Why Is My Period Late? Causes, Tests, and When to Worry

• A normal cycle is 21 to 35 days. Compare a late period to your own usual cycle, not to a textbook 28-day one.
• In any sexually active woman of reproductive age, pregnancy is the first cause to rule out, regardless of contraception, because no method is 100% effective.
• If you are not pregnant, the common culprits are stress, weight or exercise changes, recent illness, PCOS, thyroid disease, and high prolactin.
• Three or more missed cycles, or any missed period with red-flag symptoms, deserves a doctor's evaluation.
• Most causes are identifiable with simple, inexpensive tests (a urine pregnancy test, TSH, prolactin, and a pelvic ultrasound) and treatable.
• PCOS and thyroid disease are especially common in Indian women and easily missed, so the threshold to test should be low.

Before calling any cycle "late," it helps to know how much variation is normal. Cycles shift by a few days month to month even in perfectly healthy women, so small changes are the rule, not the exception.

Per ACOG, NICE, and FOGSI, a normal menstrual cycle is 21 to 35 days long, measured from the first day of one period to the first day of the next. (Cycle day one is the first day of full flow, not spotting.) Bleeding usually lasts three to seven days, with a total flow of around 30 to 80 ml.

The key is to compare a cycle to your usual, not to a 28-day textbook ideal. If your cycles are typically 26 days and one arrives on day 33, that is genuinely late for you, even though 33 days is still medically normal. Tracking your cycles for three to six months, whether on a paper calendar or an app, gives you a personal reference range. Our guide to hormone levels during the cycle explains the hormonal pattern behind that rhythm.

Some women have naturally irregular cycles that swing by 10 to 20 days without any underlying problem. This is especially common in the first two years after the first period and in the perimenopausal years (the five to ten years before menopause, which for Indian women per FOGSI data often begins in the early-to-mid forties). In those life stages, the question shifts from "is this a problem?" to "is the pattern getting worse, or are there other worrying symptoms?"

As a working rule: in a previously regular adult, a period more than seven days past the expected date counts as delayed, and three or more missed cycles in a row (or any missed cycle with red-flag symptoms) warrants formal evaluation. If you are unsure whether your cycle is just irregular, what irregular periods can mean breaks down the patterns worth watching.

In any sexually active woman of reproductive age, pregnancy is the first thing to rule out, regardless of contraception, because no method is 100% effective and pregnancy is time-sensitive: it changes every decision that follows.

The right first step is a home urine pregnancy test. Brands like Prega News, i-Can, and Velocit (roughly ₹50 to ₹150 at any pharmacy, no prescription) detect the hormone hCG with over 99% accuracy when used correctly and at the right time.

The right time is at least one week after the missed period, using first-morning urine, which is most concentrated. Testing too early can give a false negative because hCG may not yet be high enough to detect. If the first test is negative but your period still hasn't come, repeat it in three to five days, or ask for a quantitative blood beta-hCG (around ₹300 to ₹700 at most labs), which is more sensitive and turns positive earlier. Our guide to reading a pregnancy test correctly covers timing and faint lines.

Even consistent contraception users can become pregnant. Typical-use failure rates per WHO and ACOG are around 9% per year for the combined pill (mostly missed pills), about 18% for male condoms, under 1% for copper and hormonal IUDs, and around 1% for sterilisation. Emergency contraception taken within 72 hours of unprotected sex reduces but does not eliminate the risk.

If the test is positive and the pregnancy is wanted, the next step is obstetric care. If it is not wanted, medical termination of pregnancy is legal in India up to 24 weeks under the MTP (Amendment) Act, 2021, and is safest through a registered MTP centre.

One India-specific barrier matters here: many unmarried women delay testing because of stigma, even when sexually active, which pushes back diagnosis and care. The medical position is unambiguous, any sexually active woman with a late period needs a pregnancy test first, regardless of marital status, and that test is private and accurate at any pharmacy.

