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THREE STAGES OF LABOR
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A 25-year-old G1P0 patient at 38 weeks’ gestation presents to triage reporting contractions that have been increasing in strength and frequency over a 12-hour period. She does not have vaginal bleeding, leakage of fluid, or preeclampsia symptoms. She reports good fetal movement. Fetal heart rate (FHR) is reassuring. She is contracting every 2 minutes on the monitor. The cervical exam is 6 cm dilated, 50% effaced, 0 station, cephalic. What stage of labor is she in? If her labor progresses as expected, what should her cervical dilation be at the next vaginal exam (VE) in 2 hours?
Answer: She is in the active phase of the first stage of labor. Since she is a primigravida, her cervix should dilate at a minimum of 1.2 cm/hr. So, in 2 hours, she should be 8.4 cm (or 8–9 cm) dilated.
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Labor is defined as regular contractions that result in cervical change. A patient can have contractions that do not cause cervical change as well as cervical change without contractions—neither of these are “labor.” The progression of labor is illustrated in Figure 5-1.
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Duration of labor is typically shorter in the multiparous patient than in nulliparous patients.
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There are three stages of labor and two phases of stage 1.
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Labor is defined as contractions resulting in cervical change.
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The first stage of labor begins with onset of uterine contractions of sufficient frequency, intensity, and duration to result in effacement and dilation of the cervix, and ends when the cervix is completely dilated to 10 cm.
The first stage of labor consists of two phases:
Latent phase: Begins with the onset of labor and ends at approximately 4–6 cm cervical dilation.
Active phase: Rapid dilation. Begins at 4–6 cm dilation and ends at 10 cm.
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Remember the three “Ps” that affect the duration of the active phase of labor:
Power (strength and frequency of contractions)
Passenger (size of the baby)
Pelvis (size and shape of mother's pelvis)
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If progress during the active phase is slower than these figures, evaluation for adequacy of uterine contractions, fetal malposition, or cephalopelvic disproportion (CPD) should be done.
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