Why are my periods irregular?

A menstrual cycle is one of the more informative things a body produces. It reflects the brain's hormonal signalling, the ovaries' response, thyroid function, insulin handling, nutritional status and stress load — all at once, every month. When it becomes unpredictable, that is data rather than an inconvenience.

It is worth being precise about what "irregular" means. A cycle runs from the first day of one period to the first day of the next, and 21 to 35 days is the usual adult range. A few days of variation between months is ordinary. What deserves attention is a cycle consistently outside that range, gaps of three months or more, or a clear change from your own long-standing pattern.

PCOS is the commonest cause in the reproductive years. Polycystic ovary syndrome affects a substantial proportion of Indian women and typically produces cycles that are long or skipped, alongside acne, hair growth on the face or chin, thinning at the scalp, and weight that is difficult to shift. Underneath it usually sits insulin resistance, which is why it travels with a family history of type 2 diabetes so often. It is a metabolic condition as much as a gynaecological one, and it is diagnosed on a defined combination of findings after other causes are excluded — not on an ultrasound picture alone.

Thyroid disease. Both underactive and overactive thyroid disturb the cycle, and hypothyroidism in particular is common among Indian women. It may lengthen cycles, make them heavier, or stop them, usually with fatigue, cold intolerance, hair fall and weight change alongside. It is one inexpensive test.

Raised prolactin. The hormone that supports breastfeeding will suppress ovulation when it is elevated at other times. Causes include a small benign pituitary growth, an underactive thyroid and several medicines, including some used for nausea and for mental health. Milky nipple discharge outside breastfeeding is the giveaway, and headaches or changes in vision alongside it need prompt review.

Weight, energy availability and stress. Substantial weight loss, low intake relative to training load, heavy exercise, shift work, illness and sustained emotional stress can each suppress the signal from the brain that drives the cycle. Weight gain works through a different route — more oestrogen produced in fat tissue — and disturbs the cycle too.

The perimenopausal transition. From the early forties, and sometimes late thirties, cycles typically shorten, then lengthen, then skip, over a transition of four to eight years. Hot flushes, disturbed sleep and mood changes often accompany it. Indian women commonly reach menopause somewhat earlier than Western averages, so this arrives sooner than many expect.

Other causes worth naming. Pregnancy, contraception and recently stopped hormonal contraception, structural findings such as fibroids or polyps, and primary ovarian insufficiency where periods stop before 40. Rarely, other endocrine conditions. This is why irregular cycles are assessed rather than attributed.

ⓘThis information is educational and not a diagnosis.

Some patterns need attention quickly rather than at the next convenient time.

Seek same-day care for bleeding heavy enough that you are changing protection every hour for several hours, for severe pelvic pain, for pain with fever and unusual discharge, or for a positive pregnancy test accompanied by pain or bleeding.

Arrange prompt assessment for any bleeding between periods or after sex, and for any bleeding at all after menopause — that last one is important and is investigated regardless of how light it is. Milky discharge from the nipples when not breastfeeding, particularly with headaches or changes in vision, also warrants early review.

No period for three months or more, when pregnancy and breastfeeding are excluded, is worth investigating rather than waiting out. So are periods that stop before the age of 40, because the assessment and the implications differ.

Beyond these, it is reasonable to see a doctor when cycles have been unpredictable for three months or longer, when irregularity comes with acne, unwanted hair growth or difficulty losing weight, or when you are planning a pregnancy and cycles are not settled.

Start tracking properly, because recollection is unreliable here. Record the first day of each period, how many days of bleeding, how heavy, and any pain — a simple app or the back page of a diary both work. Three months of that changes an assessment completely, and often shortens it.

Note what travels alongside. Acne, hair on the face or chin, thinning at the crown, skin darkening at the neck or armpits, weight changes, energy, mood, sleep, temperature tolerance, bowel habit and any nipple discharge. These are what point a doctor toward the right tests rather than a broad and expensive panel.

If pregnancy is possible, a home test is a sensible first step regardless of what else you suspect.

For testing, a reasonable initial set is thyroid function, prolactin, a full blood count with ferritin, and — where PCOS is being considered — testosterone, an HbA1c and a fasting lipid profile, with a pelvic ultrasound if indicated. Timing matters for some of these, which is one reason they are better ordered through a consultation than picked from a package.

Meanwhile, the things that genuinely help are unglamorous: regular sleep, adequate protein, resistance training twice a week, and enough energy intake to match what you are doing. Where insulin resistance is part of the picture, those changes act on the cause rather than on the symptom.