Why is my period late, but my pregnancy test is negative?

Reviewed: January 4, 2021
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Eight possible causes for why your period may be late when you’ve had a negative pregnancy test.

Periods…we hate to have them, but when they’re late we’re consumed with worry about why they’re not there. 

Whilst pregnancy is usually front of mind when a period is late, there can be a number of reasons why you may have a late period that aren’t because you’re pregnant. Below are eight possible causes for why your period may be late when you’ve had a negative pregnancy test.  

Possible reasons for a late period

  • Contraception method
  • Breastfeeding
  • Perimenopause
  • PCOS
  • Weight gain or weight loss
  • Stress
  • Excessive exercise
  • COVID-19?

Contraception method

The type of contraception you are using plays a factor in how your menstrual cycle operates. Contraception methods that contain hormones, in particular progesterone, are more likely to cause irregular and late or infrequent periods, with the contraceptives most likely to cause a late period being the mini pill, contraceptive implant, contraceptive injection and IUS (the hormonal coil).  Check out our contraceptive reviews to see which choice of birth control our users have experienced late periods whilst on.


If you are breastfeeding your newborn then your period may not return for many months. This happens as a result of prolactin, the hormone that causes you to make breast milk, which is the same one that stops you from ovulating and having your period.


Perimenopause is the term used for the time when a woman’s body makes the natural transition to menopause (stopping or periods altogether), from the beginning of menopausal symptoms to the after menopause. The menopause is a natural part of ageing, experienced by all women, and normally happens between the ages of 45 and 55. There can be exceptions to this and before the age of 45 is considered early menopause. When menopause occurs under the age of 40, this is known as premature menopause.

A woman’s level of oestrogen will rise and fall during this time and she may begin to have menstrual cycles where the body doesn’t release an egg. As the menopause approaches it is not uncommon to miss the occasional period and although pregnancy should be considered, it is more likely that this represents the transition into the menopause. It is normal sometimes not to get a period for two or three months, and thereafter have a heavy period which can be difficult to manage.


Polycystic Ovary Syndrome (PCOS) is a common condition that affects how a women’s ovaries work, affecting about 1 in every 10 women in the UK.

The 3 main features of PCOS are:

  • irregular periods or no periods at all  – which means your ovaries do not regularly release eggs (ovulation)
  • excess androgen – high levels of “male” hormones in your body, which may cause physical signs such as excess facial or body hair
  • polycystic ovaries – your ovaries become enlarged and contain many fluid-filled sacs (follicles) that surround the eggs

Other signs and symptoms include weight gain, thinning hair and hair loss from the head, oily skin or acne and difficulty getting pregnant as a result of irregular ovulation or failure to ovulate. Whilst the exact cause of PCOS is unknown it often runs in families and is related to abnormal hormone levels, including high levels of insulin.

Weight gain or weight loss

Whilst there is no defined amount of weight that a woman can put on or lose for it to affect her period, the more significant the gain or loss in a shorter period of time the more likely her period may be late. Excessive weight loss is more likely to cause a late period than weight gain. 


If getting your period wasn’t stressful enough, high levels of stress can actually delay your menstrual cycle. Excessive stress can affect your hormones which in turn can affect your periods. If a woman experiences severe stress they may find their periods are shorter, lighter or even non-existent. Your GP can help you explore methods that will help you manage your stress. 

Excessive exercise

When you miss your period due to excessive exercise this is known as exercise-induced amenorrhea. This can be common in female athletes. Your menstrual cycle will usually return to normal once you resume a lighter exercise routine, but there can be significant risks with long term amenorrhea, including infertility and changes in bone density.


Whilst research is still in its early days, health professionals are reporting more cases of coronavirus messing with women’s menstrual cycles. With the current pandemic qualifying as a major form of stress, it’s not surprising that women are reporting irregular menstrual cycles and late periods.

What to do when your period is late?

If you have had a negative pregnancy test and you have missed three periods in a row, or are having ongoing irregular periods then make an appointment with your GP. There are other medical causes of missed or irregular periods we’ve not mentioned here. If your GP thinks that your lack of periods may be due to a medical cause they will investigate this, and may refer you to a specialist clinic. 


Menopause Matters


NICE Clinical Knowledge Summaries

Reviewed and edited on 04/01/2021 in line with our content policy.

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