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Labor is a topic covered in the 5-Minute Emergency Consult.

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Labor denotes the sequence of physiologic occurrences that result in a fetus being transported from the uterus through the birth canal.


  • Labor brings about changes in the cervix to allow passage of fetus through birth canal
  • Synchronous, coordinated contractions of the uterus
  • Contractions progress in magnitude, duration, and frequency to produce dilation of the cervix and ultimate delivery
  • Labor is divided into 3 stages:
    • Stage 1 (cervical stage): From onset of uterine contractions to full dilation of cervix
    • Stage 1 is further divided into latent and active phases:
      • In the latent phase, uterine contraction with little change in cervical dilation or effacement; contractions are mild, short (<45 sec), and irregular
      • This is followed by the active phase, which begins around time of cervical dilation of 3–4 cm; contractions are strong, regular (every 2–3 min), and last longer (>45 sec)
    • Stage 2: From onset of complete cervical dilation to time of delivery of infant
    • Stage 3: From time of delivery of baby to time of placental delivery
  • Total duration of labor varies with each woman
  • Generally, lengths of 1st and 2nd stages of labor are significantly longer for nulliparous woman:
    • Nulliparous: Mean length for 1st stage of labor is 14.4 hr and for 2nd stage of labor is 1 hr
    • Parous: Mean length of 1st stage of labor is 7.7 hr and for 2nd stage of labor is 0.2 hr
  • Length of 2nd stage of labor is greatly influenced by “3 Ps”:
    • Passenger (infant size and presentation)
    • Passageway (size of bony pelvis and soft tissues)
    • Powers (uterine contractions)
  • Problems with any of these 3 Ps can cause abnormal progression of labor:
    • Fetal malposition, uterine dysfunction, cephalopelvic disproportion
  • False labor (Braxton Hicks contractions):
    • Irregular, nonsynchronous contractions of uterus several weeks to days before onset of true labor, and do not cause cervical dilation


  • Premature labor occurs in 8–10% of pregnancies.
  • 30–40% of premature labor is caused by uterine, cervical, or urinary tract infections
  • Premature rupture of membranes is defined as rupture of amniotic/chorionic membranes at least 2 hr before onset of labor in patient before 37 wk gestation:
    • This occurs in only 3% of pregnancies but accounts for 30–40% of all premature births

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Rosen, Peter, et al., editors. "Labor." 5-Minute Emergency Consult, 5th ed., Lippincott Williams & Wilkins, 2016. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307235/all/Labor.
Labor. In: Rosen P, Shayne P, Barkin AZ, et al, eds. 5-Minute Emergency Consult. 5th ed. Lippincott Williams & Wilkins; 2016. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307235/all/Labor. Accessed April 22, 2019.
Labor. (2016). In Rosen, P., Shayne, P., Barkin, A. Z., Wolfe, R. E., Hayden, S. R., Barkin, R. M., & Schaider, J. J. (Eds.), 5-Minute Emergency Consult. Available from https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307235/all/Labor
Labor [Internet]. In: Rosen P, Shayne P, Barkin AZ, Wolfe RE, Hayden SR, Barkin RM, Schaider JJ, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2016. [cited 2019 April 22]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307235/all/Labor.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Labor ID - 307235 ED - Rosen,Peter, ED - Shayne,Philip, ED - Barkin,Adam Z, ED - Wolfe,Richard E, ED - Hayden,Stephen R, ED - Barkin,Roger M, ED - Schaider,Jeffrey J, BT - 5-Minute Emergency Consult UR - https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307235/all/Labor PB - Lippincott Williams & Wilkins ET - 5 DB - Emergency Central DP - Unbound Medicine ER -