Updated: May 12, 2019
The 'normal' menstrual cycle is around 21-35 days from the start of one period to the start of the next. While it is more common NOT to be the kind of woman who can 'set a clock' by her period, and cycles vary naturally by a few days in most healthy women, cycles that vary widely from or are very far apart (45-60 days) often have an underlying cause.
Why is my period irregular?
The occasional missed period can occur due to stress as this acutely interferes with normal ovulation, and many women have experienced this effect. Pregnancy is also a common cause of a missed period when previously regular and should be excluded!
Irregular cycles, especially when far apart (called oligoanovulation) can be caused by problems in any part of the hormonal chain that controls the ovaries, termed the gonadal axis. This includes brain causes, where the hormones that stimulate the ovaries are very low most often due to severe stress, severe medical problems, loss of weight to a very low level and intense exercise, ovarian causes where the ovaries don't respond normally to signals from the brain, and due to other medical or endocrine (hormonal) disease such as significant thyroid problems.
Of these, the most common is a condition called polycystic ovarian syndrome, in which the gonadal axis and ovaries do not function as they should, leading through complex pathways to varying combinations of rare or absent ovulation, wide intervals between periods, acne, high male hormones, excess hair, insulin resistance, diabetes and infertility. It is a common condition, and increasing in our community due to its link to obesity but it is important to be reassured that it is treatable.
Treatment vary depending on whether the goal is to regulate the menstrual cycle, treat acne or hair, lose weight, get pregnant, protect the lining of the womb from becoming too thick, or manage metabolic associations.
How do I work out the cause?
In most cases the cause can be determined by asking you questions regarding your diet, lifestyle, stress levels, weight change, and symptoms of potential causes, a brief physical examination and blood tests and an ultrasound. Then an individualised plan to manage your irregular periods is made, considering the cause, your health, you desires and the options available.