Late Period: Why It Happens and What to Do

• A period is "late" when it is more than 7 days past your usual cycle length; an occasional late cycle is normal.
• Pregnancy is always the first thing to rule out for any sexually active woman, even on contraception.
• PCOS is the single most common cause of irregular or late periods in Indian women of reproductive age.
• Thyroid disease, high prolactin, stress, weight change, intense exercise and hormonal contraception are other common causes.
• See a gynaecologist if you have no period for 3 months (after regular cycles) or 6 months, or with severe pain or heavy bleeding.

The first step is knowing what is genuinely late versus what is normal cycle-to-cycle variation.

Normal cycle length. A normal menstrual cycle runs from 21 to 35 days, counting from the first day of one period to the first day of the next, with an average of around 28 days. Cycle length differs from woman to woman, and the same woman can vary by a few days each cycle without anything being wrong. The follicular phase (period to ovulation) is the variable part; the luteal phase (ovulation to the next period) is relatively fixed at 12 to 14 days. If you want a refresher on this timing, see what ovulation actually means.

What counts as late. A period is considered late if it is more than 7 days later than expected for your typical cycle. So if your usual cycle is 28 days and you are on day 36 with no period, you are about a day late; at day 42 you are clearly two weeks late and worth investigating, mainly to rule out pregnancy.

What counts as amenorrhoea. Primary amenorrhoea is no first period (menarche) by age 15 with normal secondary sexual characteristics, or by age 13 without them. This needs specialist evaluation. Secondary amenorrhoea is the absence of periods for 3 months in a woman who previously cycled regularly, or 6 months in any woman who has menstruated before. Secondary amenorrhoea warrants a gynaecology review regardless of pregnancy status.

Oligomenorrhoea (infrequent periods). Cycles longer than 35 days, with periods still arriving every 6 to 8 weeks or every few months, are called oligomenorrhoea. In Indian women of reproductive age the most common cause is PCOS. Other causes overlap with the late-period list below.

Variation versus a real problem. Stress, travel, illness, poor sleep and intense exercise can all shift a single cycle by a week or two without meaning anything is wrong. One late period with no other symptoms is usually normal variation. Repeated late or missed periods over several months are more likely to have an underlying cause that deserves evaluation — see what irregular periods can mean.

The first question for any sexually active woman. Could you be pregnant? This comes first regardless of contraception (no method is 100 per cent effective) and regardless of other possible explanations. A home pregnancy test is the first investigation; see home pregnancy test for exactly when and how to test.

For any sexually active woman of reproductive age with a late period, pregnancy is the first thing to check — whatever contraception you use.

When pregnancy is most likely. If you had unprotected sex, or used contraception imperfectly, around the time of your last ovulation, pregnancy is a realistic explanation for the missed period. If you used your method correctly throughout the cycle (perfect-use combined pills, hormonal IUS, implant, copper IUD), pregnancy is much less likely — but never impossible.

Home pregnancy test. Urine tests detect human chorionic gonadotropin (hCG), made by the developing placenta from very early in pregnancy. They are available at any Indian pharmacy under brands such as Prega News, i-can and Velocit for around Rs 20–100. Most detect hCG at about 25 mIU/mL, which corresponds roughly to the time of a missed period in a 28-day cycle. A negative test on the day your period is due may be a false negative; a negative test one week after the missed period is highly reliable.

How to test correctly. Follow the package instructions exactly. First morning urine has the most concentrated hCG, though tests work at any time of day. Read the result inside the stated window (usually 3 to 10 minutes) — results read later can show misleading evaporation lines. A clear test line plus a control line is positive; only the control line is negative; no control line means the test is invalid (use a fresh one).

False negatives. Testing too early is the commonest reason. Repeat in 3 to 7 days if your period still does not come. Very dilute urine, expired or badly stored tests are other causes.

False positives. These are uncommon. They can follow a very early pregnancy loss (a "chemical pregnancy"), a recent pregnancy or termination where hCG is still clearing, certain rare medical conditions, or misreading an evaporation line.

If positive. See your gynaecologist for confirmation (blood beta-hCG, dating ultrasound) and to start antenatal care, or to discuss your options. If there is pain or unusual bleeding with a positive test, get checked urgently to rule out ectopic pregnancy. Early spotting can also be normal — see implantation bleeding vs early period.

If negative. If periods still do not come within a week or two, repeat the test. If it remains negative and periods are still absent, work through the causes below and see your gynaecologist.

