Williams ], Short D, Dayal L, et al: Efect of early pregnancy following chemotherapy on disease relapse and fetal outcome in women treated for gestational trophoblastic neoplasia. J Reprod Med 59(5-6):248-54, 2014
Wolfberg AJ, Berkowitz RS, Goldstein DP: Postevacuation hCG levels and risk of gestational trophoblastic neoplasia in women with complete molar pregnancy. Obstet Gynecol 106(3):548,o2005
Woolas RP, Bower M, Newlands ES, et al: Influence of chemotherapy for gestational trophoblastic disease on subsequent pregnancy outcome. BJOG 105: 1032, 1998
World Health Organization Scientific Group: Gestational trophoblastic disease.
WHO Tech Rep Ser 692:1,o1983
Zhang W, Uu B, Wu J, et al: Hemoptysis as primary manifestation in three women with choriocarcinoma with pulmonary metastasis: a case series. J Med Case Rep 11(1):110,o201
Physiology of Labor
MATERNAL AND FETAL COMPARTMENTS .......... 400
SEX STEROID HORMONE ROLE . . ................ 401
PROSTAGLANDINS ROLE .......e..e......e..e. . ... 402
PHASE 1: UTERINE QUIESCENCE AND CERVICAL
SOFTENING ................... .......... ... 403
PHASE 2: PREPARATION FOR LABOR ............... 408
PHASE 3: .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411
UTEROTONINS IN PARTURITION PHASE 3 ........... 416
PHASE 4: THE PUERPERIUM ... .................. 417
From time immemorial inquiring minds have sought an explanation or the act that labour usualy ensues about 280 days after the appearance of the last menstrual perio, but thus ar no satiactory universal cause has been discovered.
-J. Whitridge Williams (1903)
The importance of labor physiology was highlighted in the irst edition of Wiliams Obstetrics, in which an entire section was devoted to the topic. Given the science at that time, those nine chapters were concerned with the mechanics of labor and delivery. However, the current understanding of labor includes a wide spectrum of preparedness even before the first regular contractions.
Labor is the last few hours of human pregnancy. It is characterized by forceful and painful uterine contractions that efect cervical dilation and cause the fetus to descend through the birth canal. Extensive preparations take place in both the uterus and cervix long before this. During the irst 36 to 38 weeks of normal gestation, the myometrium is in a preparatory yet unresponsive state. Concurrently, the cervix begins an early stage of remodeling yet maintains structural integrity. Following this prolonged uterine quiescence, a transitional phase follows during which myometrial unresponsiveness is suspended and the cervix undergoes ripening, efacement, and loss of structural cohesion.