Stress is one of the most common and most under-recognised reasons for a late period in women with no underlying disease. The mechanism is well established: stress hormones like cortisol and CRH suppress the hypothalamus's pulsing release of GnRH, which dials down the LH and FSH signals to the ovaries, delaying or skipping ovulation, which delays the next period.

The kinds of stress that can shift a cycle include acute events (bereavement, a job loss, a major exam, illness in the family), chronic strain (a demanding job, caregiving, money worries), sleep disruption (shift work, insomnia), and changes in routine (travel, especially across time zones). India adds its own often-dismissed stressors: marriage-related pressure, fertility expectations after marriage, joint-family dynamics, and the double shift of paid work plus household and caregiving duties. Our deeper read on how long stress can delay your period explains the typical timelines.

Weight changes matter too. Losing or gaining more than 5 to 10% of body weight over a few months disrupts cycles, because fat tissue produces oestrogen and rapid swings unsettle the whole axis. Heavy exercise can do the same: the female athlete triad (low energy availability, menstrual disruption, low bone density) shows up in runners, dancers, and women combining restrictive eating with intense training, covered in our guide to the female athlete triad. A recent high fever (dengue, typhoid, COVID, flu) can also push the next period back by a cycle or two, and this is usually self-limiting.

The fix is to address the underlying factor, and cycles usually return within one to three months. Approaches with reasonable evidence include regular moderate activity (150 minutes a week of moderate or 75 minutes of vigorous exercise per WHO, ACOG, and FOGSI), cycle-friendly yoga and breathing practices, consistent seven-to-nine-hour sleep, and structured stress reduction or therapy where needed. The cultural habit of brushing off women's stress as "not a real cause" is harmful, because it delays both recognising the problem and treating it.

Polycystic ovary syndrome (PCOS) is one of the most common hormonal disorders in reproductive-age women and is especially prevalent in India, with FOGSI-cited estimates of roughly 10 to 20% depending on the criteria and population. It is a leading cause of chronically late or absent periods because the hormone imbalance behind it blocks regular ovulation.

Diagnosis uses the Rotterdam criteria, which require two of three features: infrequent or absent ovulation (cycles longer than 35 days or fewer than nine periods a year), signs of high androgens (acne, excess facial or body hair, scalp hair thinning, or raised testosterone on a blood test), and a polycystic appearance on ultrasound. The underlying driver is often insulin resistance, which raises ovarian androgen production and prevents a single follicle from maturing and ovulating, our explainer on PCOS and insulin resistance goes deeper. The result is irregular periods plus androgen symptoms like excess facial and body hair and acne.

The workup includes a focused history, a physical exam (BMI, waist, signs of high androgens), and blood tests (TSH, prolactin, testosterone, DHEAS, LH, FSH, oestradiol, fasting glucose and insulin, lipids) plus a pelvic ultrasound, costing around ₹2,000 to ₹4,000 at most Indian labs. Treatment depends on your symptoms and goals: the combined pill regulates cycles and reduces androgen symptoms, metformin improves insulin resistance, and weight, diet, and exercise changes genuinely help and are first-line per FOGSI for overweight women, see evidence-based PCOS weight loss in India. For more on the condition itself, read PCOD vs PCOS explained and the reassuring PCOS isn't your fault.

One point is often missed: in PCOS, long stretches without a period mean the uterine lining sits under unopposed oestrogen, which over years can raise the risk of endometrial overgrowth and, rarely, endometrial cancer, especially with extra risk factors like obesity. ACOG and FOGSI therefore recommend that women with PCOS have at least four periods a year, spontaneously or induced with cyclical progesterone or the pill, to protect the lining. PCOS-related missed periods are not just an inconvenience, they have real long-term implications that benefit from active management.

Thyroid disease is the second most common hormonal cause of a late period after PCOS, and both an underactive thyroid (hypothyroidism) and an overactive one (hyperthyroidism) can disrupt cycles. Hypothyroidism is particularly common in Indian women, with ICMR data showing TSH abnormalities in roughly 11% of reproductive-age women, driven mainly by autoimmune thyroid disease (Hashimoto's), and historically by iodine deficiency in some regions.

