Induction of Labor Resources

The goal of induction of labor is to achieve vaginal delivery by stimulating uterine contractions before the spontaneous onset of labor. According to the National Center for Health Statistics, the overall rate of induction of labor in the United States has increased from 90 per 1,000 births in 1989 to 184 per 1,000 live births in 1997. Generally, induction of labor has merit as a therapeutic option when the benefits of expeditious delivery outweigh the risks of continuing the pregnancy. The benefits of labor induction must be weighed against the potential maternal or fetal risks associated with this procedure. The purpose of this bulletin is to review current methods for cervical ripening and induction of labor and to summarize the effectiveness of these approaches based on appropriately conducted outcomes-based research. These practice guidelines classify the indications for and contraindications to induction of labor, describe the various agents used for cervical ripening, cite methods used to induce labor and outline the requirements for the safe clinical use of the various methods of inducing labor.

More than 22% of all gravid women undergo induction of labor in the United States, and the overall rate of induction of labor in the US has more than doubled since 1990 to 225 per 1,000 live births in 2006 (1). The goal of induction of labor is to achieve vaginal delivery by stimulating uterine contractions before the spontaneous onset of labor. Generally, induction of labor has merit as a therapeutic option when the benefits of expeditious delivery outweigh the risks of continuing the pregnancy. The benefits of labor induction must be weighed against the potential maternal and fetal risks associated with this procedure (2). The purpose of this document is to review current methods for cervical ripening and induction of labor and to summarize the effectiveness of these approaches based on appropriately conducted outcomes-based research. These practice guidelines classify the indications for and contraindications to induction of labor, describe the various agents used for cervical ripening, cite methods used to induce labor and outline the requirements for the safe clinical use of the various methods of inducing labor.

BACKGROUND: Labor induction rates in the United States rose from 9.0 percent in 1989 to 20.5 percent in 2001, but reasons for the increase are poorly defined. A birth database from a region of upstate New York, including 31,352 deliveries from 1998 through 1999, was used to determine the degree of variation of labor induction rates among hospitals and practitioners.
METHODS: Total and elective labor induction rates were calculated for 16 hospitals and individual staff, and then evaluated using chi-square testing and regression.
RESULTS: Using all laboring women as the denominator, the regional labor induction rate was 20.8 percent; of these inductions, 25 percent had no apparent medical indication. Total induction rates and percent of elective inductions that were elective varied significantly among hospitals (10%-39% and 12%-55%, respectively, p<0.0001) and among practitioners within hospitals (7%-48% and 3%-76%, respectively, p<0.0001). Hospitals varied in size, risk status, and cesarean section rates, but these factors did not correlate with induction rates.
CONCLUSIONS: Labor induction rates are highly variable among and within hospitals. Delivery volume, population risk status, and differences in cesarean section rates did not explain this variation.

OBJECTIVE: To determine factors and outcomes associated with elective medical induction of labor as compared with spontaneous labor in low-risk women.
STUDY DESIGN: Using a birth certificate database including 11,849 low-risk, laboring women, univariate and multiple logistic regression was used to evaluate demographic and obstetric factors associated with elective labor induction. Low risk was defined as singleton, vertex, 37-41 weeks' gestation, no prior cesarean section, and no presenting medical/obstetric diagnoses considered indications for cesarean or induction. Adverse neonatal outcome was defined as 1- or 5-minute Apgar score < 7, neonatal intensive care unit admission or respiratory distress. Spontaneously laboring women (n = 10,608) were compared with women who underwent induced labor for no apparent medical/obstetric reason (n = 1,241). Interventions and outcomes during and after labor induction were adjusted for relevant associated variables.
RESULTS: Odds ratios for epidural anesthesia, cesarean delivery and diagnoses of nonreassuring fetal heart rate patterns were independently increased following elective induction; odds ratios for cephalopelvic disproportion, instrumental delivery and adverse neonatal outcome were not. Maternal length of stay was 0.34 days longer with induction than with spontaneous labor (p < 0.0001). Slightly more induced labors ended before midnight.
CONCLUSION: As compared with spontaneous labor, elective labor induction is independently associated with more intrapartum interventions, more cesarean deliveries and longer maternal length of stay. Neonatal outcome is unaffected.