By Dr. Alex García-Faura, Scientific Director at Institut Marquès

How does on affect the other?

How does on affect the other?

 “A lot of women will experience irregular periods throughout their lifetime. This can be due to a number of factors including - fluctuating hormones (particularly during the teenage and pre-menopause years), weight gain/weight loss, stress, over-exercising, or contraceptive medication. However, irregular periods can also be a sign of more serious underlying health problems, such as PCOS or Endometriosis.

Irregular periods can be an indication that a woman will have difficulty conceiving, due to inconsistent ovulation. As the days leading up to ovulation are the ‘fertile window’, any irregularities to your period could mean that the time you are mostly like to get pregnant shifts and shortens.

Whether trying for a baby or not, it is important to speak to your GP if you are concerned about your irregular periods. Irregular periods do not just have an impact on fertility, they can also be indicative of other health issues which you might be unaware of.”


“Many people assume an ‘irregular period’ is when a period arrives late or is earlier than usual. However, an ‘irregular period’ can also encompass lots of other factors, such as a very heavy or light menstrual flow, an absent period, an inconsistent cycle, extreme cramping, bloating, or nausea.  

Whilst the odd irregular period shouldn’t cause too much concern, if your period is consistently irregular, then not only can it be uncomfortable and unpleasant, but it can also lead to fertility issues and mean there are potentially more serious issues under the radar.”


“PCOS (Polycystic Ovary Syndrome) is caused by immature follicles which grow on the ovaries and subsequently cause an imbalance of hormones. This can impact ovulation, and therefore make it challenging for women with the condition to conceive. Women with PCOS may find that they experience irregular periods as a result of this imbalance of hormones.

Whilst irregular periods are a key symptom of PCOS, there are also other signs to look out for. Common symptoms can include weight gain, hair loss on the head, excessive hair growth on the rest of the body, and acne.

Although there is no cure for PCOS, the condition can be managed. Periods can often be regulated through the use of the contraceptive pill, and there are also drugs available which can help stimulate ovulation, such as Clomid, if you are trying to fall pregnant.”


“Endometriosis is a medical condition which occurs when the tissue lining a woman’s uterus (called the endometrium) grows in other areas of the body. This can include the fallopian tubes, the ovaries, or other abdominal organs such as the bladder or the intestines.

This tissue acts in a similar way to the tissue which is found in the lining of the womb, and copies the menstrual process. Each month these cells build up, before breaking down and bleeding, in the same way you would have your period. However, unlike a period which is discharged through the vagina, this blood has no way to escape. Endometriosis can be characterised by irregular, heavy, and often painful periods.

It is important to remember that Endometriosis does not necessarily mean that you will be unable to have children however, depending on the patient and the severity of the condition, it can create some challenges if you are trying to conceive.

As the severity of the Endometriosis increases, scar tissue (also known as adhesions) is more commonly found - and so the chance of natural conception decreases. This is because the increased number of adhesions means there is higher possibility the egg will get trapped and prevented from travelling down the Fallopian tube.

Endometriosis is classified into minimal, mild, moderate, and severe using the American Fertility Society Revised Classification of Endometriosis (AFS) score, and this score helps dictate the chance of conceiving naturally.

Unfortunately, there is no cure for Endometriosis however, there are a number of ways in which patients can manage their symptoms effectively. There is also surgery available to remove scar tissue, which can help increase chances of falling pregnant.


“Although PCOS and Endometriosis are the most serious medical conditions associated with irregular periods, they are not the only two reasons why women will experience an irregular cycle/ovulation - which can then in turn lead to difficulty conceiving.

The majority of women have a ‘fertile window’ when conception is most likely to occur. Typically these are the days immediately prior to and following ovulation. During a ‘regular’ menstrual cycle (lasting 28 days) most women will ovulate around day 14 – half way through your cycle. This means the fertile window would be between days 10-15. However, if you suffer from irregular ovulation (often symptomised by irregular periods), this means that the time frame can change.

For example, if you experience a longer menstrual cycle (more than 35 days), it is likely your window of ovulation is smaller and the likelihood of you ovulating regularly decreases.

There can be a number of natural remedies which can help regulate your cycle, for example moderately exercising, eating a healthy diet and quitting smoking. On top of this, fertility drugs can help stimulate ovulation and can be prescribed by a specialist if you are trying for a baby and it is found you are not ovulating.

Finally, it can be worth tracking your cycle using fertility app, to help you better understand your fertility and the key times of the month when you are most likely to fall pregnant.

It’s important to remember that if you have an irregular cycle, this does not mean that you will be unable to fall pregnant. Do seek advice from a fertility specialist who will be able to offer advice and support.”

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