Vaginal Estradiol pretreatment in Labor induction with Misoprostol: Randomized Clinical Trial

Abstract

Labor is a clinical diagnosis characterized by regular, painful uterine contractions that increase in frequency and intensity is associated with progressive cervical effacement or dilatation. More specifically, it is associated with a change in the myometrial contractility pattern from irregular "contractures" (long lasting, low-frequency activity) to regular "contractions" (high-intensity, high frequency activity). The cervix consists primarily of collagen, a fibrous connective tissue that undergoes extensive remodeling and dynamic anatomic and physiologic alterations throughout pregnancy.The cervix maintains tremendous weight-bearing potential and tensile strength until gestation is complete. The cervical remodeling process occurs in four distinct endocrinologic andstructurally unique stages: softening, ripening, dilation, andpostpartum repair. Induction of labor is an obstetrical intervention to stimulate uterine contractions before spontaneous onset of labor. Induction of labor (IOL) can be obtained by two actions: cervical ripening and induction of contractions, which can be more or less combined Methods for induction of labor can be mechanical or pharmacological. Mechanical means of labor induction include the use various types of catheters and hygroscopic dilators introduced into the cervical canal or into the extra-amnioticspace. Pharmacological methods include prostaglandins, mifepristone and oxytocin.

The goals of induction of labor are to prevent anticipated poor outcomes associated with continuation of pregnancy, efficient uterine activity sufficient for cervical change and fetal descent without causing uterine hyperstimulation or fetal compromise and to allow as natural abirth experience as safely possible. Misoprostol is a prostaglandin E1 analogue, has been shown to have both safety and efficacy for cervical ripening and labor induction. Misoprostol has the advantage of being inexpensive and stable at room temperature and needs no refrigeration for its storage In most trials vaginal route has been chosen, because this route has been most successful for other prostaglandinsand because misoprostol has far longer half-life when administered vaginally than orally. However, the short half-life of misoprostol may be an advantage in induction of labor, because of the less risk for hyperstimulation of the uterus.