In this issue of American Family Ph...

In this issue of American Family Physician, Tenore (1) provides a concisely written "how to" article upon cervical ripening and labor induction. This is timely information for family physicians practicing maternity care, considering that the prevalence of induction has nearly doubled through the past decade. Several major shifts have occurr during this period that are worth highlighting.

The Epidemiology of Induction Has Changed. The increase in the commonness of term labor induction has been well established, (2-4) to this time the change in incidence rates varies considerably from indication. Macrosomia has increased the mostly as an indication, 22.5-fold since 1980 despite evidence that induction for suspected macrosomia has shown potential benefit solitary in women with type 1 diabetes mellitus. (5 6) Post-term pregnancy, the most numerous common reason for labor induction (10 percent of live births), had and nothing else a 2.3-fold increase. At the same time, the average gestational age at delivery of post-term pregnancies declined from 419 to 410 weeks, (6) corresponding with data showing a decreased risk of stillbirth when induction is done at 41 weeks' gestation. (7) Although still controversial, induction at 41 weeks' gestation is medically justifiable. Finally, there has been a 15-fold increase in elective induction (eg no known medical indication).

Of note, induction rates have shown large variations across maternal classes, with higher induction rates being place in white, non-Hispanic women (253 percent) women with more than 12 years of education (246 percent) and women with private insurance (245 percent)2 Higher induction rates are originate in community hospital settings (increased elective inductions), compared with university or federally controll hospitals (increased inductions because of medical conditions). (8)

Elective Induction of Labor Is More habitual The rationale for elective induction is mutual convenience, allowing a pregnant woman to handle logistic issues as it is as child care and transportation, and to know that her rely uponed birth attendant will be existing for delivery. Given that chiefly induced births occur between 10 a.m. and 8 pm it is reasonable to apprehend that the physician and staff will be alert and better able to accord to an emergency. However, elective induction is not without potential risks, including iatrogenic prematurity, uterine hyperstimulation, nonreassuring fetal heart rate tracing, and greater likelihood of operative delivery, shoulder dystocia, and postpartum hemorrhage. While these complications are rare in multiparous women nulliparous women have significantly higher rates of cesarean delivery, instrumented delivery, epidural analgesia, and neonatal intensive care unit admission. (9 10) Because the risk of cesarean delivery with elective induction is potentially as high as 28 times that for spontaneous labor, it is difficult to advocate elective induction in a nulliparous woman. (10-12)

Indicators of Induction Succes Have Been Refined. Bishop's original cervical scoring theory from 1964 demonstrated that the succes of induction is related to the state of the cervix, and his work continues to influence the practice of labor care today. (13) Since Bishop's work, others have demonstrated that the most numerous important predictor of success is cervical dilation. Effacement, station, and consistency each have about individual half the effect, and position has little general intent at all. (14)

It is important to note that Bishop's research center upon elective induction, with a consideration population that included only multiparous white women at 36 weeks' gestation or more, with a crown presentation and normal obstetric history. No as it is scoring system has been validated in nulliparous women a population known to have higher rates of induction failure and posterior cesarean delivery. (9)

Newer predictors of induction succes are emerging. Transvaginal ultrasonography imprisons promise but, to date, has not been shown to outperform digital examination and cervical scoring. (15 16) Fetal fibronectin, initially studied as a way of predicting preterm labor, has been evaluated in relation to induction succes Women with fetal fibronectin in their cervicovaginal secretions had a better cervical rejoinder to prostaglandins, required fewer doses for induction of labor, and experienced a shorter time from induction to delivery. (17)

Pharmacologic Agents Have Revolutionized Cervical Ripening. The literature is filled with reports of safe and effective use of prostaglandin preparations for cervical ripening. (18-21) Dinoprostone (Cervidil) and misoprostol (Cytotec) lead the list, to this time their similarities seem to stop at the fact that they are the one and the other prostaglandins. Dinoprostone, approved for single-dose ripening, was shown to be les effective than other prostaglandins in comparative trials. (22 23) It is remov more easily than misoprostol, making it preferable in managing hyperstimulation.

Misoprostol, forward the other hand, is inexpensive, stable, and more easily stored than dinoprostone preparations. The soft cost (less than $1 by dose) offers an economic advantage from one side of to the other dinoprostone, which ranges from $150 to $200 through dose. Numerous prospective, randomized clinical trials have demonstrated the efficacy of misoprostol for cervical ripening and labor induction in time pregnancy. (18, 20, 21, 24 25) Maternal and neonatal issues have not been shown to be significantly different, despite higher rates of uterine contraction abnormalities with misoprostol use. However, misoprostol is not approved from the U.S. Food and physic Administration for cervical ripening and induction, and patients should be informed of this before it is used.