Tracking your hormones and doing the calculations can sometimes be challenging when conceiving. But, whether you can estimate your due date or intend to plan a suitable time for intercourse, you will need to know how to do the math. The Luteal Phase is also referred to as the secretory phase. Fortunately, some simple math is all you need to calculate the essential part of your cycle, known as the Luteal Phase. This phase is a crucial indicator of fertility and only requires a simple formula to figure things out. Keep reading to learn how you can determine the phase and why this information is crucial for your pregnancy journey.

What’s a Luteal Phase?

A menstrual cycle is usually divided into the follicular and luteal phases . The stage of the menstrual cycle that starts after you ovulate is known as the luteal phase. This part is named after the formed structure instead of the follicle from which an egg was released. This phase is followed by the follicular phase, which ends when bleeding starts. In the luteal phase, the hormone progesterone is higher than in the follicular period. Since the secretory phase is a vital indicator of fertility, knowing what happens during it and how it will play out in your cycle is essential. For this reason, you need to track your menstrual cycle and monitor fertility signs in your body. The information you get will be useful if you are trying to conceive.

Luteal phase calculator

Every woman’s menstrual cycle varies , lasting for 21-35 days. Since menstruation occurs in a fairly regular sequence, it’s possible to calculate the luteal phase by tracking the cycle and noting important dates, such as the 1st day of the previous period and the ovulation date. When you plug those numbers into a formula, you will determine the length of the Luteal Phase. What aspects do you need to know? To know the exact length of your luteal phase, you need to determine a couple of important dates before working out anything:

• The actual ovulation date before your period
• The day your menstrual period begins

Once you know the dates, you must plug them into the following simple formula to determine the span of your Luteal Phase.

Once you know the dates, you must plug them into the following simple formula to determine the span of your luteal phase:

• The actual [ovulation date] before your period
• The day your period begins

How to Calculate Your Luteal Phase

Start by recording the day you ovulate and the first day of your next period. Subtract the ovulation day from the start of your period to determine the length of your luteal phase. For example, if you ovulate on the 14th and your period begins on the 28th, your luteal phase is 14 days.

This method is most accurate with regular cycles. If your cycle varies, the result is an estimate. In such cases, consult a healthcare professional for personalised guidance on your cycle.

What is a normal secretory phase?

A standard Luteal Phase usually lasts 11 to 17 days and is a vital marker of fertility. Any number outside this duration is abnormal and will negatively affect your chances of conceiving. When implantation occurs, the fertilised egg requires enough time to accomplish this.

What if you have a short secretory phase?

Any phase less than ten days is considered short and could signify luteal phase deficiency. A short phase usually affects fertility as it does not allow the body to develop enough to support the pregnancy. In most cases, this is associated with a progesterone production deficit. Progesterone is a hormone that prepares the body for pregnancy and ensures you get and stay pregnant. It also thickens the uterus lining so the fertilised egg can be implanted properly. If your luteal phase is short, your uterine lining will not get enough time to develop the right thickness to receive the fertilised egg or support an embryo, and you will find it harder to maintain a pregnancy.

Progesterone’s Role in the Luteal Phase

After ovulation, the ovary transforms as the follicle remnants become the corpus luteum. This temporary gland is essential for fertility, releasing progesterone to prepare the uterine lining for pregnancy by encouraging tissue growth and maintaining a nutrient-rich environment.

Tracking Basal Body Temperature

Measuring your basal body temperature (BBT) is a reliable method to understand your menstrual cycle and pinpoint ovulation. Use a digital basal thermometer to record your temperature each morning upon waking, before getting out of bed, after three to four hours of uninterrupted sleep. Consistent timing is crucial, as small routine changes can affect results.

During the follicular phase, your BBT stays steady at a lower level. After ovulation, it rises by about 0.2°C to 0.5°C due to increased progesterone in the luteal phase. Record your temperature daily in a dedicated journal or a trusted fertility tracking app to identify this shift. A sustained rise in temperature continues until just before menstruation. If conception occurs, the temperature remains elevated beyond this point. For best results:

• Measure at the same time each morning.
• Avoid disrupted sleep, illness, or alcohol consumption, which can skew readings.
• Compare your BBT data with other fertility signs, such as changes in cervical mucus, to get a complete view of your cycle.

If you notice unexpected patterns or have concerns about your cycle, consult a healthcare professional. Australian fertility experts widely recommend this method as part of tracking reproductive health.

In a cycle without pregnancy, the lack of sustaining signals—especially human chorionic gonadotropin (hCG)—triggers luteolysis, the process where the corpus luteum breaks down. As it fades, progesterone levels drop, leading to the shedding of the endometrial lining and the start of menstruation. However, if fertilisation occurs, early hCG production maintains the corpus luteum, prolonging progesterone release to support early pregnancy.

