Missed or Irregular Periods

You may assume that a missed period always means pregnancy, or that irregular periods are harmless whenever they occur during puberty or perimenopause. Pregnancy is an important first possibility, but cycle changes can also reflect contraception, stress, changes in nutrition or exercise, polycystic ovarian syndrome, thyroid or prolactin problems, chronic illness or early loss of ovarian function.

One late period is common A period may arrive earlier or later than expected without indicating disease. Temporary changes can occur with stress, travel, acute illness, sleep disruption, changes in activity, weight change, contraception, breastfeeding, or perimenopause. The importance increases when the change persists, repeats or is accompanied by other symptoms. Irregular periods describe changing cycle intervals Periods are described as irregular when the gap between them is shorter than 21 days or longer than 35 days. Irregularity may also include widely changing intervals, prolonged gaps, unpredictable bleeding, periods that stop and restart, or fewer cycles than expected over a year. Cycle variation is more common during the first years after periods begin and during perimenopause. Amenorrhoea means periods are absent Amenorrhoea means menstrual periods have not started or have stopped. Primary amenorrhoea means the first period has not occurred by the expected age. Secondary amenorrhoea means periods that previously occurred have stopped. Assessment is advised if periods have not started by age 15 or if three periods have been missed in a row. Pregnancy is the first possibility to check If pregnancy is biologically possible, take a pregnancy test even when contraception is being used, you have PCOS, you are breastfeeding, you are approaching menopause, your periods were already irregular, or you had bleeding that looked like a light period. No contraceptive method is completely effective, and irregular cycles make conception timing less predictable. A negative result taken very early may need repeating according to the test instructions. A positive test with pain or bleeding needs prompt assessment Pregnancy accompanied by pelvic pain or vaginal bleeding may represent an early viable pregnancy, miscarriage, ectopic pregnancy, or another pregnancy related complication. Ectopic pregnancy may cause one sided pelvic or abdominal pain, vaginal bleeding or brown watery discharge, shoulder tip pain, pain when passing urine or opening your bowels, dizziness, faintness, or collapse. Call 999 for severe pain, shoulder tip pain with collapse, marked dizziness or signs of internal bleeding. Seek urgent early pregnancy advice for milder pain or bleeding. Contraception commonly changes bleeding Hormonal contraception can make periods lighter, less frequent, irregular, absent, or more prolonged during adjustment. This can occur with combined hormonal contraception, progestogen only pills, implants, injections, or hormonal intrauterine systems. Absence of bleeding while using a suitable hormonal method does not necessarily mean that blood is building up inside the body. However, pregnancy testing may still be appropriate when doses were missed, medicines interfered with contraception or pregnancy symptoms occur. After emergency contraception, the next period may be earlier, later or different from usual. Take a pregnancy test according to the advice provided, particularly when the next period is substantially late, bleeding is unusually light, pregnancy symptoms develop, or pelvic pain occurs. Severe one sided pain still requires ectopic pregnancy assessment regardless of emergency contraception use. Puberty brings natural variation, but limits remain Periods often take time to establish a regular pattern after they first begin. However, assessment is needed when the first period has not occurred by age 15, periods stop for several months, bleeding is very heavy, there is severe pelvic pain. Growth or puberty appears delayed, there are symptoms of an eating disorder, there is marked weight loss, excess facial hair or severe acne develops, or pregnancy is possible. A young person should be given opportunities to discuss pregnancy, sexual health, exercise and eating privately and without judgement. Stress and low energy availability can affect periods Psychological stress can alter signals between the brain and ovaries, leading to a late period, missed cycles, reduced or absent ovulation, or changes in flow. Stress should not be assumed without considering pregnancy and physical causes. Persistent amenorrhoea deserves assessment even when stress appears relevant. Your reproductive hormone system may reduce activity when energy intake is insufficient for the demands placed on your body. Possible contributing factors include rapid weight loss, restrictive eating, an eating disorder, high exercise volume, heavy training without adequate nutrition, chronic illness, or significant emotional stress. Other signs may include fatigue, feeling cold, recurrent injuries, reduced athletic performance, low mood, low libido, or stress fractures. Prolonged low oestrogen can affect bone health. The response should address nutrition, psychological wellbeing and exercise load rather than simply prescribing hormones without understanding the cause. Higher weight can also affect ovulation Insulin resistance and hormonal changes associated with higher weight can contribute to irregular ovulation. Weight is one part of the clinical picture, not a diagnosis or a measure of effort. Care should focus on symptoms, metabolic health, goals and appropriate support rather than stigma. PCOS can cause infrequent or irregular periods Polycystic ovarian syndrome, also called PCOS, may