Read more from Fertility & cycle health

Irregular periods and pregnancy

24 February 2020

The causes of irregular periods can be different for each person. Every month, the female body goes through a hormonal process called the menstrual cycle, to prepare for a possible pregnancy. The average menstrual cycle lasts around 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 period symptoms 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 how you can identify your fertile window.

What is an irregular period?

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

How to calculate your ovulation with irregular period

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.

How to get pregnant with irregular period

The most accurate way of identifying your fertile window is measuring Luteinising Hormone (LH) which is detected in your urine using myLotus. You will notice an increase 24 to 36 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 an indication of when ovulation is about to happen. Some women experience 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. 


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