LH, or luteinising hormone, helps time ovulation and supports a healthy menstrual cycle. Your brain releases LH from the anterior pituitary gland. A sharp rise in LH signals the ovary to release an egg and then supports the corpus luteum, which makes progesterone in the second half of the cycle. If you are trying to conceive, tracking LH can help you find your fertile window and plan intercourse. Serial testing gives a clearer picture than a single result, especially if your cycle length varies. This guide explains what LH does, why levels rise and fall, how to test at home and in clinics, and what low or high results may mean in the Australian healthcare setting. You will also find practical ways to manage timing, lifestyle, and when to speak with a GP or fertility specialist.
Quick Answers About Luteinising Hormone (LH)
What does LH do in the menstrual cycle?
LH triggers ovulation and then supports the corpus luteum, which produces progesterone to prepare the uterine lining for implantation.
When is the LH surge and how long after do you ovulate?
Most people see a surge in the mid cycle. Ovulation usually occurs about 24 to 36 hours after the strongest positive result on an LH test.
Can I rely on one LH test?
No. Daily testing around your expected fertile window is more reliable. Serial tracking shows the rise, peak, and fall, which helps confirm timing.
What luteinising hormone is and why it matters when trying to conceive
Luteinising hormone is one of the main fertility hormones made by the anterior pituitary gland. In the first half of the cycle, LH helps the ovaries make estradiol, a form of oestrogen that thickens the uterine lining. A rapid rise in LH then triggers ovulation, which is the release of a mature egg. After ovulation, LH continues to act on the corpus luteum, the temporary gland left after the egg is released, to support progesterone production. Progesterone stabilises the lining to help an early pregnancy implant.
Because LH rises just before ovulation, it is often used as a marker of the fertile window. Home ovulation tests detect LH in urine. A positive result means the LH surge is underway and that ovulation is likely within the next one to two days. If cycles are irregular or you have a condition that affects ovulation, tracking LH alongside cycle dates, cervical mucus, and basal body temperature can build a fuller picture.
Why LH levels vary and what can cause low or high results
LH is naturally low in the early follicular phase, then it surges to trigger ovulation, and returns to baseline after the peak. Outside this pattern, persistently low LH can occur with hypothalamic suppression. Common reasons include low energy intake, heavy exercise without adequate recovery, high stress, or a low body mass index. Some medicines, including hormonal contraception, also suppress LH. In these settings, ovulation may be delayed or absent until the underlying factor changes.
Higher LH outside the surge window can point to a hormonal imbalance. In some people with polycystic ovary syndrome, the LH to FSH pattern may be altered. High prolactin, thyroid disorders, and premature ovarian insufficiency can also affect LH. A single number rarely tells the full story. Your GP may look at LH together with FSH, estradiol, progesterone, prolactin, thyroid function, and your cycle history. If results sit outside the expected pattern more than once, further assessment helps to find the cause and guide care.
How LH testing works in Australia
There are two main ways to assess LH. The first is home urine testing, which looks for the rise in LH that precedes ovulation. Many Australians use these kits because they are simple and give real time feedback. The second is blood testing organised by a GP, which measures exact LH levels. Blood tests can be useful if cycles are very irregular, if no surge is detected on urine tests, or if a doctor is checking for a hormone disorder.
For most people, serial testing gives better information than a single snapshot. With urine testing, start a few days before you expect to ovulate based on your recent cycle lengths. Test once a day at first, then twice a day when the test line begins to darken. With blood testing, a GP may order a set of tests across the cycle to track the rise and fall of LH and related hormones. This can help confirm ovulation and the timing of the luteal phase.
What LH tests involve at home and in clinics
At home, read the instructions for your specific kit and use the same brand for the whole cycle to avoid variation. Many people prefer testing in the late morning or afternoon because LH can rise during the day. If the instructions suggest first morning urine, follow that advice for consistency. Reduce fluid intake for two hours before testing to avoid diluting the sample. Record results with photos and times so you can see the pattern build over several days. Apps can help chart your surge and predict the next cycle’s window.
