What Happens During the First Stage of Labor
For your baby to be born the cervix (comprised of firm muscle that forms a strong base at the bottom of the uterus) needs to stretch and soften so that it can open, or dilate, and your baby can pass out of the uterus and into the vagina. Toward the end of pregnancy, substances in your blood called prostaglandins start to soften the cervix so that it becomes more malleable. Your baby also gets into "position" to make his way out.
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While you are pregnant, your cervix is usually around 2 to 3 cm long. In late pregnancy or early labor, Braxton Hicks' practice contractions start to shorten the cervix, a process known as effacement. Most women have a cervix that has shortened to 1 cm during the very early stages of labor. This is also referred to as 50 percent effaced. As the cervix continues to shorten, the cervix is gradually drawn up by the uterus, and by the time it is 100 percent effaced, the cervix will have started to open.
Excerpted from Pregnancy Day by Day.
Copyright ©2009 Dorling Kindersley Limited.
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