When you're on your period, you're at a higher risk of STDs and pelvic infections. What's more, you're less likely to get pregnant, sure, but it's not impossible. So if you thought this was your ticket to ride, sorry -- you still gotta stay safe. Here are some of your options:   Diaphragms do double-duty as birth control devices and as menstrual cups to inhibit flow. Sometimes, diaphragms can be felt during sex, and removal can be messy. However, they are generally easy to use because your gynecologist will provide a diaphragm fit exactly to your cervical measurements.   Contraceptive sponges are foam devices soaked in spermicide that are inserted into your vagina during sex. They can prevent pregnancy and have the side benefit of absorbing flow, although they don't prevent STDs.   Male condoms will help prevent pregnancy, block STDs, and keep blood from getting on your partner's penis.    Female condoms, which will also keep your partner from coming into contact with blood while enabling more heat and sensation, are also a good form of birth control, although they will provide slightly less protection than male condoms. You can improve the effectiveness of a female condom by putting some spermicide on the closed end before you insert it into your vagina. Wear a menstrual cup for sexual play that doesn't involve intercourse. Wear a softcup for penetrative intercourse.  Avoid wearing regular menstrual cups during penetration. They are not designed to be used that way and will probably leak. However, if you just want to fool around, menstrual cups prevent leaking and allow for mess-free play including oral sex. Skip cups made of rubber because the rubbery smell and the taste of rubber in your vaginal fluid may be unpleasant for your partner. Use a silicone cup instead.  Instead softcups are specifically designed to be used during intercourse. They are shaped like a diaphragm, are very flexible, and available at most drugstores. Keep in mind that while you can have intercourse with a soft cup, it doesn't work as...

TL;DR in Chinese:
用保护措施。 带月经杯来阻止经血从阴道里流出。 记住精子一直在72小时内都可以存活。