Merck Manual

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Stages of Labor (2)
Stages of Labor (2)
Stages of Labor (2)

Active Phase

  • The cervix opens from about 1 1/2inches (4 centimeters) to the full 4 inches (10 centimeters). It thins and pulls back (effaces) until it merges with the rest of the uterus.

  • The presenting part of the baby, usually the head, begins to descend into the woman’s pelvis.

  • The woman begins to feel the urge to push as the baby descends, but she should resist it. Pushing too early may tear the cervix and wastes energy.

  • This phase averages about 5 to 7 hours in a first pregnancy and 2 to 4 hours in subsequent pregnancies.

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Labor Cervical Insufficiency