In clinic, your GP may request a blood test for LH, FSH, estradiol, prolactin, and thyroid function. If you have irregular cycles or amenorrhoea, tests may be done at any time, then repeated. If you have regular cycles, some doctors test in the early follicular phase for baseline levels, then around mid cycle or after suspected ovulation. The lab report will show a reference range, though ranges differ between labs and depend on where you are in your cycle. Your doctor interprets results alongside symptoms and timing.
Home management to support healthy LH patterns
Regular sleep, balanced nutrition, and moderate exercise support the hypothalamic pituitary ovarian axis. If you have missed periods related to under eating or high training load, a gradual return to adequate energy intake and a review of training can help restore LH pulsatility. Managing stress with simple daily practices like breathing exercises, stretching, or short guided meditation can reduce cortisol, which may help hormone rhythm. Mind body therapies such as meditation and guided imagery are safe to combine with standard care. Track your cycle and LH for three to six months to look for a consistent pattern.
Some supplements are often used during preconception. Myo inositol may support ovarian function and insulin sensitivity in people with polycystic ovary syndrome. Coenzyme Q10 supports cellular energy and may help egg quality. Folic acid is a core preconception nutrient that reduces the risk of neural tube defects. A prenatal multivitamin can make daily dosing easier. Discuss supplements with your GP, especially if you take other medicines or have a medical condition. Avoid promises that a supplement will raise LH on its own. The goal is steady cycles and timely ovulation rather than pushing LH higher than your body needs.
Homeopathy uses highly diluted substances. There is no good evidence that it changes LH or ovulation, so it should not replace medical care. If you choose to use it, consider it as a comfort measure while following medical advice.
Medical options that involve or affect LH
Some people need medical treatment to induce or time ovulation. Gonadotropin therapy uses medicines that contain FSH and sometimes LH to stimulate follicle growth. Human chorionic gonadotropin injections can act like an LH surge to trigger ovulation at a known time. These medicines can increase the chance of ovulation when natural LH signals are not strong or regular. Treatment plans are tailored by a fertility specialist who monitors follicle growth with ultrasound and blood tests. Side effects can include bloating, mood changes, and discomfort at injection sites. Ovarian hyperstimulation is uncommon with careful monitoring but requires prompt care if it occurs.
Oestrogen therapy may be used to regulate cycles in some settings and to build the uterine lining if it is thin. Benefits include more regular bleeding and a receptive lining for implantation. Side effects can include breast tenderness, fluid retention, and nausea. There is a small risk of blood clots in some people. Your doctor will assess personal risk factors such as migraine with aura, smoking, and family history before prescribing.
Supplements marketed for fertility, including blends with myo inositol, folic acid, and CoQ10, are widely available. These nutrients support general reproductive health. They are not a substitute for medical evaluation if ovulation is irregular or absent. A GP or fertility specialist can advise on dose, timing, and whether a product suits your health history.
When to see a GP or specialist in Australia
Book a GP visit if you have cycles longer than 35 days, cycles that vary by more than a week from month to month, very short cycles, or no bleeding for three months when not on hormonal contraception. Also see your doctor if your LH tests never show a clear surge after three months of tracking or if you have signs of a hormone disorder such as excess hair growth, acne that is hard to control, galactorrhoea, or hot flushes at a young age. If you are under 35 and have tried to conceive for a year without success, or over 35 and have tried for six months, ask for a fertility workup. Your GP can order first line tests and refer to a RANZCOG fertility specialist if needed.
Urgent care is needed for severe pelvic pain, heavy bleeding with dizziness, or signs of ovarian hyperstimulation during fertility treatment such as rapid weight gain, severe bloating, or shortness of breath. Healthdirect provides advice on when to seek urgent help, and state health services can guide you to local clinics.
