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Initiation of Labor

  • Luis A. Cibils
  • Mary Campau Ryerson

Abstract

The extraordinary hormonal and physical changes that occur in the pregnant subject and her uterus are the ultimate expression of the wonders of adaptation. Pregnancy brings a complete turnabout of the hormonal status of the individual with the appearance of the placenta, a new, large, and potent endocrine organ that secretes a number of new hormones and metabolizes others produced by the patient or her conceptus. In addition, the physical changes of a growing uterus—a potent, contractile, hollow viscus receiving a large proportion of the cardiac output to supply the enlarged vascular bed (IVS)—constitute constant threats to interruption of the growing conceptus. Why pregnancy terminates at a given stage, and what triggers labor are fundamental biologic problems that, so far, have not been solved (an equally monumental problem, possibly closely related, is why the conceptus—a partial homograft—is not rejected by the maternal organism).

Keywords

Sarcoplasmic Reticulum Fetal Membrane Oxytocin Receptor Spontaneous Labor Uterine Activity 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© John Wright PSG · Inc. 1981

Authors and Affiliations

  • Luis A. Cibils
    • 1
  • Mary Campau Ryerson
    • 1
  1. 1.Department of Obstetrics and Gynecology The Chicago Lying-In HospitalThe University of ChicagoUSA

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