The blood beta-hCG. This quantitative blood test measures the actual hCG level and is more sensitive than urine tests. It can detect pregnancy a few days earlier and can track viability (hCG roughly doubles every 48 to 72 hours in early pregnancy). It is available at NABL-accredited labs (Dr Lal PathLabs, Metropolis, SRL, Thyrocare, Apollo Diagnostics) for about Rs 200–600 and is useful when urine tests are equivocal.

Polycystic ovary syndrome (PCOS) is the single most common cause of menstrual irregularity in Indian women of reproductive age. Prevalence estimates vary but are often quoted at 10 to 20 per cent of women, and PCOS remains substantially under-diagnosed in India.

What PCOS is. PCOS combines hyperandrogenism (raised male hormones), ovulation dysfunction (irregular or absent ovulation) and often polycystic ovarian morphology on ultrasound. The Rotterdam criteria (used by FOGSI, ACOG and ESHRE) require two of three features: oligo- or anovulation, clinical or biochemical hyperandrogenism (excess hair, acne, raised testosterone), and polycystic ovaries on ultrasound. PCOS and PCOD are often confused — see PCOD vs PCOS explained.

How PCOS affects periods. The ovulation problem directly causes irregular periods. Cycles tend to be longer than 35 days, with frequent missed cycles, and bleeds that can be unpredictable in timing and heaviness. Some women have only mild irregularity; others have very long cycles or no periods for months.

Other features that suggest PCOS. Excess hair on the chin, upper lip, chest or abdomen; persistent adult acne; scalp hair thinning; weight gain (especially around the abdomen); skin darkening in folds (acanthosis nigricans, a sign of insulin resistance); a family history of PCOS or type 2 diabetes; and difficulty conceiving. The excess-hair pattern is covered in hirsutism: excess facial and body hair.

Diagnosis. The workup includes a detailed history, examination (hirsutism score, BMI, acanthosis nigricans), blood tests (testosterone, DHEAS, SHBG, fasting insulin and glucose, HbA1c, lipids, LH, FSH, prolactin, TSH and free T4) and a pelvic ultrasound. Insulin resistance is central for many women — see PCOS and insulin resistance.

Managing irregular periods in PCOS. Combined hormonal contraceptives regulate cycles, lower androgens and provide contraception. Cyclical progestins (such as medroxyprogesterone acetate 10 mg daily for 10 days every 1 to 3 months) induce withdrawal bleeds for women who do not want hormonal contraception. Metformin helps in insulin-resistant PCOS. Losing 5 to 10 per cent of body weight markedly improves regularity, fertility and metabolic markers; diet is a powerful lever, as discussed in an anti-PCOS diet that actually works. For a full treatment map see PCOS treatment options in India, and for conception see PCOS fertility treatment.

Long-term considerations. PCOS raises the risk of type 2 diabetes, metabolic syndrome, and endometrial hyperplasia and cancer (from chronic anovulation with unopposed oestrogen). Women with PCOS who go many months without a period should have periodic progestin-induced withdrawal bleeds to protect the endometrium, even when not trying to conceive — see the warning signs of endometrial cancer.

Thyroid dysfunction and raised prolactin are common, easily tested and treatable causes of menstrual irregularity. Both belong in the first set of tests for a late or missed period.

Hypothyroidism. An underactive thyroid causes irregular cycles, often with heavier, longer bleeds, but also with missed periods and oligomenorrhoea. Other clues include fatigue, weight gain, cold intolerance, dry skin and hair, constipation and low mood. It is common in Indian women, usually from autoimmune (Hashimoto's) thyroiditis. Diagnosis is by TSH (high) and free T4 (low); levothyroxine (Eltroxin, Thyronorm, Thyrox, roughly Rs 20–100 a month) usually restores regular cycles within a few cycles. See hypothyroidism in Indian women.

Hyperthyroidism. An overactive thyroid causes irregular cycles, often lighter and shorter or absent. Other features include weight loss despite a good appetite, heat intolerance, tremor, anxiety and palpitations. Diagnosis is by TSH (suppressed) and free T4 (high), with treatment depending on the cause.

TSH testing. TSH is the screening test for menstrual irregularity, with a normal range of roughly 0.4 to 4.5 mIU/L. It costs about Rs 200–500 at Indian labs, and free T4 is added if TSH is abnormal. ACOG, FOGSI, NICE and the Endocrine Society all support TSH testing in this workup. Thyroid problems also affect conception — see thyroid and fertility.

