Tracking Ovulation with Irregular Periods

By Andreia Trigo RN BSc MSc

Each month, the female body goes through a hormonal process called the menstrual cycle, to prepare for a possible pregnancy. A regular menstrual cycle lasts 28 days, but every woman is different. Periods are still considered regular if they come every 24 to 38 days. Periods are considered irregular when the cycle is shorter (less than 24 days) or longer (more than 38 days) than average. Periods can also be considered irregular if the cycle length varies more than 20 days from month to month.

Irregular periods may be a sign that something isn’t quite right, especially if your periods used to be regular and are now irregular. However, having irregular cycles doesn’t mean you won’t be able to get pregnant. In this article we talk about how you can track ovulation with irregular periods and identify your fertile window.

How frequent are irregular periods?

Around 14% to 25% of women of reproductive age experience irregular, painful or heavy periods. There are several situations that can be causing your irregular periods:

  •  PCOS: is associated with hormonal imbalance which may result in irregular periods.

  • Pelvic inflammatory disease: is an infection of the reproductive organs and can result in irregular cycles.

  • Thyroid problems: disruption in thyroid hormones can affect reproductive hormones and result in irregular periods.

  • Eating disorders: irregular or missed periods are often a sign of anorexia, bulimia and binge eating disorder. When the body doesn’t get enough nutrients, the reproductive system is one of the first body functions to shut down.

  • Obesity: is associated with more oestrogen being produced by extra fat which can cause missed, irregular or heavy periods.

  • Primary Ovarian Insufficiency: occurs when ovaries stop working normally during reproductive age and can happen as early as teenage years. It can result in irregular periods.

  • Chronic stress: high levels of chronic stress can result in irregular periods.

  • Certain medications: can affect the reproductive cycle.

  • Breastfeeding and perimenopausal women may also experience irregular periods.

Tracking ovulation with irregular periods

Tracking ovulation with irregular periods 

Irregular periods don’t necessarily mean you won’t be able to get pregnant. As long as those are ovulatory cycles – meaning there is an egg ready to be fertilised – you will be able to identify your fertile window and time intercourse to get pregnant.
Even though measuring temperature is a common method of tracking ovulation, it is not an accurate method for predicting ovulation and especially when it comes to irregular periods. This is because basal body temperature monitoring is a retrospective method which only indicates ovulation after it has happened – meaning your fertile window has already ended and you can no longer get pregnant in that cycle.
The most accurate way of identifying your fertile window is measuring Luteinizing Hormone (LH) which is detected in your urine using myLotus. You will notice an increase 24 to 48 hours prior to ovulation, giving you plenty of notice for timed intercourse during the fertile window. You may need to test for more days if your periods are irregular, but once pending ovulation has been detected, you will get a clear and accurate picture of your fertile window.

Noticing changes in your body can also give you indication of when ovulation is about to happen. Some women experience a mild pain in the lower abdomen when they ovulate. You may also notice changes in your cervical mucus as ovulation approaches it becomes similar to egg whites, clear and increased in quantity.


Andreia Trigo RN BSc MSc is a multi-awarded nurse consultant, author and TEDx speaker.  Combining her medical experience and her own infertility journey, she developed unique strategies to help people undergoing similar challenges achieve their reproductive goals. Her mission is to improve accessibility to fertility care and support worldwide at minimal cost to populations. She is the founder of the Enhanced Fertility Programme, the evidence-based programme that improved help for fertility, currently in use by several clinics and patients worldwide.