Reviewed by The Wellness Team. Last reviewed October 2026.
A missed period with a negative pregnancy test is one of the most common reasons women look for medical advice, and in most cases the cause is findable and treatable. Here are the real causes, the tests that sort them out, and when it is worth booking a GP.
What counts as a missed period
A typical cycle runs between 21 and 35 days. A period is generally called missed when it is a week or more late for you, and doctors use the term amenorrhoea when periods stop for three months or more, or have not started by age 15. One late period with a negative test is usually nothing serious; three missed in a row deserves investigation.
First, rule pregnancy out properly
Home tests are reliable but not perfect. Test again a week after the missed period if the first was negative, using first morning urine. A blood test measures the pregnancy hormone precisely and settles the question when the timing is unclear, particularly after IVF, with irregular cycles, or when a test was taken too early.
The common causes of a missed period
Stress: physical or emotional stress can suppress the hormonal signal that triggers ovulation, delaying the whole cycle
Weight change: significant weight loss, low body weight or rapid weight gain can all pause ovulation
Excessive exercise: training loads that outpace calorie intake commonly stop periods
Polycystic ovary syndrome (PCOS): one of the most frequent causes of irregular or absent periods, often with acne or excess hair growth
Thyroid problems: both an overactive and an underactive thyroid disrupt cycles
Raised prolactin: the hormone that drives milk production can rise for several reasons and switch periods off
Perimenopause: cycles often become irregular from the early forties, and occasionally earlier
Coming off hormonal contraception: periods can take a few months to return after stopping the pill, injection or implant
Premature ovarian insufficiency: periods stopping before 40, sometimes with hot flushes or night sweats
The tests that find the cause
NICE guidance supports a straightforward sequence. After pregnancy is excluded, blood tests check thyroid function, prolactin and the ovarian hormones FSH and LH, with testosterone where PCOS is suspected. A pelvic ultrasound is added when the bloods point that way, for example to look for the ovarian appearance of PCOS. Most women get a clear answer from this workup, and a clear answer decides the treatment.
When to see a GP
Book an assessment if any of the following apply:
You have missed three periods in a row
Milky nipple discharge, new headaches or changes in your vision
Hot flushes, night sweats or vaginal dryness, especially under 40
New acne, excess hair growth, or hair thinning alongside irregular periods
You are trying to conceive and your cycles are unpredictable
You have lost a significant amount of weight or your training load has increased sharply
None of these means something is seriously wrong. They mean the cause is worth finding rather than guessing.
What an online GP can do today
A GP can take a proper history by video or phone, work out which of the causes above fits, and arrange the right blood tests the same day. Comprehensive panels covering thyroid, prolactin, ovarian hormones and more start at £495, with results explained to you directly rather than left as numbers on a page. Where treatment, a scan or a referral is the right next step, that is arranged too.
Appointments cost £59 by phone, £150 by video and £220 in person at 10 Portman Square, Marylebone, with the price confirmed before you book. Same day appointments are usually available. Message us on WhatsApp: https://wa.me/447961280835
Frequently asked questions
Can stress really delay a period?
Yes. Stress raises cortisol, which can suppress the hormonal signal for ovulation. When ovulation happens late, the period arrives late; when it does not happen, the period is missed entirely. It is one of the most common causes of a one off late period.
How late can a period be before I should worry?
A one off period a week or two late with a negative test is usually safe to watch. Three missed periods in a row, or a missed period with any of the symptoms listed above, is the point at which NICE aligned guidance supports investigation.
Will a missed period affect my fertility?
That depends entirely on the cause, which is why testing matters. Stress, weight and exercise related causes usually reverse. PCOS and thyroid problems are very treatable. Finding the cause early gives you the most options.
Could it be early menopause?
Cycles commonly become irregular from the early forties. Periods stopping before 40, especially with hot flushes or night sweats, need blood tests for premature ovarian insufficiency, because treatment protects bone and heart health as well as symptoms.
Sources: NICE Clinical Knowledge Summaries, Amenorrhoea; NICE guideline NG23, Menopause: identification and management.
Reviewed by The Wellness Team