I found this (see link in post) about "Menstrual cycles and sea sponges"

A lady is asking a guy about it, but I do not believe THAT fact 'contaminates' his answer.

It appears from a quote at the link that there is cause for concern about using this method.
"Your concern about ocean pollution making sea sponges potentially dangerous is justified. In fact, this is the reason sea sponges are technically no longer allowed to be sold as menstrual products. In late 1980, menstrual sponges sold commercially were examined by a University of Iowa laboratory and found to contain sand, grit, bacteria, and various other contaminants. Other studies have found chemical pollutants and fungi in sponges sold for menstrual use. The Centers for Disease Control have documented a least one case of toxic shock syndrome associated with the use of a sea sponge."

Inconvenience and ineffectiveness is also mentioned, "The sponges may be contaminated, need to be boiled frequently, and sometimes leak when saturated."

Um.....

Probably that's it's a very personal subject that many of us wish to not discuss.

Maybe, just maybe it's nobodies business but our own...just saying and by the lack of responses, I might be right. We manage that however we see fit.

A special Thank You to Milf Kelly. You have informed me of this that I was previously unaware. That is the purpose of my OP. As most things in life have various options avail, I figured THIS will also.
NO WORRY. I am NOT going to 'screen'  providers by asking if she is 'currently' using one of these. I certainly don't expect that she would tell me either...but if she did...by you helping me to understand this, then I would NOT be scared away from her. This may be similarily helpful to other hobbyists as well.
A lil knowledge CAN be a good thing

I also wish to thank the others that have responded (thus far).

Thank You for your insight.
Yes, this is a natural life cycle process for women. I believe that you got my intent. I am NOT trying to embarass or worse, make women ashamed of this. OTOH, I believe it is also natural for men to be curious about this, as although not happening to our own bodies, it can pertain/limit some activities that we can do together with you ladies.

Re: ur point 3. Reminded me of a civvie GF that took birth control. We had Bareback which was great. But I was concerned about the bit that I had heard (general knowledge) about side effects, so I offered that she could quit and I'd use condoms. She kept taking them though, but I did offer.