involve irregular or absent periods, increased facial or body hair, acne or oily skin, scalp hair thinning, difficulty becoming pregnant, weight gain or difficulty losing weight, or darkened skin in body folds. Not everyone has every feature, and an ultrasound appearance alone does not diagnose PCOS. GP review is advised when irregular periods occur with weight change, tiredness, increased facial hair or skin changes. Long gaps may affect the womb lining When ovulation occurs infrequently, the womb lining may be exposed to oestrogen without regular progesterone related shedding. Over time, very infrequent periods can increase the risk of excessive thickening of the womb lining in some people. Management may therefore include treatment to regulate bleeding, protect the womb lining, provide contraception, or support fertility goals, depending on the cause and your preferences. Thyroid disease can alter periods Both underactive and overactive thyroid disease may change cycle timing or flow. Underactive thyroid may cause tiredness, feeling cold, constipation, dry skin, weight gain, or slower thinking. Overactive thyroid may cause heat intolerance, tremor, palpitations, weight loss, anxiety, or frequent bowel movements. Thyroid testing is selected when what the person describes suggests thyroid disease rather than being required for every slightly irregular cycle. High prolactin can suppress periods Prolactin is a hormone involved in milk production. Higher levels outside pregnancy and breastfeeding may cause missed or irregular periods, milk like nipple discharge, reduced libido, fertility problems, headache, or visual symptoms in some pituitary conditions. Medicines, stress, pregnancy, thyroid disease and pituitary disorders can affect prolactin. Tell the clinician about all regular and non prescription medicines. Chronic illness can disrupt cycles Periods may change with poorly controlled diabetes, coeliac disease, inflammatory illness, kidney or liver disease, severe infection, cancer treatment, or major surgery. A missed period can be one sign that the body is under physiological stress. Breastfeeding commonly delays periods Breastfeeding can suppress ovulation and delay the return of periods. However, ovulation may return before the first period, pregnancy remains possible, and bleeding patterns can be irregular as cycles restart. Breastfeeding alone is reliable contraception only under specific conditions and for a limited period. Seek contraceptive advice rather than assuming pregnancy cannot occur. Perimenopause often begins with cycle change One of the first signs of perimenopause may be periods that become more frequent, less frequent, heavier, lighter, or irregular. Other symptoms may include hot flushes, night sweats, sleep disturbance, mood change, vaginal dryness and cognitive symptoms. In people aged over 45 with a typical pattern, diagnosis is often based on symptoms rather than routine hormone testing. Pregnancy remains possible until menopause is established. Periods stopping before 45 need assessment Early menopause occurs before age 45. Premature ovarian insufficiency refers to loss or marked reduction of ovarian function before age 40. Possible symptoms include irregular or absent periods, hot flushes, night sweats, vaginal dryness, reduced fertility, or sleep disturbance. Assessment matters because reduced oestrogen at a younger age can affect bone and cardiovascular health. Treatment may be recommended unless contraindicated. Pregnancy after a missed period is not always wanted or expected You should be offered confidential, non directive information about your options. The consultation should not assume you want to continue the pregnancy, you want an abortion, the pregnancy is planned, a partner should be informed, or your feelings will be straightforward. Immediate safety and your autonomous decision making remain central. Assessment and testing Your clinician may ask when your last period was, what your previous cycle pattern was, whether you could be pregnant, which contraception you use, whether you have recently given birth or breastfed, whether your weight, eating or exercise has changed. Whether there are hot flushes or vaginal dryness, whether there is increased facial hair or acne, whether there is nipple discharge, whether there are headaches or visual changes, whether you are trying to become pregnant, and which medicines you take. Possible investigations include pregnancy test, thyroid function, prolactin, FSH in selected age groups, androgen related tests, blood glucose or metabolic assessment, pelvic ultrasound, or further specialist endocrine or gynaecological tests. A single hormone level may fluctuate and should not be interpreted without context. Management may focus on treating pregnancy related conditions, adjusting contraception, restoring adequate nutrition, modifying excessive exercise safely, managing PCOS symptoms and womb lining protection, treating thyroid or prolactin disorders, supporting fertility, replacing hormones in early ovarian insufficiency, or managing perimenopausal symptoms. A regular monthly bleed is not always required, but prolonged absence should have an understood and appropriately managed cause.

A missed or irregular period is assessed by asking whether you could be pregnant, whether this is a temporary variation or an established change, whether hormones are being altered by contraception, illness, stress, weight or exercise, whether there are other symptoms pointing towards a particular endocrine or gynaecological condition, and whether prolonged absence of periods is affecting your bones, fertility or womb lining. The aim is to identify the context rather than diagnosing from one late cycle.