH surge, or luteinizing hormone surge, signals the prime window of fertility and ovulation. If you can detect or predict the LH surge, you can know when to time intercourse and increase your chances of conception. Whether you're just embarking on your fertility journey or have been diligently trying for a while, here’s everything you need to know about the LH surge and how to take control of your fertility like never before.

What is luteinizing hormone?

First: what is luteinizing hormone (LH)? Luteinizing hormone is a crucial reproductive hormone produced by the anterior pituitary gland, a small gland located at the base of the brain.

LH is an important reproductive hormone because it stimulates the ovaries to produce estrogen and progesterone. 

When luteinizing hormone rapidly increases, it triggers the release of a mature egg from the ovary, also known as ovulation.

After ovulation, LH also helps stimulate the formation of the corpus luteum, a temporary structure in the ovary that produces progesterone to support the early stages of pregnancy.

What is the LH surge?

The LH surge is an important moment in your menstrual cycle that's all about fertility. LH, short for luteinizing hormone, is produced by the pituitary gland—a tiny but mighty gland at the base of your brain. It's like the conductor of an orchestra, calling the shots for your reproductive system, and the LH surge is like the big finale.

When your pituitary gland releases a surge of LH into your bloodstream, it signals to your ovaries to get ready for ovulation. As LH levels skyrocket, it triggers the bursting of the ovarian follicle, releasing that precious egg.

This is the optimal time for fertilization because once that egg meets sperm, it's on its way to potential implantation.

Knowing when the LH surge happens gives you the power to make informed choices and boost your chances of conception.

How long does the LH surge last?

The LH surge typically lasts for about one to two days, or 24 to 48 hours. During the surge, there is a rapid increase of LH levels, which then triggers ovulation. 

Ovulation then occurs about 24 to 36 hours after the onset of the LH surge, and 8-20 hours after the LH peak.

LH surge and fertility

The LH surge and fertility are correlated because the LH surge triggers ovulation—and ovulation is the key to figuring out your fertile window. Once you know your fertile window, you and your partner can time your intercourse optimally and increase your chances of conception.

The LH surge is also a great measure of fertility because it can help people who have irregular cycles. Instead of estimating when you’re ovulating based on the day of your cycle, the LH surge provides a clear picture so you never have to guess.

Finally, the LH surge can help you monitor your hormone health, which can affect your fertility. The presence and timing of the LH surge provide insights into the overall health of the reproductive system. Consistent and predictable LH surges are indicators of a healthy ovulation process. On the other hand, irregular or absent LH surges may signify underlying hormonal imbalances that can affect fertility. Tracking the LH surge can help collect data on your hormone fluctuations.

>>RELATED: 8 Signs Your Hormones May Be Out of Balance – And What to Do Next.

Understanding the significance of the LH surge empowers people with knowledge about their ovulation so they can take an active role in timing their attempts to conceive. By tracking and interpreting the LH surge, couples can make informed decisions and increase their chances of achieving their desired goal of pregnancy.

How long after an LH surge are you fertile?

Generally, after the LH surge, ovulation typically takes place within the next 24 to 36 hours. This means that the window of optimal fertility typically extends for about two to three days after the surge.

It's worth noting that every menstrual cycle can vary, and the length of the fertile window may also differ. Factors such as hormone levels, overall health, and individual variations can influence the precise timing. Therefore, it's advisable to track your menstrual cycle, monitor LH surges consistently, and consult with a healthcare professional for personalized guidance.

When to have sex after the LH surge

If you’re trying to conceive, you’ll need to have sex during the fertile window, or two to three days after the LH surge, so the sperm can fertilize the egg that was released during ovulation. 

Keep in mind that sperm can survive inside the female body for up to five days, so having intercourse in the days leading up to and after the LH surge can extend your fertile window and increase your chances of conception.

>>MORE: When Am I the Most Fertile?

Does an LH surge always mean ovulation?

While an LH surge is a reliable indicator of ovulation—and therefore your fertile window—it's important to note that an LH surge does not guarantee ovulation in every instance. While uncommon, there can be cases where an LH surge occurs without subsequent ovulation. When does this happen?

  • Hormonal imbalances: Hormonal imbalances, such as polycystic ovary syndrome (PCOS), can disrupt the normal ovulation process even in the presence of an LH surge.
  • Stress and emotional factors: High levels of stress, emotional turmoil, or significant life events can interfere with ovulation, despite the occurrence of an LH surge.
  • Medications and medical conditions: Certain medications, such as certain types of birth control, and certain medical conditions, such as thyroid disorders, can affect ovulation even if an LH surge is detected. However, it depends on the person—some individuals with thyroid disorders may still ovulate regularly, while others may experience irregular or absent ovulation.
  • Perimenopause or menopause: During the transition to menopause (perimenopause) and in menopause itself, the hormonal fluctuations can lead to irregular ovulation or the absence of ovulation despite an LH surge.

