Your pelvic floor is the group of muscles that supports your bladder, womb and bowel. It's also what holds a menstrual cup in place. So whether your pelvic floor is strong, tight or weaker than it used to be, it changes how a cup feels and which size suits you. Here's what to know, including what to do if you have a prolapse.
Quick answer: Yes, most people can use a menstrual cup whatever their pelvic floor is like, but the size matters. With a strong or tight pelvic floor, the softer Lunette Size 1 avoids pressure. With a weaker pelvic floor the cup may slip down or leak, so pelvic floor exercises help. If you have, or think you have, a prolapse, talk to your doctor before using a cup.
How does your pelvic floor hold a menstrual cup?
A menstrual cup sits inside your vagina. Once it opens, it forms a light seal against the vaginal walls, and your pelvic floor muscles hold it in position. That's why the same cup can feel perfect for one person and like pressure for another: the muscles around it are different.
There's a bonus, too. Because your pelvic floor actively holds the cup, wearing one gives those muscles a little everyday training.
Menstrual cup with a strong or tight pelvic floor
If you do a lot of sport, yoga, pilates or dance, or your muscles are naturally tight, a wider, firmer cup can press against the vaginal walls or towards your bladder.
- Choose the softer cup. Lunette recommends Size 1 for strong or tight pelvic floor muscles. It's made of softer silicone and is slightly smaller (41 mm across, against 46 mm for Size 2), so it adapts to your body.
- Sensitive bladder? Size 1 is also the better choice if the cup feels like it's pressing on your bladder when you sit or move.
- Relax to remove it. Tight muscles can make removal harder. Take a breath, relax and gently bear down to bring the cup lower before you pinch the base.
Menstrual cup with a weak pelvic floor
A weaker pelvic floor is common after pregnancy and childbirth and as you get older. With a weaker pelvic floor:
- the cup may move inside the vagina or slip down, and
- it may start to leak.
What helps:
- Check the fit. If the cup keeps sliding down, look again at your size. Childbirth can also change your cervix position and flow; see wearing a menstrual cup after pregnancy.
- Do pelvic floor exercises. Lunette recommends Kegel exercises, especially if you've given birth recently or more than once.
- Back it up while you learn. Wear period underwear as a back-up on heavy days.
- Look at other leak causes. A cup that hasn't fully opened leaks too. Read why your menstrual cup might be leaking.
How to do pelvic floor exercises
The NHS describes the basic exercise like this:
- Find the muscles: imagine stopping yourself peeing and passing wind.
- Squeeze them quickly, without pulling your tummy in.
- Hold the squeeze for 2 seconds, then relax.
- Repeat 10 times. Breathe normally.
- Over time, build up to holding each squeeze for 10 seconds.
Do them every day. You may need to keep going for a few months before you notice a difference.
Can you use a menstrual cup with a prolapse?
Pelvic organ prolapse is when the womb, bladder or bowel bulges into the vagina. According to the NHS, it can happen when the pelvic floor muscles weaken. It's more common after the menopause and can be linked to pregnancy and childbirth, long-term constipation and straining, persistent coughing or pelvic surgery.
Whether a cup suits you depends on the type and severity of your prolapse, so this is a question for your doctor or a women's health physiotherapist, not for a size chart. A few things to know:
- Ask before you try. Tell your doctor you'd like to use a menstrual cup. If you use a vaginal support pessary, ask whether a cup can be used alongside it.
- A cup isn't a treatment. Treatment for prolapse can include pelvic floor muscle training, a pessary, hormone treatment or surgery.
- Stop if it hurts. If a cup causes pain, remove it and get advice.
When to see a doctor
The NHS advises seeing a GP if you have:
- a feeling of heaviness, discomfort or pressure in your lower tummy or vagina,
- a bulge or lump inside, or coming out of, your vagina,
- pain, discomfort or numbness during sex,
- problems peeing or pooing, such as leaking a little pee when you cough, sneeze or exercise.
These can be signs of a prolapse. They're also reasons to stop and get advice before using a cup again.
Which Lunette size fits your pelvic floor?
| Your pelvic floor | Usually the better fit |
|---|---|
| Strong or tight (sport, yoga, pilates) | Size 1: softer, 25 ml |
| Sensitive bladder | Size 1: softer, adapts to your body |
| Weaker, cup slips or leaks | Check your size, start pelvic floor exercises, add a back-up |
| Prolapse | Ask your doctor first |
Not sure which size you need? Our menstrual cup size guide compares both, or start with the Lunette menstrual cup in Size 1.
Pelvic floor and menstrual cups: frequently asked questions
Can a menstrual cup be used with a weak pelvic floor?
Usually, yes. A weaker pelvic floor holds the cup less firmly, so it may move, slip down or leak. Daily pelvic floor exercises help, and wearing a cup trains the muscles too. If you also feel heaviness, a bulge or pressure in your vagina, see a doctor before using a cup.
Which menstrual cup is best for a strong pelvic floor?
A softer cup. Lunette recommends Size 1 for strong or tight pelvic floor muscles, because the firmer Size 2 can cause a feeling of pressure. Size 1 is made of softer silicone and is 41 mm across, so it adapts more easily to strong muscles.
Can I use a menstrual cup if I have a prolapse?
Ask your doctor or a women's health physiotherapist first. Whether a cup is suitable depends on the type and severity of the prolapse, and on whether you use a pessary. A cup is not a treatment for prolapse. If a cup causes pain, remove it.
Does using a menstrual cup strengthen the pelvic floor?
Your pelvic floor muscles actively hold the cup in place, so wearing one gives them light everyday work. It doesn't replace pelvic floor exercises, though. For real strength, do short and long squeezes every day for a few months.
Why does my menstrual cup slip down?
A cup can slip down if your pelvic floor is weaker, if it isn't fully open, or if your cervix sits low during your period. Check that the cup has opened, look again at your size, and add pelvic floor exercises. Period underwear is a good back-up while you sort it out.
Sources
- NHS: Pelvic organ prolapse (page last reviewed 3 July 2025)
- NHS: 10 ways to stop leaks (pelvic floor exercises)
This article is for general information and isn't medical advice. If you have symptoms, talk to your doctor.
