Older Bee here (over 50)
I used a Diaphragm for many years… after I had issues with the Pill following my first pregnancy.
Never had any issues with the Diaphragm as far as effectiveness… in that I NEVER had a pregnancy in my life that wasn’t planned.
That said, there is a bit of a learning curve (but then that is true of any BC)
The Diaphragm takes a bit of getting used to as far as getting it into place, and then out. When in spot it will sit snuggly up against the pubic bone, and create a vacuum seal.
You can use it with or without spermicide… (if you are one who also knows their body enough to be able to know the signs of ovulation)
Using spermicide with it is always the safest method around ovulation, … BUT it is not what you want to be enjoying with a side of oral (ick)
Which means you have to plan accordingly
I used the Diaphragm consistently EVERY time we had sex, no matter what day of the month. AND YES there is the benefit that it is essentially a cup / dish / disc that covers the cervix entirely so during one’s period, it can contain any flow… which means sex is possible all month long if you wish it to be so.
The upside to the Diaphragm is that it isn’t hormonal… nor is it invasive like an IUD (sorry, but after the horror stories of / deaths of my era I would NEVER recommend anyone look at putting copper into their womb)
You can put it into place and leave it there, for a period of time before you have sex, and then you can leave it in place for a longer period of time afterwards… you do have to remove it once every 24 hours to clean it. And if you have sex 2 or more times within the timeframe you SHOULD NOT REMOVE IT… but rather inject more spermicide into your vagina.
The downside is… if you are sensitive to Latex it won’t be a viable choice for you
Also, if you haven’t planned to have sex, you may find yourself making a mad dash to the bathroom to put the Diaphragm into place (could kill the mood)
IF you are away from home, and need to remove it, clean it that can sometimes be inconvenient (public washrooms, camping trips, etc)
And you have to go to a Dr. to be fitted / measured for it. Also, the Diaphragm altho a very reliable method, is one that is losing in popularity. So you might find it difficult to locate a place that stocks them…
That was certainly my experience the last time I was refitted.
Hope this helps,