How ovulation and pregnancy tests fit into your plan
Ovulation tests detect LH in urine to help you target intercourse in the fertile window. They work best with consistent timing and daily records. For some people, especially those with polycystic ovary syndrome, tests can show multiple rises. Pairing test results with cervical mucus changes and basal body temperature can improve confidence in timing. If your tests are always high or never positive, speak with your GP, as this can indicate a need for blood tests or ultrasound tracking. Digital readers can help with interpretation if line tests are hard to compare.
Pregnancy tests detect human chorionic gonadotropin, not LH. Test from the day your period is due for better accuracy and repeat after two days if the result is unclear. Some fertility medicines contain hCG, which can cause a false positive if you test too soon after an injection. Your clinic will advise on the right timing. Keep in mind that an LH surge predicts ovulation but does not guarantee that an egg was released or fertilised. Using both ovulation tests and well timed pregnancy tests gives a fuller view across the cycle.
Frequently Asked Questions About Luteinising Hormone Australia
Can stress affect my LH surge timing in a noticeable way in real life. Yes. Acute or ongoing stress can suppress hypothalamic signals that drive LH pulsatility. People often see delayed surges and longer cycles during stressful periods. Simple stress reduction and regular routines can help stabilise timing over several months.
Do I still ovulate if my LH tests never go positive. Some people ovulate without a clear positive on urine tests because the surge is brief or occurs outside testing times. Blood tests and ultrasound tracking can confirm ovulation if home testing is uncertain. Adjusting test timing to twice daily during the expected window can also help.
How does PCOS change LH results. People with PCOS may have frequent medium level readings or an altered LH to FSH pattern. This can make it harder to pinpoint the true surge. Combining LH tests with symptoms and, if needed, blood tests or ultrasound can improve accuracy.
Could thyroid or prolactin problems affect LH. Yes. High prolactin and thyroid disorders can disrupt the hormones that control LH release. If periods are irregular, your GP may check TSH and prolactin along with LH and FSH to look for a correctable cause.
Is there a best time of day to use an LH test. Many brands suggest late morning or afternoon because LH can rise during the day. Some recommend first morning urine. Follow your kit’s instructions and be consistent. Reduce fluids beforehand to avoid diluting the sample.
What does a faint LH line mean. A faint test line often reflects baseline LH. Track daily and compare photos. The surge is usually when the test line matches or is darker than the control line, or when a digital kit reports a peak. Patterns across days matter more than one result.
Your next steps if you are trying to conceive in Australia
If you are starting out, track cycle dates, cervical mucus, and LH for three cycles. Aim for intercourse on the day of the strongest LH result and the day after. Keep your routine simple and repeatable. If cycles are irregular or you do not see a clear surge after a few months, book a visit with your GP for a discussion and basic blood tests. If you are over 35, consider speaking sooner so you can plan time frames that suit your goals. Support your general health with regular sleep, a balanced diet, and moderate movement. If you choose to use a prenatal vitamin, pick one with folic acid and discuss any extras, such as myo inositol or CoQ10, with your doctor.
Home ovulation and pregnancy tests fit well alongside clinical care. They help you understand your timing and make day to day decisions while you work with your GP or fertility clinic if needed. If you are unsure about your results, bring your records to your appointment. A short review often clears up timing questions and gives you a plan for the next cycle.
References
https://www.healthdirect.gov.au/fertility-and-infertility
https://www.jeanhailes.org.au/health-a-z/periods/menstruation-and-the-menstrual-cycle
https://ranzcog.edu.au/womens-health/patient-information-resources/infertility
https://www.health.vic.gov.au/pregnancy-and-birth/fertility-and-conception
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/ovulation
https://www.nsw.gov.au/health/wnswlhd/services/womens-health
https://www.qld.gov.au/health/conditions/sexual-health/reproductive-health/fertility
https://www.womenshealthtas.org.au
Evan Kurzyp
Evan is the founder of Fertility2Family and is passionate about fertility education & providing affordable products to help people in their fertility journey. Evan is a qualified Registered Nurse and has expertise in guiding & managing patients through their fertility journeys.