An underactive thyroid disrupts cycles in several ways: it slows oestrogen clearance, and the body's compensatory TRH stimulates prolactin, which in turn suppresses ovulation. The result varies, some women have late or absent periods, others have heavy ones. Look for fatigue, cold intolerance, weight gain, constipation, dry skin, hair loss, and low mood, symptoms often dismissed as ordinary tiredness. Our guide to hypothyroidism in Indian women covers the full picture.

An overactive thyroid more often causes light, infrequent periods, along with heat intolerance, weight loss despite a good appetite, palpitations, anxiety, and tremor. Graves' disease is the most common cause in younger women.

Diagnosis for both is a simple TSH blood test (with reflex T4 and T3 if abnormal), around ₹250 to ₹500. This should be ordered for any woman with unexplained late periods, particularly if other symptoms point to the thyroid. Treating hypothyroidism with levothyroxine (Thyronorm, Eltroxin, very inexpensive) usually restores cycles within one to three months as the TSH normalises; antithyroid medicines do the same for an overactive thyroid. Postpartum thyroiditis affects roughly 5 to 10% of women in the year after delivery and is often mistaken for ordinary new-parent exhaustion. The threshold to test should be low, the test is cheap and the diagnosis is easily treated.

Raised blood prolactin (hyperprolactinaemia) is the third common hormonal cause of late periods, and it is worth considering specifically because it is straightforward to diagnose and usually treatable. Prolactin is the hormone that drives milk production and is normally low in women who are not pregnant or breastfeeding. When it is high, it suppresses ovulation, causing late or absent periods, sometimes with milky breast discharge (galactorrhoea), headaches, or visual changes.

Common causes include a benign pituitary tumour (a prolactinoma), certain medications (some antipsychotics like risperidone and haloperidol, the anti-nausea drug metoclopramide, and some others), an underactive thyroid, and physiological states like breastfeeding. The diagnosis is a morning blood prolactin level (around ₹500 to ₹1,000), drawn before eating or a breast exam, since both can transiently raise it. Our detailed guide to high prolactin in women explains the workup and what the numbers mean.

If prolactin is high, a pituitary MRI looks for an adenoma. Treatment is usually medical, with dopamine agonists such as cabergoline (preferred for its twice-weekly dosing and gentler side effects) or bromocriptine, which normalise prolactin in over 90% of cases, with cycles typically returning within two to three months. Surgery is rarely needed. For medication-related high prolactin, the answer is to review and, where possible, switch the offending drug with the prescribing doctor.

Rarer hormonal causes of a late period include premature ovarian insufficiency (affecting around 1% of women under 40), Cushing's syndrome, and other pituitary or hypothalamic conditions, all of which need specialist evaluation if the picture suggests them. To understand where these fit, hormone levels during the cycle sets out the normal hormonal map against which these abnormalities show up.

Perimenopause is the transition in the years before menopause, marked by progressively irregular cycles, often longer ones, then skipped months, and eventually no periods at all. The average age of menopause in Indian women is around 46 to 48 years per FOGSI data, a little earlier than the global average of about 51. Because the transition typically begins five to ten years earlier, perimenopausal cycle changes can start in the late thirties or early forties for many Indian women.

The driver is the natural decline in the ovaries' egg reserve and their response to pituitary signals, which makes ovulation irregular. Typical patterns include cycles that gradually lengthen (28 days to 35 to 40 days, then skipped months), wide swings month to month, changes in flow, and new symptoms like hot flushes, night sweats, mood changes, sleep disruption, and vaginal dryness. Our guide to what perimenopause is and the India-focused perimenopause symptoms in Indian women cover what to expect.

Evaluation in these years still means ruling out pregnancy (which can happen as long as periods occur, even if irregular) and thyroid disease, which becomes more common with age. But for most women, the irregular pattern is simply the natural march toward menopause and needs only reassurance and symptom management. Hormone replacement therapy is appropriate and safe for most women with significant symptoms within ten years of menopause, per current ACOG and NICE guidance, and both FOGSI and the Indian Menopause Society endorse its use in suitable women, yet Indian women are sometimes under-prescribed it because of lingering hesitancy. A DEXA bone-density scan around menopause helps assess osteoporosis risk.

