Did a little self-edumacation regarding the cervix and thought I'd share. I'm certainly no gyney and most of this came from wiki. The cervix is basically the lower third of the uterus. The function of the cervix is to allow flow of menstrual blood from the uterus into the vagina, and direct sperm into the uterus during intercourse.
During orgasm, the cervix convulses and the external os dilates. Docs say that this behavior would tend to draw semen in the vagina into the uterus, increasing the likelihood of conception. This explanation has been called the "upsuck theory of female orgasm."
During menstruation the cervix stretches open slightly to allow the endometrium to be shed. This stretching is believed to be part of the cramping pain that many women experience, evidenced by the fact that some women's cramps subside or disappear after their first vaginal birth because the cervical opening has widened. Hmmmm
During childbirth, contractions of the uterus will dilate the cervix up to 10 cm (4 inches) in diameter to allow the child to pass through.
After a menstrual period ends, the external os is blocked by mucus that is thick and acidic. This "infertile" mucus blocks spermatozoa from entering the uterus. For several days around the time of ovulation, "fertile" types of mucus are produced: they have a higher water content, are less acidic, and have a ferning pattern that helps guide spermatozoa through the cervix. This ferning is a branching pattern seen in the mucus when observed with low magnification.
Cervical mucus
Most methods of hormonal contraception work primarily by preventing ovulation, but their effectiveness is increased because they prevent the fertile types of cervical mucus from being produced. Conversely, methods of thinning the mucus may help to achieve pregnancy.
During pregnancy the cervix is blocked by a special antibacterial mucosal plug which prevents infection, somewhat similar to its state during the infertile portion of the menstrual cycle. The mucus plug comes out as the cervix dilates in labor or shortly before. I assume this is when the woman's "water breaks."
So there ya go, take it for what it's worth. :mrgreen: