A textbook of obstetrics . f Labor.—The following steps are to benoted : Dilatation of the cervix and descent of the breech tothe pelvic floor. This occurs very slowly, because the softbreech is an imperfect dilator of the cervix and an ineffectualirritator of reflex uterine contractions ; hence many hours maybe required for the first stage of labor. Rotation forward of theanterior hip, which is the first to encounter the resistance of thepelvic floor. Owing, however, to the insufficient resistancewhich the soft breech encounters, its rotation is imperfect. There then follows the birth of the
A textbook of obstetrics . f Labor.—The following steps are to benoted : Dilatation of the cervix and descent of the breech tothe pelvic floor. This occurs very slowly, because the softbreech is an imperfect dilator of the cervix and an ineffectualirritator of reflex uterine contractions ; hence many hours maybe required for the first stage of labor. Rotation forward of theanterior hip, which is the first to encounter the resistance of thepelvic floor. Owing, however, to the insufficient resistancewhich the soft breech encounters, its rotation is imperfect. There then follows the birth of the anterior hip, posterior hip,the thighs, and the trunk. The next and a very important stepis the engagement and descent of the shoulders in an obliquediameter of the pelvis. The anterior shoulder, first encounteringthe resistance of the pelvic floor, is turned forward under thepubic arch. Then occurs the birth of the anterior followed bythat of the posterior shoulder. The head by this time has 3«2 THE MECHANISM OF Fig. 234.—Breech presentation, right sacroposterior position.
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Keywords: ., bookcentury1800, bookdecade1890, bookidtex, booksubjectobstetrics
