"I had sex last night, and then my period started, I was so embarrassed". Actually don't be! This is a natural thing, however having sex does not start your period. That's the good news! So you can continue to have sex! During the luteal phase, depending on how long a woman's is, at the end of it- your uterine lining will start little by little shed slowly, as your progesterone drops- and your estrogen becomes the dominate hormone. While the lining is starting to shed, it hasn't made it's way to the cervix yet, and your cervix hasn't opened. When you have sex, and orgasm, your cervix will dilate (open), and your uterus will contract. Thus
causing the menstrual blood to move down a lot faster- while it didn't start your period- it just caused the blood to move quicker.
When a woman is ready or close to starting her menstruation her cervix will become low and start to "drop". Then when she orgasms her cervix will dilate causing a "vacuum" to pull the menstrual blood down. While this can be sort of an annoyance to some women. Some women think, that sex can cause a cycle to start, if it could, most women who suffer from amenorrhea would use this "method" to start the shedding of the lining. At this time the comments for this post have been closed. Please feel free to email your questions to us at firstname.lastname@example.org, and our advocates will be glad to help you.