Many medications can cause late or absent periods, so a careful medication history is part of any evaluation. Hormonal contraception leads the list and is often misunderstood: the DMPA injection causes no periods in over half of users by one year, the hormonal IUD (Mirena) does so in about 20%, and implants commonly cause irregular bleeding. The combined pill usually gives a predictable withdrawal bleed, but skipped bleeds can occur, especially with continuous use.

Starting or stopping any hormonal method is a common reason for a temporarily late period. After stopping the pill, the next natural period can be delayed by one to three months as your own cycle re-establishes, this is normal and does not signal a future fertility problem, as our guide to what happens after stopping birth control explains. After stopping DMPA, cycles can take six to twelve months to return; after IUD removal or stopping an implant, they usually return within one to two months. A newly started method commonly causes irregular bleeding for the first three to six months.

Other drugs to consider include prolactin-raising antipsychotics (risperidone, haloperidol) and anti-nausea metoclopramide, chemotherapy and immunosuppressants, high-dose steroids, and some anticonvulsants. Because many medicines are sold over the counter in India, your history should cover everything you take, including ayurvedic preparations and online supplements, which may have hormonal effects or undeclared ingredients. The fix is usually to identify and switch the offending drug with the prescribing doctor, after which cycles typically settle within one to three months. If you are on a prolactin-raising psychiatric medicine, your gynaecologist and psychiatrist may coordinate a switch within the same class. For using hormones deliberately to control your cycle, see using the pill to regulate periods.

A simple framework helps. For a single late period under two weeks past the expected date, with a negative pregnancy test and no other symptoms, it is usually fine to wait one to two weeks and address any obvious recent stressor. For a delay beyond two weeks, three or more missed cycles in a row, or any red-flag symptom, see a gynaecologist. With a positive home pregnancy test, arrange obstetric care.

See a doctor sooner if you have any of these alongside a missed period:

A standard gynaecology workup for a late period is straightforward, inexpensive, and high-yield, most women turn out to have an identifiable, treatable cause. It includes a focused history (menstrual, pregnancy and contraception history, symptoms, stressors, weight changes, medications, and family history of PCOS, thyroid disease, or early menopause), a physical exam, and blood tests, typically TSH (₹250 to ₹500), prolactin (₹500 to ₹1,000), LH and FSH (₹800 to ₹1,500 together), and oestradiol, with testosterone, DHEAS, fasting glucose, HbA1c, and a blood count added when relevant.

A pelvic ultrasound (transvaginal in sexually active women, transabdominal otherwise; around ₹1,000 to ₹2,500) checks the uterus and ovaries for polycystic morphology, fibroids, and other findings. At a private clinic, expect roughly ₹2,000 to ₹4,000 for the consultation plus ₹3,000 to ₹5,000 for tests and imaging; government PHCs, CHCs, and district hospitals offer the same workup free or at nominal cost, though waits may be longer. Tele-gynaecology consultations (around ₹600 to ₹1,500) are a convenient first step, though exams and imaging still need an in-person visit.

Treatment follows the diagnosis: cycle regulation for PCOS, levothyroxine for hypothyroidism, dopamine agonists for high prolactin, lifestyle changes for stress and weight-related disruption, and reassurance with monitoring for normal perimenopausal change. The threshold to seek care should be low. If your pregnancy test is negative and periods stay disrupted, our guide to late periods when you're not pregnant and eight reasons for missed or absent periods walk through the workup in more detail.

• ACOG: Abnormal Uterine Bleeding and Your Menstrual Cycle (FAQ)
• NHS: Irregular periods
• WHO: Family planning/contraception methods and effectiveness
• NICE CKS: Amenorrhoea
• Government of India: The Medical Termination of Pregnancy (Amendment) Act, 2021
• ICMR / Indian Thyroid Society data on thyroid disease prevalence in India