Trying to conceive and seeing the term LH on your ovulation test kit? Or did your doctor mention your LH hormone levels, and now you are unsure what it means? LH, i.e., Luteinising hormone, is one of the most important fertility hormones in women. It is the hormone responsible for ovulation, meaning it triggers the ovary to release an egg. Without a proper LH surge, ovulation cannot occur naturally.
In this guide, you will learn what LH is, how it works, what normal LH levels look like, and how LH testing can help you time ovulation accurately.
What is luteinising hormone?
Luteinising hormone (LH) is a reproductive hormone made by the pituitary gland, a small gland located at the base of the brain.
It plays a key role in both female and male reproductive health. In women, it is the hormone responsible for ovulation.
What does LH do in women?
LH and ovulation
LH works closely with another hormone called FSH (follicle stimulating hormone). Together, they regulate the menstrual cycle.
Mid-cycle, LH rises sharply. This rise is called the LH surge. The surge triggers the ovary to release a mature egg. Ovulation usually happens 24-36 hours after the LH surge. This short window is the most fertile time in the cycle.
LH and progesterone production
After ovulation, LH helps support the corpus luteum, a structure in the ovary that produces progesterone. Progesterone is a hormone that prepares the uterus for pregnancy.
LH levels during the menstrual cycle
LH hormone levels change throughout the cycle.
| Cycle Phase | LH Activity |
| Follicular phase | Low to moderate LH |
| Ovulation phase | Sharp LH surge |
| Luteal phase | LH decreases |
These changes help regulate the timing of egg release.
What does LH do in men?
LH and testosterone
In men, luteinising hormone stimulates the testes to produce testosterone.
LH’s role in sperm production
Testosterone supports sperm production. Therefore, LH indirectly plays a role in male fertility.
The LH surge and how OPKs detect it
The LH surge is a quick rise in luteinizing hormone. This rise tells your body that ovulation is about to happen. It usually occurs around the middle of your menstrual cycle, but the exact day can be different for each person. Ovulation normally happens about 24 to 36 hours after the LH surge begins.
Ovulation predictor kits, also called OPKs, check the level of LH in your urine. When LH rises to surge levels, usually around 25 to 75 mIU per mL or higher, the test shows a positive result. A positive OPK means your most fertile days are here, and this is the best time to try to get pregnant.
Why this matters for the fertile window
A positive OPK test signals that ovulation is likely imminent, helping identify the most fertile days of the cycle. Since the egg survives about 12 to 24 hours after release and sperm can survive up to 5 days, timing intercourse in the 1 to 2 days following a positive test significantly increases pregnancy chances.
Tracking LH trends across cycles also helps distinguish between a true surge and fluctuating baseline LH levels, especially in individuals with irregular cycles.
What are normal LH levels in women?
Normal LH levels by phase
Approximate reference ranges (may vary by lab):
| Phase | Normal LH Levels in Women |
| Follicular phase | 1.9 – 12.5 IU/L |
| Ovulation peak | 8.7 – 76.3 IU/L |
| Luteal phase | 0.5 – 16.9 IU/L |
Levels vary by age and individual factors.
Normal LH levels in men
Typical adult male range: 1.8 – 8.6 IU/L.
What does high LH mean?
High LH hormone levels may be seen in:
- PCOS
- Perimenopause
- Primary ovarian insufficiency
In PCOS, LH may remain elevated, which can interfere with regular ovulation.
What does low LH mean?
Low LH levels may occur with:
- Hypothalamic amenorrhea
- Pituitary disorders
- Chronic stress
- Underweight or excessive exercise
When should you take an LH test?
Best time to test
For urine LH tests:
- start testing about 7 days before your expected ovulation date. If you are new to LH testing or unsure about your cycle pattern, begin testing right after your period ends and continue daily until you see a clear LH peak followed by a drop on your chart.
- test between late morning and evening ( between 10AM to 8PM)
- avoid excessive fluid intake before testing
How LH kits help you get pregnant
LH test strips help identify the fertile window by detecting the LH surge.
Benefits include:
- Accurate ovulation timing
- Better understanding of hormone patterns
- Improved intercourse timing
Final thoughts
Understanding what LH is and how it functions can help you better interpret ovulation tests and hormone reports. LH plays a central role in fertility by triggering egg release and supporting the luteal phase.
If you are trying to conceive, tracking your LH surge can help you identify your most fertile window.
You can use easy@home LH test kits along with the Premom app to monitor your hormone patterns and better understand your ovulation timing.
If you are new to LH tracking or unsure how to read your results, you can connect with our experts through the Ask an Expert (AAE) feature inside the Premom app. Our team is here to guide you step by step and help you feel confident in using LH testing as part of your fertility journey.
FAQs – LH test with ovulation test kit
LH is a luteinising hormone produced by the pituitary gland. Its main function in women is to trigger ovulation and support progesterone production.
Normal LH levels vary by cycle phase. They are lower in the follicular phase, peak during ovulation, and decrease in the luteal phase.
Low LH may prevent ovulation, which can lead to irregular or missed periods.
High LH may be associated with PCOS, perimenopause, or ovarian function changes.
Luteinising hormone (LH) is the hormone that induces ovulation.
Ovulation usually occurs 24 to 36 hours after the LH surge.
Disclaimer: This content is for educational purposes only and is not medical advice. Please consult a healthcare professional for personalised guidance.
References
- Centers for Disease Control and Prevention. About the menstrual cycle.
https://www.cdc.gov/ncbddd/menstrualcycle/index.html - National Library of Medicine. Luteinizing Hormone (LH) blood test.
https://medlineplus.gov/lab-tests/luteinizing-hormone-lh-blood-test/ - World Health Organization. Sexual and reproductive health.
https://www.who.int/health-topics/sexual-health - American College of Obstetricians and Gynecologists. Ovulation.
- https://www.acog.org/womens-health