Understanding these hormonal changes clarifies how the corpus luteum affects the menstrual cycle, providing useful information for those tracking their fertility.

Can a short luteal phase be fixed?

If you notice your luteal phase is shorter than expected, it’s important to address the issue with professional guidance. Treatment strategies vary depending on the underlying cause of the hormone imbalance. Some women explore options such as hCG or progesterone supplementation to help support a balanced hormonal environment, while others may consider natural and lifestyle approaches. Regardless of the chosen method, consulting a qualified healthcare provider is essential to tailor treatment to your specific needs and to monitor any potential side effects.

If you have realised your Luteal Phase is short, you must wonder if you can fix the problem. The treatment will vary depending on the primary cause of the progesterone deficiency. Taking hCG supplements has successfully helped many women treat the condition. Supplementation causes your body to release more progesterone, increasing the luteal phase. A healthcare provider can prescribe progesterone to counter the deficiency in other cases. Progesterone is available in different dosage forms, including rectal, oral, and injectable. But progesterone supplementation has unwanted side effects like headaches, bloating, abdominal cramping, fatigue, diarrhea, and nausea. Most women do not like these side effects, so they seek alternative solutions.

Ways to Support a Healthy Luteal Phase Naturally

Taking a well-rounded approach to wellness supports hormone regulation and reproductive health. Incorporating locally sourced Australian foods and practices enhances these lifestyle changes, fitting smoothly into your daily routine.

Nourish with Australian Superfoods

• Include Healthy Fats: Omega-3-rich foods support hormone production. Add Australian produce like avocados, macadamia nuts, and flaxseeds to your diet to boost progesterone levels naturally.
• Embrace Native Fruits and Vegetables: Choose native foods like Kakadu plums, finger limes, and bush tomatoes, which are rich in vitamins and antioxidants that support hormonal balance.
• Choose Whole Grains and Legumes: Incorporate whole grains like quinoa and barley, and legumes such as chickpeas and lentils, which provide essential nutrients for hormone regulation.

Engage in Local Physical Activities

• Outdoor Exercise: Take advantage of Australia’s diverse landscapes by bushwalking, beach yoga, or coastal cycling. These activities promote blood circulation and help maintain a healthy weight.
• Community Sports: Join local sports like netball, cricket, or swimming clubs. Team activities provide social interaction, boosting overall well-being.

Practice Stress Reduction Techniques

• Mindfulness and Meditation: Mindfulness meditation reduces stress-related hormonal imbalances. Join local meditation groups or attend community workshops.
• Yoga and Pilates: Popular in Australia, yoga and Pilates help stabilise hormone levels. Many studios offer classes for all levels, focusing on balance and relaxation.
• Reconnect with Nature: Gardening or visiting national parks can alleviate stress. These activities are widely practised in Australian communities for their therapeutic benefits.

Prioritise Restful Sleep

• Establish a Sleep Routine: Aim for 7–9 hours of quality sleep each night. Create a relaxing bedtime routine, such as reading, listening to calming music, or practising gentle stretching.
• Improve Your Sleep Environment: Keep your bedroom cool, dark, and quiet. Use natural fibres for bedding, which suit Australia’s climate.

Stay Hydrated with Quality Water

• Optimal Hydration: Drink plenty of water daily to support metabolism and hormonal balance. Australia’s high-quality tap water makes staying hydrated easy and accessible.

Incorporating these local practices supports a healthy luteal phase and enhances your fertility journey. If you have concerns about menstrual irregularities or hormonal health, consult a qualified Australian healthcare professional for personalised advice.

Expert Perspectives

Australian fertility specialists emphasize that understanding the luteal phase is essential for reproductive health. These recommendations are based on evidence-based guidelines from organisations like the Royal Australian and New Zealand College of Obstetricians and Gynaecologists. By incorporating expert insights, our guidance relies on solid research and local clinical expertise, providing reliable advice for your fertility journey.

What if you have a long Luteal Phase?

If your Luteal Phase is within the normal range, you will not be concerned because it’s much easier to conceive. When you track your cycle, you will know when things are off or out of range. A long luteal phase could mean you are expectant and haven’t yet figured it out. If you experience worrisome symptoms, such as heavy periods or severe pain during sex, you should consider seeing a doctor. The journey to understanding fertility is filled with questions and uncertainties. Fertility2Family is here to provide clarity and support. Our blog offers a wealth of articles, like this one on the Luteal Phase, to help you unravel the complexities of fertility. To further assist you on your journey, we offer a range of fertility kits designed to help you confidently track your cycle, providing you with the practical tools you need to navigate your fertility journey.

Evan kurzyp

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.