You’ve done a test, it’s negative, and your period still hasn’t come. It’s one of the most common reasons people search “why is my period late”. The good news is that most of the time, there’s a simple explanation that has nothing to do with pregnancy.
Here are the nine most common reasons, based on NHS guidance, plus what to do next.
First, make sure the test was right
Home pregnancy tests are most reliable from the first day of a missed period. If you tested before then, a negative result might just mean it was too early. If you don’t know when your period was due, test at least 21 days after you last had unprotected sex.
If your test is negative and your period still hasn’t come, test again a few days later. The late period checker can help you work out the timing.
1. Stress
Stress is one of the most common causes of a late period. It can delay the hormone signals that trigger ovulation, and if you ovulate later, your period arrives later too. Exams, a new job, a bereavement, money worries or a break-up can all be enough.
2. Sudden weight loss
Losing a lot of weight quickly, or eating much less than your body needs, can stop your body producing the hormones needed for ovulation. Your periods may become late, irregular or stop altogether.
3. Being overweight
Being overweight can also affect the balance of hormones that control your cycle, which can make periods irregular or late.
4. Doing a lot of exercise
A big jump in training, such as preparing for a marathon, can delay or stop periods, especially if you’re not eating enough to fuel it.
5. Hormonal contraception
The combined pill, the contraceptive injection and the hormonal coil (IUS) can all make periods lighter, irregular or stop completely. That’s usually expected and harmless. After stopping hormonal contraception, it can take a while for your natural cycle to return.
6. Breastfeeding
Periods often pause or become irregular while you’re breastfeeding. Remember that you can still get pregnant during this time, even before your periods come back.
7. PCOS (now also called PMOS)
Polycystic ovary syndrome is a common hormonal condition that can cause irregular or missed periods. If a missed period comes with extra facial hair, oily skin or weight changes, that’s a reason to get checked. It can be treated, so see a GP if this sounds familiar.
8. Thyroid problems and other conditions
An overactive or underactive thyroid can change your cycle. Periods can also be affected by conditions such as diabetes and heart disease.
9. Perimenopause, or just natural variation
In the years before menopause, usually between 45 and 55, periods often become irregular. At the other end, periods are commonly irregular for the first months or years after they start, while the body settles into a pattern.
And sometimes there’s no particular cause at all. Normal cycles range from 21 to 35 days, and the length can change from one month to the next.
When to see a GP
Most late periods are nothing to worry about. But the NHS suggests seeing a GP if:
- You’ve missed three periods in a row
- Your periods have become irregular
- You’ve missed a period and also have other symptoms, such as weight gain or loss, tiredness, facial hair growth, or dry or oily skin
- Your periods haven’t started by age 15
A GP may suggest blood tests to check your hormone levels, and can talk you through treatment if a cause is found.
Get emergency help straight away if you could be pregnant and have sudden, severe tummy pain, pain in the tip of your shoulder, or feel very dizzy or faint. These can be signs of an ectopic pregnancy, even after a negative test.
Find your own pattern
One of the best ways to understand a late period is to know what’s normal for you. The period tracker learns your cycle length over time, and everything stays on your device. Read more about how late a period can be before you should worry.