---
title: "Late or Missed Period: Reasons and When to See a Doctor"
description: "Why a period can be late or missed, the common reasons, what a negative pregnancy test can mean and when to see a doctor, with NHS and ACOG sources."
url: https://periodcalc.app/late-period/
lang: en
---
# Why is my period late?

Common reasons, what a negative test can mean and when to see a doctor.

Late periods have many causes and are usually nothing to worry about, but see a doctor just in case ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)). Common causes include pregnancy and stress ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)), and most home tests work from the first day of a missed period ([NHS](https://www.nhs.uk/pregnancy/trying-for-a-baby/doing-a-pregnancy-test/)). See a doctor after 3 missed periods in a row ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)), and get help quickly for the [warning signs](https://periodcalc.app/late-period/#urgent-signs).

By [Hossam Hamouda](https://periodcalc.app/about/), developer of Period Calc · Last updated: 25 October 2026

Predictions are estimates, not medical advice or a diagnosis, and not a method of contraception.

## How late is a late period?

The NHS and ACOG pages used here do not say after how many days a period counts as late. The NHS is the UK health service, and ACOG is the American College of Obstetricians and Gynecologists. The NHS says many women have a missed or late period at some time. It says this is usually nothing to worry about, but that you should see a doctor about it just in case ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)).

Count from the first day of your last period, as explained in [how long a period and a cycle last](https://periodcalc.app/how-long-does-a-period-last/). Or let the [period calculator](https://periodcalc.app/period-calculator/) show the date you expected.

## Common reasons for a late period

If you have had sex, pregnancy comes first: you could be pregnant if you miss a period ([NHS](https://www.nhs.uk/conditions/periods/)). A bleed like a very light period around the time your period is due can be implantation bleeding, an early sign of pregnancy ([NHS](https://www.nhs.uk/pregnancy/trying-for-a-baby/signs-and-symptoms-that-might-mean-youre-pregnant/)).

These are common causes the NHS lists for a missed or late period ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)):

- stress;
- sudden weight loss, or being overweight;
- too much exercise;
- some hormonal contraception, such as the pill, the injection or an IUS (a hormone device in the womb);
- breastfeeding;
- the start of the menopause, called perimenopause, usually between the ages of 45 and 55 (the menopause is the time when periods stop for good, says [ACOG](https://www.acog.org/womens-health/faqs/amenorrhea-absence-of-periods));
- polycystic ovary syndrome (PCOS), which the NHS now calls polyendocrine metabolic ovarian syndrome (PMOS); ACOG describes it as a condition that leads to a hormone imbalance affecting periods and ovulation ([ACOG](https://www.acog.org/womens-health/faqs/amenorrhea-absence-of-periods));
- medical conditions such as heart disease, diabetes or thyroid problems.

ACOG’s list of reasons adds eating disorders and low body weight ([ACOG](https://www.acog.org/womens-health/faqs/amenorrhea-absence-of-periods)). The NHS says changing your method of contraception can also upset your cycle ([NHS](https://www.nhs.uk/conditions/periods/period-problems/)). A doctor can look for the cause, and treatment depends on it ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)).

## When to take a pregnancy test

Most home pregnancy tests work from the first day of a missed period ([NHS](https://www.nhs.uk/pregnancy/trying-for-a-baby/doing-a-pregnancy-test/)). The [pregnancy test date calculator](https://periodcalc.app/pregnancy-test-date/) shows the date your next period is due.

## My period is late and the test is negative: what now?

A negative result is less reliable than a positive one, for example if you test too early or do not follow the instructions ([NHS](https://www.nhs.uk/pregnancy/trying-for-a-baby/doing-a-pregnancy-test/)). If your test is negative and you still think you are pregnant, wait a few days and test again. If a second test is negative and your period has still not come, see a doctor ([NHS](https://www.nhs.uk/pregnancy/trying-for-a-baby/doing-a-pregnancy-test/)). The NHS also says to see a doctor if a pregnancy test is negative and you have missed 3 periods in a row ([NHS](https://www.nhs.uk/conditions/periods/)).