If you have concerns about ovulation or are experiencing irregularities in your cycle, it's recommended to consult with a healthcare professional for a thorough evaluation.

How to detect your LH surge

Detecting your LH surge is crucial for determining your most fertile days. So, how can you do it?

LH surge symptoms

Unfortunately, the LH surge typically doesn’t cause many noticeable physical symptoms in most people. However, some people might experience mild symptoms. Because the LH surge comes right before ovulation, many signs of ovulation and LH surge symptoms are similar. Keep in mind these symptoms may vary from one person to the next, and an absence of symptoms doesn’t mean you’re not going through an LH surge.

Some potential LH surge symptoms include:

  • Increased basal body temperature: After the LH surge, your basal body temperature, or your temperature when your body is fully at rest, may rise slightly. To track BBT, you need to be very consistent in recording temperature to ensure you detect changes accurately. 
  • Changes in cervical mucus: Around the time of ovulation and the LH surge, cervical mucus might become clearer, more abundant, and stretchy, resembling raw egg whites. This change in cervical mucus consistency can be a sign of increased fertility.
  • Mild abdominal discomfort: Some women may experience mild abdominal discomfort or sensations, often described as a dull ache or twinge, around the time of ovulation and the LH surge. This discomfort is known as mittelschmerz and is thought to result from the release of the egg from the ovary.
  • Increased Libido: Hormonal changes associated with ovulation, including the LH surge, can lead to an increase in sexual desire or libido for some women.

Tracking your hormones

While some people might experience mild symptoms around the LH surge, the best way to determine your LH surge is to use a tool that specifically measures the LH in your body.

Oova is a fertility tracking device that offers a comprehensive approach to monitoring hormone levels, including the LH surge. It consists of a handheld reader and disposable test strips. Users collect urine samples on the test strips, which are then inserted into the reader for analysis.

Oova provides quantitative measurements of LH levels and offers a more in-depth understanding of your hormonal patterns, helping you track your fertility more precisely. Oova’s quick results can also help predict the LH surge in advance, allowing you to plan intercourse accordingly.

LH surge range

If you’re detecting your LH surge, what range should you expect? The typical range of an LH surge can vary between 25-40 international units per liter (IU/L). This surge is considered the normal range and indicates a healthy ovulation process.

However, the LH surge is not a one-size-fits-all phenomenon. The intensity of the surge can vary from person to person and even from cycle to cycle within the same person. When interpreting LH surge levels, it’s crucial to take into account an individual's baseline and their specific fertility patterns.

What’s considered a low number in an LH surge?

A low LH surge refers to levels below the expected range, so below 25 IU/L. It could indicate an issue with the timing or quality of ovulation. In some cases, a consistently low LH surge may be associated with conditions such as hypothalamic dysfunction or low ovarian reserve.

What’s considered a high number in an LH surge?

A high LH surge refers to levels above the typical range, around 44.6 IU/L. This may indicate conditions such as PCOS, where the body produces excess LH, or it can be a response to certain medications. A consistently high LH surge without ovulation could affect fertility and may require medical attention.

>>RELATED: How Is Polycystic Ovary Syndrome (PCOS) Diagnosed?

It's important to note that interpreting LH surge levels should be done in conjunction with other fertility signs and under the guidance of a healthcare professional. Monitoring the trends in your LH surge levels over multiple cycles can provide a clearer picture of your individual patterns and help in optimizing your fertility journey.

Takeaway

Understanding and tracking the LH surge is a key part of arming you with the right information to track and predict ovulation. The LH surge acts as a vital signpost in a woman's menstrual cycle, indicating the likely time of ovulation and optimal time for fertilization. Using fertility tracking devices like Oova can provide accurate and detailed measurements of LH levels, empowering individuals with valuable insights into their fertility patterns.

Remember, the journey to parenthood may have its ups and downs, but understanding the role of the LH surge and utilizing tools like Oova can provide invaluable support on the path to achieving your dreams of starting or expanding your family.

About the author

Zoe Kaplan
Zoe Kaplan is a writer and content strategist passionate about creating content that helps people navigate the world a little more easily. Zoe has worked across verticals, from women's career development to reproductive health. You can check out more of her work at zoeakaplan.com.

