How to Calculate Ovulation With Irregular Periods

Woman looking at calendar confused, holding stomach, irregular cycles

Updated November 15, 2022 | By Dr. Patti Haebe, NMD

Trying to conceive is complicated enough, let alone paired with irregular cycles. Today we’ll be discussing what to do if you are trying to conceive with irregular cycles. If you have irregular cycles, there are a few questions you can ask yourself to optimize your chances of conceiving. 

Are you regularly irregular or irregularly irregular? 

When it comes to irregular cycles, there can be a variety of different causes and some irregular cycles are problematic patterns while others are not. The best place to start is to figure out if you are regularly irregular, meaning you have periods longer than most women that still come consistently. This could look like periods longer than 35 days but come regularly – plus or minus a few days – ie. a 40 day cycle, then a 38 day cycle, then a 42 day cycle. Women who are regularly irregular have a lesser likelihood of deep-rooted medical problems. It is very possible that this is just a baseline for some reason, and that’s just the uniqueness of you!   

Women who are irregularly irregular often have a more complex situation that results in missed ovulation or scanty ovulation. Many of these women’s cycles will look erratic, for example a 32 day cycle, then 90 days followed by a 72 day cycle. Oftentimes there is a hormonal imbalance causing this and can be anything from thyroid imbalances to PCOS to something more simple such as illness, chronic stress or excessive caloric restriction. If your periods are irregularly irregular, it’s a good idea to discuss this occurrence with your doctor to identify what is causing the fluctuations.


When to take ovulation test with irregular cycles?

If you have irregular cycles, you don’t need an ovulation calculator for irregular cycles; you need a tool as unique as you are! You may be wondering, “How can I get pregnant naturally with irregular cycles?” The key is ovulation tests in combination with the smart technology of the Premom app. These precious little strips can increase your chances of getting pregnant with irregular periods when utilized with Premom’s predictive algorithm. The key is to first identify when and if you are ovulating. Ovulation testing with Premom does this for you

Lh peak and the ovulation time explanation

Ovulation tests take a look at luteinizing hormone (LH) directly, the hormone that is responsible for triggering ovulation. It’s likely that you’ll have to test more days than average but when you examine the way your LH levels appear, you can learn a lot about your body.

Fertility doctors recommend starting ovulation testing right after your period ends and every day until your next period begins to ensure an LH surge is not missed. It’s common for women with irregular periods to need to test upwards of 25 days to catch that LH surge, consistent tracking is essential with irregular cycles.The follicular phase – or first phase – of the menstrual cycle can vary in length commonly among women. However eventually LH levels will surge, ovulation will occur and the second half – or luteal phase – will typically be consistent, around 14 days. 


Ovulating With Irregular Periods

While ovulation tests predict ovulation, some women still have some ambiguous LH surge patterns or perhaps have multiple surges. The best way to confirm ovulation is using a basal body temperature (BBT) thermometer in conjunction with ovulation tests. This will confirm that the LH surge you’ve noticed has resulted in successful ovulation. Your BBT will not rise after ovulation if you have not successfully ovulated. Understand how tracking basal body temperature can be better used as an ovulation tracker.

It’s best to track your ovulation for at least 3 cycles with Premom to get a good picture of what your hormones are doing and to allow the algorithm to improve its accuracy. Make those ovulation tests your best friend, and while you’ll be taking a few more tests than the average woman, you’ll be learning even more about your body each day! The premom app was created to help you better track your cycles and enhance the accuracy of your cycle tracking.

What if ovulation tests don’t indicate ovulation?

If your ovulation tests never show an LH surge or they are consistently at an elevated level that doesn’t seem to go up or down and your basal body temperature never rises in the second half of your cycle, then it’s time to dig a little deeper into abnormal menstruation. 

For example, women with PCOS tend to consistently have irregular cycles and their ovulation tests may often read high throughout the entire cycle and they never – or rarely – get a BBT spike either.  

Meanwhile, women with elevated prolactin levels may have consistently suppressed LH levels that never seem to go higher than a low reading.

Other women may have repeated pulsatile increases in luteinizing hormone as they observe their body attempting to ovulate. They may not see ovulation occur until after 2-3 LH surges have occurred which can be another presentation of PCOS, illness, or stress. 

Either way, if you’ve tested through the entirety of a cycle and not seen an LH peak or not seen a BBT spike,  it’s a good time to talk to your doctor. They may want to do some lab testing to ensure:


  1. Your thyroid is working at maximum capacity 
  2. Your prolactin levels aren’t elevated and suppressing ovulation 
  3. You don’t have elevated male hormone levels (such as testosterone or DHEA-s)
  4. Your blood sugar and insulin levels are well managed (hemoglobin a1c and serum insulin) 

If you’re looking for a natural way to balance your hormones and regulate your cycle, all of the above imbalances can affect ovulation. However, when properly managed by a healthcare professional, irregular cycles should either return to normal cycling or begin regularly resulting in ovulation. So whether it is balancing blood sugar by modifying your diet to a more paleolithic or Mediterranean-based diet or managing your stress levels to decrease cortisol levels and improve your sex hormones levels, there are many natural techniques to get to the root cause and improve your cycles.


Find your fertile window with irregular periods with a free Premom app


 Let’s Sum It Up

If you have irregular cycles, it’s still possible to get pregnant, it’s just more essential than ever to utilize ovulation tests to predict and identify your ovulation which is your best bet for timing intercourse appropriately. Whenever you see that LH begin to surge on your ovulation tests, time your intercourse the 5 days before ovulation and ovulation day to maximize your chances of getting pregnant, even if your LH peak is cycle day 23. Be sure to enter all of your tests into the Premom app using the automatic image capture button from the app the log your levels and visualize your LH trends in it’s unique chart mode.

If you’re not seeing any LH peak and no BBT spike then it’s a good time to dig a little deeper with your doctor to address the root cause.

While women with irregular cycles have an extra hurdle when it comes to TTC, it’s perfectly possible to get pregnant, it just takes one perfect little egg! So make friends with your ovulation tests, wake up to your basal body temperature thermometer, tune into the symptoms of your body and stay consistent. The more information you collect, the more you can learn about your body and better time intercourse to get pregnant quickly.

Premom is here to provide a professional, and personalized expert approach to TTC women with all shapes and sizes of cycles. Download the Premom App today!

Find your fertile window with irregular periods with a free Premom app


About author

Dr Patti Haebe, N.M.D




Dr. Patti Haebe is a results-obsessed naturopathic doctor. She specializes in pre-conception preparation, fertility and hormone optimization. She is committed to root-cause healing through therapeutic supplementation as well as targeted diet and lifestyle modifications.  Her virtual practice, Ocotillo Integrative Medicine, provides integrative consultations worldwide via webcam for those looking to incorporate natural, proactive approaches to their healthcare and fertility journey. Schedule a consultation with Dr. Haebe right through your Premom app! 


Kwak Y, Kim Y, Baek KA. Prevalence of irregular menstruation according to socioeconomic status: A population-based nationwide cross-sectional study. PloS one. Published March 19, 2019. Accessed November 15, 2022. Accessed November 15, 2022.

Dennett CC, Simon J. The role of polycystic ovary syndrome in reproductive and Metabolic Health: Overview and approaches for treatment. Diabetes spectrum : a publication of the American Diabetes Association. Published May 2015. Accessed November 15, 2022.


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