## When to see a doctor

- You have missed 3 periods in a row ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)), or your period has stopped for about 3 months and you cannot explain why ([ACOG](https://www.acog.org/womens-health/faqs/amenorrhea-absence-of-periods)).
- A second pregnancy test is negative and your period has still not come ([NHS](https://www.nhs.uk/pregnancy/trying-for-a-baby/doing-a-pregnancy-test/)).
- Your periods have not started by age 15 ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/), [ACOG](https://www.acog.org/womens-health/faqs/amenorrhea-absence-of-periods)).
- You have missed a period and also have weight gain or loss, tiredness, hair growth on your face, or dry or oily skin ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)).
- Your periods have become irregular ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)): see [irregular periods](https://periodcalc.app/irregular-periods/).

ACOG says that missing periods can be a sign of an underlying medical issue ([ACOG](https://www.acog.org/womens-health/faqs/amenorrhea-absence-of-periods)).

## Warning signs that need help quickly

Get medical help quickly if you have all of these ([NHS](https://www.nhs.uk/symptoms/vaginal-bleeding-between-periods-or-after-sex/)):

- you have recently missed a period;
- you have unusual vaginal bleeding;
- you have pain anywhere in your tummy, including your lower tummy (pelvic pain).

The NHS says this could be an ectopic pregnancy (a pregnancy growing outside the womb) and needs to be checked as soon as possible ([NHS](https://www.nhs.uk/symptoms/vaginal-bleeding-between-periods-or-after-sex/)).

In the UK, the NHS says to call 999 or go to A&E (accident and emergency) immediately if you have a combination of these signs ([NHS](https://www.nhs.uk/conditions/ectopic-pregnancy/)):

- a sharp, sudden and intense pain in your tummy;
- feeling very dizzy or fainting;
- feeling sick;
- looking very pale.

The NHS says these signs could mean that a fallopian tube (a tube that connects an ovary to the womb) has split open. This is very serious, but treatable if dealt with quickly ([NHS](https://www.nhs.uk/conditions/ectopic-pregnancy/)). Outside the UK, use your local emergency number. ACOG says to go to an emergency room for sudden, severe pain in your tummy or pelvis (your lower tummy), shoulder pain, or weakness ([ACOG](https://www.acog.org/womens-health/faqs/ectopic-pregnancy)).

## Getting ready for the visit

Write down the first day of your last few periods and any other symptoms. The NHS says a diary gives your doctor a detailed idea of what happens and when ([NHS](https://www.nhs.uk/conditions/periods/period-problems/)).

## Questions about a late period

### How many days late can a period be before I worry?

The NHS and ACOG pages used here do not set a number of days for ‘late’. The NHS says to see a doctor about a late period just in case, and after 3 missed periods in a row ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)). ACOG says to be checked if your period stops for about 3 months without an explanation ([ACOG](https://www.acog.org/womens-health/faqs/amenorrhea-absence-of-periods)).

### Can stress make my period late?

Yes. Stress is on the NHS list of causes of a missed or late period ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)) and on ACOG’s list of reasons why periods stop ([ACOG](https://www.acog.org/womens-health/faqs/amenorrhea-absence-of-periods)).

### Do I have to take a pregnancy test in the morning?

The NHS says a urine sample from any time of the day will do. All tests are slightly different, so check the instructions in the box ([NHS](https://www.nhs.uk/pregnancy/trying-for-a-baby/doing-a-pregnancy-test/)).

### Can a period be late if I am not pregnant?

Yes. The NHS lists many other causes, such as stress, sudden weight loss, being overweight, too much exercise, breastfeeding and the start of the menopause ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)). A doctor can look for the cause, and treatment depends on it ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)).