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https://www.oova.life/blog/progesterone-supplementation-guide
Can I take progesterone if I'm breastfeeding?
Yes, progesterone is generally safe while breastfeeding and doesn't significantly affect milk supply. However, always discuss with your healthcare provider before starting any hormone supplementation while nursing.
https://www.oova.life/blog/progesterone-supplementation-guide
Is it safe to take progesterone throughout pregnancy?
Yes, when prescribed by your healthcare provider. Progesterone supplementation in early pregnancy is safe and can reduce miscarriage risk in women with low progesterone or a history of pregnancy loss. Most providers continue supplementation through the first trimester (weeks 10-12) when the placenta takes over.
https://www.oova.life/blog/progesterone-supplementation-guide
Can progesterone supplementation cause weight gain?
Progesterone can cause temporary water retention and bloating, which may show up as a few pounds on the scale, but it doesn't cause true fat weight gain. Most women don't experience significant weight changes from progesterone supplementation.
https://www.oova.life/blog/progesterone-supplementation-guide
Can I switch from pills to suppositories or vice versa?
Yes, but only under your doctor's guidance. The dosing and timing may need adjustment when switching between forms since they're absorbed differently. Never switch on your own, especially if you're pregnant or undergoing fertility treatment.
https://www.oova.life/blog/progesterone-supplementation-guide
Will progesterone supplementation delay my period?
Yes, progesterone keeps the uterine lining intact, so if you're not pregnant and continue taking progesterone, your period will be delayed. Once you stop taking it, your period should start within 2-10 days. If you are pregnant, progesterone helps maintain the pregnancy and you won't get a period.
https://www.oova.life/blog/progesterone-supplementation-guide
Should I take progesterone pills orally or vaginally?
For fertility and pregnancy support, vaginal progesterone is usually preferred because it delivers higher concentrations directly to the uterus. For perimenopause or general hormone balance, oral progesterone often works well and is more convenient. Your doctor will recommend the best route based on your specific needs.
https://www.oova.life/blog/progesterone-supplementation-guide
When should I start taking progesterone after ovulation?
Typically, progesterone supplementation for luteal phase support starts 2-3 days after ovulation (confirmed by LH surge or temperature rise). Your doctor will give you specific timing based on your protocol. Some women start immediately after a positive ovulation test.
https://www.oova.life/blog/progesterone-supplementation-guide
What's better: progesterone cream or pills?
Pills (oral micronized progesterone) are generally more effective and reliable than creams because absorption from creams is inconsistent. For medical conditions like fertility issues, low progesterone, or HRT, prescription pills or suppositories are strongly recommended over over-the-counter creams.
https://www.oova.life/blog/low-vs-high-progesterone-symptoms
How can I tell if I have low or high progesterone?
The only definitive way to know is through hormone testing via blood tests or at-home urine tests that measure progesterone metabolites. However, symptom patterns can provide clues: anxiety and irregular periods suggest low progesterone, while bloating and extreme fatigue suggest high progesterone.
https://www.oova.life/blog/low-vs-high-progesterone-symptoms
When during my cycle should I test progesterone levels?
Test progesterone levels during the luteal phase, typically 7 days after ovulation or around day 21 of a 28-day cycle. This is when progesterone should be at its peak, making it easier to identify if levels are too low or too high.
https://www.oova.life/blog/low-vs-high-progesterone-symptoms
What are the main differences between low and high progesterone symptoms?
Low progesterone typically causes irregular or heavy periods, anxiety, hot flashes, and sleep issues. High progesterone causes bloating, fatigue, intense breast tenderness, and depression-like mood changes. Low progesterone symptoms persist throughout your cycle, while high progesterone symptoms are most intense during the luteal phase.
https://www.oova.life/blog/low-vs-high-progesterone-symptoms
Can you have symptoms of both low and high progesterone?
Some symptoms like breast tenderness and mood changes can occur with both low and high progesterone, making it confusing. However, the timing, intensity, and accompanying symptoms differ. Hormone testing is the best way to determine which imbalance you're experiencing.
https://www.oova.life/blog/10-dpo
Can stress affect 10 DPO symptoms?
Yes, stress can worsen or mimic 10 DPO symptoms. Stress increases cortisol, which can cause cramping, fatigue, and mood changes similar to both PMS and early pregnancy. During the two-week wait, try stress-reduction techniques like gentle exercise, meditation, or spending time with loved ones.
