What is the first stage of labor?

Updated: Jan 24, 2019
  • Author: Sarah Hagood Milton, MD; Chief Editor: Christine Isaacs, MD  more...
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Answer

Answer

The first stage begins with regular uterine contractions and ends with complete cervical dilatation at 10 cm. In Friedman’s landmark studies of 500 nulliparas [5] , he subdivided the first stage into an early latent phase and an ensuing active phase. The latent phase begins with mild, irregular uterine contractions that soften and shorten the cervix. The contractions become progressively more rhythmic and stronger. This is followed by the active phase of labor, which usually begins at about 3-4 cm of cervical dilation and is characterized by rapid cervical dilation and descent of the presenting fetal part. The first stage of labor ends with complete cervical dilation at 10 cm. According to Friedman, the active phase is further divided into an acceleration phase, a phase of maximum slope, and a deceleration phase.

Characteristics of the average cervical dilatation curve is known as the Friedman labor curve, and a series of definitions of labor protraction and arrest were subsequently established. [6, 7] However, subsequent data of modern obstetric population suggest that the rate of cervical dilatation is slower and the progression of labor may be significantly different from that suggested by the Friedman labor curve. [8, 9, 10]


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