### Can breastfeeding or contraception delay my period?

Yes. The NHS lists breastfeeding and some hormonal contraception, such as the pill or the injection, as common causes of a missed or late period ([NHS](https://www.nhs.uk/symptoms/missed-or-late-periods/)). It also says changing your method of contraception can upset your cycle ([NHS](https://www.nhs.uk/conditions/periods/period-problems/)).

## How this page was made

Hossam Hamouda, the developer of Period Calc, wrote this page from the guidance of the NHS and ACOG pages listed under [Sources](https://periodcalc.app/late-period/#sources), and checked it against them on the date shown at the top. Those organisations have not reviewed it, and neither has a doctor. It explains what the sources say and cannot tell you why your own period is late. If something worries you, see [when to see a doctor](https://periodcalc.app/late-period/#see-a-doctor).

## Sources

1. [Missed or late periods](https://www.nhs.uk/symptoms/missed-or-late-periods/) (NHS)
2. [Periods](https://www.nhs.uk/conditions/periods/) (NHS)
3. [Period problems](https://www.nhs.uk/conditions/periods/period-problems/) (NHS)
4. [Doing a pregnancy test](https://www.nhs.uk/pregnancy/trying-for-a-baby/doing-a-pregnancy-test/) (NHS)
5. [Signs and symptoms that might mean you're pregnant](https://www.nhs.uk/pregnancy/trying-for-a-baby/signs-and-symptoms-that-might-mean-youre-pregnant/) (NHS)
6. [Vaginal bleeding between periods or after sex](https://www.nhs.uk/symptoms/vaginal-bleeding-between-periods-or-after-sex/) (NHS)
7. [Ectopic pregnancy](https://www.nhs.uk/conditions/ectopic-pregnancy/) (NHS)
8. [Amenorrhea: Absence of Periods](https://www.acog.org/womens-health/faqs/amenorrhea-absence-of-periods) (ACOG)
9. [Ectopic Pregnancy](https://www.acog.org/womens-health/faqs/ectopic-pregnancy) (ACOG)

## Get reminders before your next period

**Period Calc** for iPhone learns from your own cycles and reminds you two days before your period — discreetly, with no details unless you turn them on.

- The Hijri date on every calendar day
- Your fasting days, every month
- A PIN and Face ID lock, and no account

[Download on the App Store](https://apps.apple.com/app/id6814298894)

## Related guides

- [How long a period lasts](https://periodcalc.app/how-long-does-a-period-last/): A period usually lasts 2 to 7 days and a cycle 21 to 35 days.
- [Signs of ovulation](https://periodcalc.app/signs-of-ovulation/): Mucus, temperature, tests and pain can show ovulation, but a temperature rise only confirms it afterwards.
- [Irregular periods](https://periodcalc.app/irregular-periods/): The NHS calls periods irregular when the gap is under 21 or over 35 days, and says they are not usually a sign of a problem.

## Free calculators

- [Period calculator](https://periodcalc.app/period-calculator/): Your next six periods, fertile days and ovulation, in Gregorian and Hijri dates.
- [Ovulation calculator](https://periodcalc.app/ovulation-calculator/): Your fertile window and ovulation day for the next three cycles.
- [Due date calculator](https://periodcalc.app/due-date-calculator/): Your due date, how many weeks pregnant you are and your trimester.
- [Pregnancy week calculator](https://periodcalc.app/pregnancy-week-calculator/): How many weeks and days pregnant you are, your trimester and due date, from your last period or your due date.
- [Conception date calculator](https://periodcalc.app/conception-date-calculator/): Count back from your due date to the days you most likely conceived: an estimate, not an exact day.
- [Pregnancy test date calculator](https://periodcalc.app/pregnancy-test-date/): Shows the day your next period is due. The NHS says most tests can be done from the first day of a missed period.

Predictions are estimates, not medical advice or a diagnosis, and not a method of contraception.

The prayer & purity guide gives the general rules of the four schools. It is not a fatwa — for your own case, ask someone whose knowledge you trust.

This website uses no cookies and no analytics. The calculators run in your browser, and nothing you type is sent anywhere.