If your periods are often late, or months apart, PMOS is one of the most common explanations. It’s a hormone condition that used to be called polycystic ovary syndrome (PCOS). You’ll see both names for now. This post explains how it affects your cycle, what the other signs are, and what to do next.
Why the name changed
The NHS now calls the condition polyendocrine metabolic ovarian syndrome (PMOS). The old name, polycystic ovary syndrome, suggested that the main problem was cysts on the ovaries. In fact, many people with the condition don’t have them, and it affects hormones and metabolism throughout the body. The new name is meant to describe it more accurately.
If you were diagnosed with PCOS, nothing about your diagnosis or treatment has changed. It’s the same condition.
How PMOS makes periods late
A period usually comes around two weeks after ovulation, when an ovary releases an egg. In PMOS, hormone levels can stop the ovaries releasing an egg regularly.
When ovulation is delayed, the period is delayed too. When it doesn’t happen at all in a cycle, the period may not come. That’s why PMOS often causes:
- cycles longer than 35 days
- periods that are hard to predict from month to month
- months with no period at all
Calculators that assume ovulation happens on a set day can’t predict these cycles well. The period calculator shows date ranges rather than a single date, and the late period checker will tell you if your cycles fall outside the usual range.
Other signs of PMOS
Irregular periods are the most common sign, but the NHS lists several others:
- excess hair growth, often on the face, chest or back, or thinning hair on the head
- weight gain, or finding it hard to lose weight
- difficulty getting pregnant
- oily skin and acne
- feeling very tired
- depression or anxiety
- thick, dark patches of skin, often on the neck or in the armpits
Symptoms usually start around puberty, though many people aren’t diagnosed until later. Some people have only one or two signs, and some have none.
Having some of these symptoms doesn’t mean you have PMOS. Many are common and can have other causes. That’s why it’s worth getting them checked rather than guessing.
How it’s diagnosed
If a GP thinks you might have PMOS, they’ll ask about your periods and other symptoms. They may arrange:
- blood tests to check your hormone levels and whether you have insulin resistance
- an ultrasound scan of your ovaries, usually only if you’re over 18
They’ll also want to rule out other causes of irregular periods, such as thyroid problems. You may be referred to a gynaecologist or a hormone specialist (endocrinologist).
It helps to bring a record of your last few cycles. Even a simple list of start dates makes it much easier to see your pattern. The period tracker can turn your log into a summary to show your GP, and it stays on your own device.
What helps
There’s no cure for PMOS, but symptoms can be managed. Depending on what bothers you most, options include:
- Hormonal contraception, such as the combined pill, the progestogen-only pill or a hormonal coil (IUS), to make bleeding more regular
- Fertility medicines such as clomifene, if you’re trying to get pregnant
- Metformin, a diabetes medicine that can help with tiredness and weight
- Medicines and creams for unwanted hair growth and acne
- Weight loss support, including medicines for some people
Lifestyle changes help many people too. The NHS recommends a balanced diet, regular exercise and, if you’re overweight, losing some weight. Even modest weight loss can make periods more regular for some people. Talking therapy can help if PMOS is affecting your mood.
Why it’s worth getting checked
Long gaps between periods aren’t just inconvenient. Getting a diagnosis means you can:
- understand why your cycle behaves the way it does, so a late period is less of a worry
- get support with fertility, if and when you want it
- be checked for related health risks, such as insulin resistance
- get treatment for symptoms that affect your confidence or daily life
When to see a GP
See a GP if you think you might have PMOS, or if your symptoms are affecting your everyday life, work or relationships. The NHS also advises seeing a GP if you’ve missed three periods in a row, if your periods have become irregular, or if your periods are irregular and you’re struggling to get pregnant.
And if a period is late and there’s any chance you could be pregnant, take a pregnancy test first. Having PMOS doesn’t mean you can’t get pregnant, and irregular cycles can make it easier to miss the early signs.