Hyperprolactinaemia. Raised prolactin causes irregular cycles or amenorrhoea, often with galactorrhoea (milky nipple discharge unrelated to recent breastfeeding). Causes include a pituitary adenoma (prolactinoma), certain medications (antipsychotics, some antidepressants, metoclopramide, methyldopa, opioids), an underactive thyroid, and stress or exercise. See high prolactin: a quiet cause of missed periods and hyperprolactinaemia in women.

Prolactin testing. Serum prolactin is measured in the morning, fasting, and not after recent breast stimulation or exercise. The normal range is about 5 to 25 ng/mL for non-pregnant, non-lactating women. Mild elevation may not be pathological and is worth repeating under standard conditions; marked elevation (over 100 ng/mL) suggests a prolactinoma and warrants a pituitary MRI. The test costs about Rs 300–700.

Managing hyperprolactinaemia. A prolactinoma is treated with dopamine agonists (cabergoline or bromocriptine), which lower prolactin, shrink the tumour and restore cycles. If a medication is the cause, switching it is often enough; if hypothyroidism is the cause, treating that resolves the prolactin rise.

When to test. The initial workup for any persistent irregularity should include TSH and prolactin alongside a pregnancy test — inexpensive tests with high yield and treatable answers, as supported by FOGSI and the Endocrine Society.

Lifestyle factors — stress, weight change, intense exercise and poor sleep — are extremely common causes of menstrual irregularity, usually acting through the hypothalamic-pituitary-ovarian axis to suppress ovulation.

Stress. Acute or chronic stress (work, family, exams, bereavement, money, relationships) can delay or suppress ovulation for one or more cycles. Stress hormones (cortisol, CRH) dampen the GnRH pulses from the hypothalamus, which lowers FSH and LH and disrupts the cycle. One late period after a stressful stretch is common and not concerning if it settles on its own. Persistent stress-related amenorrhoea (functional hypothalamic amenorrhoea) deserves evaluation and stress management.

Weight loss. Significant or rapid weight loss, or a low body-fat percentage, can switch off ovulation, because body fat is needed for oestrogen production and normal hypothalamic-pituitary function. A BMI below about 18.5 is associated with amenorrhoea risk. Eating disorders commonly cause amenorrhoea and are under-recognised in Indian women; treatment restores nutrition and weight, often with psychological support.

Weight gain. Significant weight gain, especially around the abdomen, drives insulin resistance and PCOS-like irregularity, and often worsens cycles in women with underlying PCOS. Losing 5 to 10 per cent of body weight frequently restores regularity.

Intense exercise. Endurance athletes and women in weight-restricted sports can develop exercise-induced amenorrhoea. The "female athlete triad" (low energy availability, menstrual dysfunction, low bone density) is a recognised pattern; management balances training intensity with adequate fuelling.

Sleep disruption. Severe sleep disruption (shift work, jet lag, sleep disorders) can affect cycle regularity through circadian effects on hormones. Better sleep hygiene helps.

Illness and travel. A late period after a significant illness (COVID-19, dengue, typhoid, surgery) or long-distance travel across time zones is common and usually settles within a cycle or two.

Medications. Beyond hormonal contraceptives, antipsychotics (raise prolactin), some antidepressants, chemotherapy and corticosteroids can affect cycles. Review your medicines with your gynaecologist if irregularity starts with a new drug.

Managing lifestyle-related irregularity. Address the underlying factor — manage stress, restore a healthy weight if too low, lose weight gradually if too high, balance exercise with adequate eating, and protect sleep. Cycles often return within a few months. Persistent amenorrhoea despite these changes deserves further evaluation. The connection between hair, weight and mood is covered in hair, weight and mood — it's connected.

The Indian context. Indian women juggle work-family balance, joint-family dynamics and social expectations, and body weight can be a sensitive topic. An open conversation with your gynaecologist about lifestyle factors is part of good care.

Hormonal contraception is an extremely common cause of changes in bleeding, including missed periods and persistent absence of bleeds. The pattern depends on the method.

Combined hormonal contraceptives (pills, patch, ring). The "period" on these is a withdrawal bleed during the hormone-free week, not a true period, and is usually shorter and lighter. Missing one withdrawal bleed when active pills were taken correctly does not necessarily mean pregnancy; after two missed bleeds, take a pregnancy test. Some women never bleed on very low-dose pills. See birth control pills in India.

Progestogen-only pill (POP). POPs commonly cause irregular bleeding, missed periods or no periods at all — a normal pattern. If pregnancy is a concern, a urine test settles it.