https://www.oova.life/blog/10-dpo
Is it better to test at 10 DPO or wait?
It's better to wait until 12–14 DPO for more accurate results. Testing at 10 DPO often leads to false negatives because hCG levels may still be too low. If you absolutely can't wait, use a sensitive early detection test with first morning urine, and be prepared to retest in 2–3 days if negative.
https://www.oova.life/blog/10-dpo
What does implantation bleeding look like at 10 DPO?
Implantation bleeding at 10 DPO is typically light pink or brown, much lighter than a period, and lasts 1–2 days. It's often just spotting when you wipe or a few drops on a panty liner. However, only 15–20% of pregnant women experience implantation bleeding—most don't have any bleeding at all.
https://www.oova.life/blog/10-dpo
Why am I cramping at 10 DPO?
Cramping at 10 DPO can be caused by elevated progesterone (whether you're pregnant or not), implantation (if you're pregnant), or premenstrual cramping. Unfortunately, cramping alone can't tell you if you're pregnant since progesterone causes similar symptoms in both scenarios.
https://www.oova.life/blog/10-dpo
What are the chances of a BFP at 10 DPO?
If you're pregnant, you have about a 50–60% chance of getting a positive test at 10 DPO. This means there's a 40–50% chance of a false negative even if you conceived. Chances improve significantly by 12–14 DPO.
https://www.oova.life/blog/10-dpo
What DPO is most accurate for pregnancy testing?
14 DPO (the day of your missed period) is the most accurate time to test, with 99% accuracy. 12 DPO offers 80–90% accuracy. 10 DPO has only 50–60% accuracy. For best results, wait as long as you can—ideally until 12–14 DPO.
https://www.oova.life/blog/10-dpo
Is 10 DPO too early to test?
10 DPO is considered early for pregnancy testing. While some women get positives at 10 DPO, accuracy is only 50–60% if you're pregnant. For best results, wait until 12 DPO (80–90% accuracy) or 14 DPO/missed period (99% accuracy).
https://www.oova.life/blog/10-dpo
Can you have implantation at 10 DPO?
Yes, implantation can still occur at 10 DPO, though 84% of women have already implanted by this point. Late implantation at 10–12 DPO is normal. If implantation happens at 10 DPO, you won't get a positive pregnancy test for another 2–3 days.
https://www.oova.life/blog/10-dpo
What does a negative test at 10 DPO mean?
A negative test at 10 DPO does not mean you're not pregnant. It's very common to get negatives at 10 DPO even if you conceived. Your hCG levels may still be too low, or implantation may have occurred later. Wait until 12–14 DPO to retest for more accurate results.
https://www.oova.life/blog/10-dpo
Can you get a positive pregnancy test at 10 DPO?
Yes, but only about 50–60% of pregnant women will get a positive at 10 DPO. The other 40–50% have hCG levels that are still too low to detect. If you test negative at 10 DPO, wait 2–3 days and test again.
https://www.oova.life/blog/high-progesterone-symptoms
Can high progesterone cause weight gain?
Yes, elevated progesterone can cause temporary weight gain through water retention and bloating. This is a normal part of the luteal phase and early pregnancy.
https://www.oova.life/blog/how-to-increase-estrogen
Does stress affect estrogen levels?
Yes, chronic stress elevates cortisol, which can suppress estrogen production and disrupt hormonal balance. Stress reduction through meditation, yoga, adequate sleep, and self-care practices helps maintain optimal estrogen levels.
https://www.oova.life/blog/how-to-increase-estrogen
When should I consider medical treatment for low estrogen?
Consider medical intervention if natural methods don't improve symptoms after 3 months, if symptoms severely impact quality of life, if you're experiencing early menopause (before 40), or if you have fertility concerns. Hormone replacement therapy may be appropriate in these cases.
https://www.oova.life/blog/how-to-increase-estrogen
What are the signs that my estrogen is increasing?
Signs of rising estrogen include more regular menstrual cycles, reduced hot flashes, improved vaginal lubrication, better mood stability, increased energy, and improved skin elasticity. You may also notice reduced symptoms that originally indicated low estrogen.
https://www.oova.life/blog/how-to-increase-estrogen
Can exercise increase estrogen levels?
Yes, moderate exercise stimulates estrogen release and helps maintain hormonal balance. Aim for 150 minutes of moderate cardio weekly plus strength training twice per week. However, excessive exercise can actually lower estrogen, so balance is key.
https://www.oova.life/blog/how-to-increase-estrogen
How long does it take to increase estrogen naturally?
With consistent dietary and lifestyle changes, you may notice improvements in symptoms within 4-8 weeks. However, significant hormonal changes typically take 2-3 months. Tracking your cycle and symptoms can help you monitor progress.
https://www.oova.life/blog/how-to-increase-estrogen
What foods increase estrogen levels naturally?
