COST-EFFECTIVENESS OF ELECTIVE INDUCTION OF LABOR AT 40 WEEKS: MATERNAL PREFERENCES MATTER

Purpose: Induction of labor has become an increasingly common obstetric intervention, affecting 22.4% of deliveries in 2006.  Little is known regarding how women value the process and potential outcomes of induction of labor, and as a result, this component of care has not been explicitly included in analyses of the cost-effectiveness of this intervention.  We sought to assess pregnant women’s preferences regarding induction of labor, and to use these values in calculating the cost-effectiveness of induction of labor at 40 weeks.

Method: We developed a decision analytic model comparing induction of labor at 40 weeks versus expectant management with antenatal testing until 41 weeks in nulliparas. Utilities were elicited from a diverse population of pregnant women obtaining prenatal care at the University of California, San Francisco, and San Francisco General Hospital.  Baseline probabilities and costs were derived from the literature, as well as from an analysis of the National Birth Data Set, and included an intrauterine fetal demise rate of 0.09% in the 40^th week, and a cesarean rate of 24.7% in induced patients and 21.6% in spontaneously laboring patients.

Result: In the base-case analysis, elective induction of labor improved clinical outcomes and was cost-effective at $17,527 per QALY.  When considering the impact of maternal preference, if the utility of induction of labor was reduced to the 25^th percentile, expectant management became the dominant option.   In terms of clinical outcomes, if the likelihood of spontaneous labor was less then 10%, induction was the dominant option; as long as the likelihood of spontaneous labor was less than 75%, induction remained cost effective.  In contrast, if the risk of cesarean with induction was twice as high as with expectant management, expectant management was dominant; as long as there was no more than a 30% increase in risk of cesarean, induction remained cost-effective.

Conclusion: Depending on maternal preference, elective induction of labor at 40 weeks may be a reasonable alternative in certain clinical scenarios.  High quality prospective evidence regarding neonatal and maternal clinical outcomes is needed in order to determine the optimal gestational age for induction; in addition, this analysis suggests that individual patient preference is paramount when considering the appropriate timing of this intervention.