Hormonal IUS (Mirena, Eloira). The hormonal IUS often causes amenorrhoea over time — around 20 per cent of users have no periods by one year, rising to about 40 per cent by five years. This is expected, not pathological. See IUD: copper vs hormonal.

DMPA (Depot Medroxyprogesterone Acetate). DMPA commonly causes amenorrhoea, and most users have no periods by one year of use.

Implant (etonogestrel). The implant commonly causes irregular bleeding, from frequent spotting to no periods, varying by individual.

Postpartum and breastfeeding. All methods can change bleeding after birth, on top of the natural delay of periods from breastfeeding — see breastfeeding and the return of periods.

After stopping contraception. Periods usually return within 1 to 3 months after stopping combined pills (occasionally up to 6 months), faster after the POP or hormonal IUS, and significantly later after DMPA — sometimes 6 to 12 months or more, because the depot effect persists. If periods have not returned within the typical window, check for pregnancy first; if not pregnant, give it time (especially after DMPA) and consider a workup if periods are absent by 6 months (non-DMPA) or 12 months (DMPA). Stopping contraception can also unmask underlying PCOS. See what happens after stopping birth control.

For women in their mid-40s and beyond, perimenopause is a common cause of late or skipped periods. For younger women with significant irregularity, premature ovarian insufficiency is an important consideration.

Perimenopause. The transition to menopause usually begins in the mid-40s, with the median age of menopause in Indian women around 46 to 49 years (somewhat earlier than the Western average of about 51). Cycles may shorten, then lengthen, then become irregular, with skipped cycles becoming more frequent. Hot flushes, night sweats, mood changes, disrupted sleep and vaginal dryness often accompany the transition. FSH rises but fluctuates, so a single value can mislead; diagnosis is mainly clinical, based on age and symptoms. See what is perimenopause.

Late perimenopause. As menopause nears, cycles skip more, with intervals of 60 days or more. The Indian Menopause Society and FOGSI confirm menopause after 12 consecutive months without a period in a woman of menopausal age, with no other cause.

Managing perimenopause. For bothersome symptoms, hormone replacement therapy (HRT) can be very effective and is supported by NAMS, the Indian Menopause Society and FOGSI. Other options include lifestyle measures, non-hormonal medications for hot flushes (SSRIs, gabapentin, clonidine) and vaginal moisturisers. For how this stage differs from menopause itself, see perimenopause vs menopause.

Contraception in perimenopause. Pregnancy is still possible until menopause is confirmed. Contraception is advised until at least 12 months after the last period (or until age 55). The differential for a missed period here includes both perimenopause and pregnancy — see pregnant or menopause?.

Premature ovarian insufficiency (POI). Loss of ovarian function before age 40 affects around 1 per cent of women. Causes include autoimmune, genetic (Turner variants, fragile X premutation), iatrogenic (chemotherapy, radiation, surgery) and idiopathic. Diagnosis requires amenorrhoea for at least 4 months under age 40, with two raised FSH levels (over 25 mIU/mL) at least 4 weeks apart, and low oestradiol. See primary ovarian insufficiency in India.

Managing POI. HRT is the standard treatment, usually continued until the typical age of natural menopause (around 50) to protect bone and heart health. Spontaneous pregnancy still occurs in about 5 to 10 per cent of women with POI; others may need donor-oocyte IVF. Psychological support matters, and endocrine and gynaecology input is appropriate.

When to consider POI. A woman under 40 with amenorrhoea for 4 or more months, particularly with hot flushes or other signs of oestrogen deficiency, should have FSH and oestradiol checked, with further testing (karyotype, fragile X premutation, adrenal and thyroid antibodies, pelvic ultrasound) as needed.

• A positive pregnancy test, for confirmation and antenatal care or to discuss options.
• No period for 3 months after previously regular cycles, or for 6 months in any woman.
• Severe abdominal pain with the missed period (possible ectopic pregnancy if pregnant, or an ovarian problem).
• Heavy or unusual bleeding when bleeding does occur.
• Other symptoms suggesting a cause — excess hair or acne, galactorrhoea, fatigue, weight change, hot flushes.

• ACOG — Abnormal Uterine Bleeding and Amenorrhea (FAQ)
• NHS — Irregular periods
• WHO — Polycystic ovary syndrome
• International Evidence-Based Guideline for the Assessment and Management of PCOS (2023, ESHRE/ASRM)
• Endocrine Society — Diagnosis and Treatment of Hyperprolactinemia
• ACOG — Primary Ovarian Insufficiency