Why may I have missed my period?

Missing your period can be worrying for many women, especially if they do not know why this may be happening. Although it can be quite common to miss a period once or twice, if you notice that periods have stopped for a time of three or more months, we recommend seeing a GP for further investigations.

Amenorrhea is the absence of menstruation, often defined as the absence of one or more menstrual periods.

Primary amenorrhea is the absence of menstruation in a person who has not menstruated until the age of 15. Common causes of primary amenorrhea are related to hormone levels.

Secondary amenorrhea is the absence of three or more periods at a time, in a person who has previously menstruated. The most common cause of secondary amenorrhea is pregnancy, though it can also occur due to hormonal imbalances.

Hormones such as oestrogen and progesterone are key in stimulating ovulation. If there are issues with the levels of these hormones, a woman will have trouble ovulating and her period will stop.

Keep in mind that this blog is not aimed at women who take birth control pills or receive hormone injections to stop their monthly bleeding with intention. If women stop taking these forms of contraception, it can take a while for their monthly period to return.

Here are 7 reasons why your period may have stopped:

Pregnancy: You might be pregnant if you’re sexually active and your period is late. Pregnancy is a common reason why periods stop. It can sometimes happen if the contraception you’re using fails. It might be that your period is simply late, so you could wait a few days to see if it arrives. If it does not arrive, you can do a pregnancy test to confirm whether or not you are pregnant. It’s important to be aware that you can still get pregnant in the days after your period is normally due. This can happen if the release of an egg (ovulation) is delayed – for example, as a result of illness or stress.
Stress: If you’re stressed, your menstrual cycle can become longer or shorter, your periods may stop altogether, or they might become more painful. The body may not produce enough oestrogen to stimulate ovulation. Try to work on managing stress by practicing mindfulness and relaxation techniques. Regular exercise, such as cycling, swimming and yoga, may help you relax. Breathing exercises can also help or using mindfulness videos. If you’re finding it hard to cope with stress, cognitive behavioural therapy (CBT) may be recommended. CBT is a talking therapy that can help you manage your problems by changing the way you think and act.
Sudden weight loss: Weight loss that is rapid and/or excessive can lead to periods stopping. Severely restricting calorie intake will impact sex hormone production, leading to ovulation stopping. If you believe this is the case, we strongly recommend you reach out to your GP as soon as possible. Your GP may refer you to a dietitian if you’re underweight. A dietitian will be able to advise you about how to regain weight safely and in a healthy way. If your weight loss is caused by an eating disorder, such as anorexia, they may refer you to an eating disorder specialist or team of specialists. Suffering from an eating disorder may also bring the risk of over-exercising.
Doing too much exercise: Overexercising, especially at higher physical intensity, can cause more stress on the body. This can influence the levels of oestrogen and progesterone in the body, which directly are linked to getting a period. High stress hormones will also impact ovulation. If someone struggles with this, they may be advised to reduce their level of activity if excessive exercise has caused their periods to stop. If someone is a professional athlete, they would benefit from seeing a doctor who specialises in sports medicine. They’ll be able to give tailored advice about how to maintain performance without disrupting periods.
Being overweight: If you are overweight, this can lead to a higher level of oestrogen being produced, as oestrogen is stored in the body’s fat tissues. Oestrogen influences the reproductive system in women, leading to periods stopping. Speaking to your GP is important for a referral to a dietitian, but we also recommend reaching out to our expert team of registered dietitians here, for quick 1-1 support on how best to help reduce the weight to help with ovulation and regaining your period.
Menopause: Menopause is defined as when periods stop completely after at least 12 months. This usually happens once a woman is in her late 40’s to early 50’s, however, there are reasons for women to go into much earlier menopause or later in their 60’s. Before menopause, there is a stage known as perimenopause. As oestrogen levels start to decrease, ovulation becomes less regular. The perimenopausal stage can last for around 4-8 years, and during this time, periods will become more irregular, often along with unpleasant side effects such as hot flushes and mood swings.
Polycystic Ovarian Syndrome (PCOS): PCOS is a common condition, affecting 10% of woman in the UK. One characteristic that women with PCOS may have, is underdeveloped follicles on their ovaries. These sacs will be unable to release an egg, preventing ovulation. It is common for women with PCOS to have infrequent or absent periods. There is no treatment for PCOS, but symptoms can be managed and there are certain medications that may be prescribed to help stimulate the monthly release of an egg from the ovaries.

If you have missed your period and are concerned, we strongly recommend reaching out to your GP for further investigations as a first line of call. You may be referred to a registered dietitian, which is where our team of experts will be on hand to help you going forward – do not hesitate to get in touch!

Written by Blanca, dietetic student intern.

Reviewed by Reema Patel, Registered Dietitian