How far does my penis go during sex?

Dear Need Directions,

Since first times don't come with an instruction manual (e.g., insert peg A into slot B), sexual mechanics can be exciting or just plain confusing. It’s not clear whether it’s your first time together or one or both of your first time ever having sex. In any case, brushing up on anatomy and physiology may be just the ticket for both of you and pave the way for more pleasurable experiences in the future.

When you mentioned the uvula, perhaps you meant the vulva, or outer genitals for those assigned female at birth. These visible parts include:

• The inner and outer labia (the lips surrounding the vagina)
• The tip of the clitoris 
• The clitoral hood or covering
• The opening of the urethra (where pee comes out)
• The opening of the vagina

There’s even more that’s not easily visible to the naked eye, which gets at the heart of your question. During vaginal sex (penetration), the penis goes into the vagina. The vaginal walls are made of soft tissue that molds around a penis, fingers, tampons, or other object placed there. The length of the vagina varies, but it's not "endless." The vagina stops at the cervix, a button-shaped entrance to the uterus (womb). Your penis may be "hitting" or bumping up against the cervix, which could be the source of your partner's discomfort.

Sex may be uncomfortable, especially during the first few rounds, but it doesn't have to be painful. Have you thought about slowing down or shifting gears? Would sex be more fun, and less confusing, if you spend some time getting to know the ins and outs of each other’s bodies first? When you and your girlfriend feel ready for take two, ample foreplay and lubrication can go a long way towards a more enjoyable sexual experience. For example, during arousal, the vagina will often lubricate, making penetrative sex more comfortable and it typically stretches out, which decreases the chances of "bumping into" the cervix. Also, a key component to sex is communicating before, during, and after to let each other know what does and doesn’t feel good — and it seems like you both have the beginnings of open and honest communication already. For more ways to minimize sexual discomfort and maximize pleasure, Our Bodies, Ourselves and Scarleteen may provide some enlightening reading.

If you or your girlfriend are still curious, you can talk with a health care provider about your anatomy quandaries. This may also be a great opportunity to be up-to-date with your respective sexual health check-ups, ensuring that each of your moving parts are in tip-top shape. For example, having a genital infection can result in pain and discomfort during sex. So, checking off sexually transmitted infection (STI) testing, pelvic exam, and pap test from the list (as necessary and indicated) is wise. Other reliable sources of information include a reproductive health care provider, a human sexuality text in your local bookstore, and Planned Parenthood.

As you and your girlfriend embark on a sexploration of possibility in the future, you may have questions about how your bodies work. A foundation in human biology, sexual health, and clear communication will give you a better idea of what you're, um, getting into.