Women are different in many ways, whether it be their height, their eye colour, what they believe in or even the type of menstrual cycle they experience.

As a fertility specialist, one of the most important things I am interested in if a woman is having trouble trying to fall pregnant is her menstrual cycle. Why? Because it can greatly impact on their chances of falling pregnant.

Defining what a period is and what is normal
The terms “period” or “menstruation” refer to the time, usually each month, when a woman experiences a discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. A menstrual cycle is more than just a period or menstruation; it involves several changes, including the rise and fall of hormones, the thickening of the lining of the uterus, and the maturation of an egg, which is required for pregnancy. An egg is usually released each cycle from an ovary and, if fertilised, the thickened lining of the uterus provides nutrients to the developing embryo after implantation. If pregnancy does not occur, the lining is released in the form of a period. The average menstrual cycle length is 26 to 32 days. Day one of the cycle is considered to be the day bleeding begins.

Why is it important to know your menstrual cycle?
Knowing your menstrual cycle is important in determining when you are ovulating (releasing an egg from the ovary) and hence knowing the most fertile and optimum time in the cycle to fall pregnant. If your period is regular and the length is the same every month, then you can calculate ovulation by counting back 14 days from the end of the cycle. So, if your cycle is 32 days long, ovulation will occur about day 18; or if your cycle is 28 days long, ovulation will occur about day 14. If your cycle is irregular and changes length each month, it is much harder to calculate when ovulation is occurring.

What can a long menstrual cycle indicate?
A long menstrual cycle can indicate ovulation is not occurring (known as anovulation), or occurring irregularly. A long cycle is considered one that lasts more than 32 days. There are many potential causes, including thyroid issues, hormone problems (particularly prolactin) and, commonly, polycystic ovary syndrome (PCOS).

Excessive menstrual bleeding?
A normal period lasts between 5 and 7 days. Heavy or prolonged bleeding can be caused by a number of factors, such as fibroids, polyps, infection in the uterus or cervix, thyroid problems or, on rare occasions, blood clotting.

What if I never menstruate?
Without menstruation, ovulation is usually not occurring and therefore conception is difficult without intervention. The most common cause of this is being overweight or having a high body mass index (BMI), but it can also be due to being underweight and having a low BMI. There are other, rare medical causes as well, including problems with the uterus lining and formation.

What can be done?
A woman’s menstrual cycle is determined by a complex interaction of hormones, so any hormone imbalance can make a cycle irregular. Several factors can impact on a woman’s menstrual cycle, including weight, stress, medical conditions and age. Although irregular cycles are usually not dangerous, it is important to determine the reason with your medical specialist and if possible actively treat or rectify the cause. Women with irregular cycles can still conceive by themselves, but it is a little more challenging to pinpoint when ovulation is occurring and hence determine the prime fertility window each cycle. Sometimes, the use of clomiphene medication can help the body return to a normal ovulation cycle. This medication stimulates the ovaries and encourages regular ovulation. More-advanced assisted reproductive technology (ART), such as IVF and donor egg treatment for premenopausal patients, can be considered if required.