When I meet a young woman in my clinic who’s been struggling with heavy periods, pelvic pain, or irregular cycles, one of the first questions I ask is: “Do you know how long your cycle is?” More often than I’d like, the answer is: “I’m not really sure.” And honestly, that’s not their fault.
A major new study published this year in Reproductive Health looked at over 383,000 women in the UK and found something that should make us all pause. More than one in five women overall couldn’t report their cycle length — but among women under 25, that figure rose to one in three.
The study, which analysed data from September 2020 to January 2025, revealed some striking patterns:
22.2%
Don’t know their cycle length
33.4%
Don’t know their cycle length
15.9%
Lowest unawareness rate
What’s particularly interesting is how awareness changes with age. Notice how awareness improves through the 20s and 30s, then dips slightly after 45 as cycles naturally become more variable approaching menopause. That pattern makes biological sense — but the gap in young women is concerning.
This new research echoes findings from the UK government’s Women’s Health Strategy survey, which asked nearly 100,000 women about their access to health information. The results were sobering and revealed that fewer than 1 in 5 women (17%) said they have enough information on menstrual wellbeing. Only 8% have enough information on gynaecological conditions like endometriosis and just 9% feel informed about the menopause.
Think about that for a moment. Menstruation is something half the population experiences for decades of their lives, yet the vast majority of
I can hear some of you thinking: “Does it really matter if I don’t know exactly when my last period started?”
Yes, it does. Here’s why:
Your menstrual cycle is often called the “fifth vital sign” — along with temperature, pulse, breathing rate, and blood pressure. Changes in your cycle can be an early indicator of:
When you come to see me with concerns, the first thing I need to know is your pattern. What’s “normal” for you? When did “abnormal” start? If you can tell me, “My cycles used to be 28 days, but for the last 6 months they’ve been 21 days and much heavier” — that’s gold. That’s diagnostic information that helps me help you.
Knowledge about your own body is power. It means you notice when something changes. It means you can advocate for yourself. It means you’re not starting from scratch when something feels wrong.
The study found that under-25s weren’t just less aware of their cycle length — they were also more likely to report cycle lengths outside the typical 21–35-day range while still describing their cycles as “regular.” There’s a disconnect here between what’s happening and what young women think is normal.
If you’re under 25 and reading this, you’re not “too young” to have period problems. You’re not “overreacting” if your periods are painful or heavy. And you’re definitely not alone in feeling like you don’t have enough information.
Start tracking. Just a note on your phone, a calendar mark, or a simple app. Note when it starts, when it ends, how heavy it is, and any pain. After a few months, you’ll have a picture of your “normal” — and that’s information that will serve you for decades.
The researchers who conducted this study made some important recommendations:
If you can’t answer these yet, that’s okay — start tracking now. If your answers concern you, or if they’ve changed, that’s a great reason to see a healthcare professional.
The government survey also found that 84% of women have experienced times when they felt not listened to by healthcare professionals. This is especially common for young women, and especially for menstrual concerns.
If you’ve had that experience — if you’ve been told “it’s just period pain” or “you’re too young to have a problem” — I’m sorry. That shouldn’t happen. Please know that there are specialists who will take you seriously. If one doctor doesn’t listen, it’s okay to seek a second opinion.
To every young woman reading this: your body is communicating with you every month. Learning to listen — to track, to notice, to understand — is one of the most powerful things you can do for your long-term health. You’re not being “obsessive” or “silly” by paying attention. You’re being informed.
And if you have questions, if something doesn’t feel right, if you just want to understand more — that’s what we’re here for. Ask the questions. We’ll listen.
— Mr Javaid Muglu, MRCOG
