LH Surge & Ovulation Tests – How to Determine Your LH Level and Fertile Days

Planning a pregnancy, using ovulation tests, or keen to understand what your hormone levels reveal about your cycle? Your LH level (luteinising hormone) is the most reliable marker of peak fertility. In this article, you'll learn how the LH surge works, when it occurs, and how to use modern tests and apps to optimise timing and boost your chances of conceiving.

The Female Cycle – Four Phases, One Aim

Each cycle comprises four precisely co-ordinated phases:

• Menstruation: Shedding of the uterine lining.
• Follicular Phase: FSH stimulates the maturation of multiple follicles; one dominant follicle emerges.
• Ovulation (Egg Release): A sharp LH surge (LH peak) ruptures the follicular wall – the egg is released.
• Luteal Phase: The corpus luteum produces progesterone to prepare the endometrium for potential implantation.

Hormones as Conductors – Focus on LH

Endotext – The Normal Menstrual Cycle demonstrates how precisely oestrogen, progesterone, FSH and LH work together. Once the dominant follicle reaches optimal size, the LH peak reliably triggers egg release.

• Oestrogen & Progesterone: Build up and maintain the uterine lining.
• FSH: Stimulates follicle growth.
• LH: The starting pistol for ovulation – its peak is the most accurate indicator of peak fertility.

The LH Surge – What Happens and When?

Biochemistry in Brief

Around 35–44 hours before ovulation, your LH level begins to rise. It reaches its maximum around 10–12 hours before the egg is released and stays elevated for approximately 12–24 hours. During this window, the follicle ruptures and the egg travels into the fallopian tube.

Timing Is Everything

• Sperm can survive ≈ 5 days.
• The egg remains viable ≈ 12–18 hours.
• Intercourse before the LH peak increases the chance that sperm are ready when the egg is released.

Recognising Body Signals – Your Natural Fertility Radar

In addition to the LH surge, your body gives other clues:

• Ovulation Pain (Mittelschmerz): A twinge in the lower abdomen when the follicle ruptures.
• Cervical Mucus: Clear, stretchy and slippery (see our cervical mucus guide).
• Basal Body Temperature: Rises by about 0.3 °C shortly after ovulation.
• Increased Libido: Many women experience a spike in sexual desire around ovulation.

Ovulation Tests – Measuring Your LH Level Accurately

How They Work

Urine-based ovulation tests use an immunological response: once your LH level crosses a threshold, a test line appears. A prospective PubMed study (N = 107 cycles) showed a 96 % detection rate when testing daily at the same time.

Practical Tips

• Consistent Testing Time: Test between 10 am and 8 pm when LH is most stable in urine.
• Adequate Hydration: Do not dilute or concentrate your urine artificially.
• Digital Tests: A smiley display prevents misreading faint lines.

Cycle Monitoring – Combining Methods Smartly

• Basal Body Temperature Tracking: Confirms ovulation retrospectively.
• Cervical Mucus Observation: Free and immediate feedback.
• Apps & Wearables: Automate measurements and remind you of testing windows – sync data for reliable analysis.

Fertility Treatment – Using LH Strategically

In fertility centres, the LH peak is closely monitored to time treatments such as IVF (in vitro fertilisation) or ICSI (intracytoplasmic sperm injection) for optimal outcomes.

1. Ovarian Stimulation: Multiple follicles mature under FSH injections.
2. Antagonist Protocol: GnRH antagonists prevent a premature LH surge.
3. hCG Trigger: Mimics the natural LH peak once follicles reach ideal size and oestrogen levels.
4. Egg Retrieval: 34–36 hours after the trigger, eggs are collected before follicles rupture.
5. Luteal Support: Progesterone gel or tablets stabilise the endometrium.

Even in a Frozen Embryo Transfer (FET), LH is tracked to schedule the transfer when the endometrium is perfectly prepared – improving implantation and pregnancy rates.

Sperm Donation & Co-Parenting with RattleStork – A Flexible Option

If, despite careful cycle monitoring, conception doesn’t occur, RattleStork offers a practical alternative: our platform connects intended parents with verified donors, allowing couples and individuals to plan home inseminations or co-parenting arrangements independently, safely and affordably.

Conclusion

Your LH level is the most accurate marker for optimal fertility. Combine ovulation tests, body signals and smart apps to make the most of your fertile window. Modern fertility medicine can help with irregularities – and if pregnancy remains out of reach, RattleStork provides a pathway to sperm donation or co-parenting. Stay empowered on your family-building journey.