My girlfriend and I are both STD-free and she's on birth control -- how worried do I really need to be about having sex without a condom? -- Tyvon, 24, Camden, NJ

How worried you need to be depends on several things.

First, how effective is your girlfriend’s birth control method? If she has an IUD or is on the pill, you can be 99% sure she won’t get pregnant even if you don’t use a condom. But other devices, such as vaginal rings, cervical caps, or diaphragms, have lower levels of protection -—so your level of worry should rise in those cases. The other thing to think about is how certain you are of her fidelity.

If you’re very sure she isn’t likely to cheat on you, and if her method of birth control is very effective, you can probably relax and save the condoms. But if her birth control method is unreliable, or if she, herself, is unreliable, then I suggest you play it safe and stick with the raincoats.

Dr. Harry Fisch is a board certified urologist. He’s here to answer reader questions in an effort to get guys to “man up about health.”