Foods high in phytoestrogens can help increase estrogen naturally. The best options include flax seeds (high in lignans), soy products (tofu, tempeh, edamame), lentils, chickpeas, whole grains (oats, quinoa, brown rice), and garlic. These plant compounds mimic estrogen's effects in the body.
https://www.oova.life/blog/perimenopause
What helps relieve hot flashes quickly?
Cool environments, layered clothing, herbal teas, and medical treatments like gabapentin or HRT may help—depending on severity. Lifestyle changes like reducing caffeine and alcohol can also provide relief.
https://www.oova.life/blog/perimenopause
Are there tests to confirm perimenopause?
Yes. Tests measuring estradiol, LH, and FSH levels can indicate hormonal shifts—but diagnosis is often symptom-based since hormone levels fluctuate widely during perimenopause.
https://www.oova.life/blog/perimenopause
How do I know it's perimenopause and not something else?
A doctor may recommend hormone testing (like LH, E3G, and PdG) and track symptom timing. Diagnosis is often based on symptoms combined with age and menstrual pattern changes.
https://www.oova.life/blog/perimenopause
What's the earliest age perimenopause can start?
Some women begin experiencing symptoms as early as their mid-30s, though perimenopause typically starts between ages 38-45.
https://www.oova.life/blog/perimenopause
Does perimenopause affect mental clarity?
Yes. Brain fog and difficulty concentrating are common during hormone fluctuations in perimenopause.
https://www.oova.life/blog/TBD-10-symptoms-and-how-to-get-relief
What happens after the last sign of perimenopause?
After your final period, you enter postmenopause. You'll need 12 consecutive months without a period to confirm menopause. Many symptoms gradually improve, though some like vaginal dryness may persist without treatment.
https://www.oova.life/blog/TBD-10-symptoms-and-how-to-get-relief
When do perimenopause symptoms finally stop?
Some symptoms like brain fog improve after menopause, while others like hot flashes may continue for up to 10 years post-menopause. Vaginal symptoms often persist or worsen without treatment. Each person's timeline is different.
https://www.oova.life/blog/high-progesterone-symptoms
Is high progesterone a sign of pregnancy?
Yes, high progesterone is one of the earliest indicators of pregnancy. Progesterone levels rise significantly after conception to support the developing embryo and reach their peak during the third trimester.
https://www.oova.life/blog/TBD-10-symptoms-and-how-to-get-relief
Can you still get pregnant in late perimenopause?
Yes, you can still get pregnant during perimenopause as long as you're having periods, even if they're infrequent. Continue using birth control until you've gone 12 consecutive months without a period and have officially reached menopause.
https://www.oova.life/blog/TBD-10-symptoms-and-how-to-get-relief
Do symptoms get worse before perimenopause ends?
Yes, most perimenopause symptoms intensify in the final 1-2 years before menopause. Hot flashes peak around your final period, vaginal symptoms worsen, and mood changes increase. However, brain fog typically improves in late perimenopause.
https://www.oova.life/blog/TBD-10-symptoms-and-how-to-get-relief
How long does late perimenopause last?
Late perimenopause typically lasts 1-3 years before your final period. However, the exact duration varies significantly from person to person. You've reached menopause after 12 consecutive months without a period.
https://www.oova.life/blog/high-progesterone-symptoms
What are the symptoms of high progesterone?
High progesterone symptoms include fatigue, bloating, breast tenderness, weight gain, anxiety, depression, headaches, and food cravings. During pregnancy, you may also experience increased nipple sensitivity and muscle aches.
https://www.oova.life/blog/TBD-10-symptoms-and-how-to-get-relief
What are the first signs that perimenopause is ending?
The earliest signs include longer gaps between periods (60+ days), intensifying hot flashes that peak around your final period, and worsening vaginal dryness. These symptoms typically increase in late perimenopause before you reach official menopause.
https://www.oova.life/blog/high-progesterone-symptoms
When should I be concerned about high progesterone?
Consult a healthcare provider if you experience high progesterone symptoms outside your luteal phase when not pregnant, or if symptoms include severe pelvic pain, abnormal vaginal bleeding, or rapid weight gain while on hormone therapy.
https://www.oova.life/blog/high-progesterone-symptoms
How do you test progesterone levels?
Progesterone can be measured through blood tests at your doctor's office or at-home urine tests that measure PdG (a progesterone metabolite). Testing is typically done during the luteal phase, about 7 days after ovulation.

About the Oova Blog:
‍Our content is developed with a commitment to high editorial standards and reliability. We prioritize referencing reputable sources and sharing where our insights come from. The Oova Blog is intended for informational purposes only and is never a substitute for professional medical advice. Always consult a healthcare provider before making any health decisions.

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