Induction of labor at 41 weeks of pregnancy among primiparas with an unfavorable Bishop score.

Objective: To determine the rate and factors associated with the successful Induction of Labor (IOL) in nulliparous patients undergoing scheduled IOL at 41 weeks of gestational age (GA) with an unfavorable cervix.

Design: This was a retrospective analysis that included nulliparous patients who presented to the Labor and Delivery unit at the Bronx Lebanon Hospital Center between 2011 and 2012 for elective IOL at 41 weeks of GA. The Bishop score was assessed upon admission and IOL agents were used in compliance with ACOG guidelines in different combinations, based on the obstetrical team preference.

Setting: Labor and Delivery Unit of the Bronx Lebanon Hospital.

Population: Nulliparous patients with 41 weeks of pregnancy for elective induction of labor.

Sample: Seventy-six patients were included in the study. GA was confirmed using a combination of the last menstrual period and a dating sonogram during pregnancy.

Methods: This was a retrospective chart review that included nulliparous patients who presented to the Labor and Delivery unit at the Bronx Lebanon Hospital Center between October 2011 and October 2012 for elective IOL at 41 weeks of gestational age with an unfavorable cervix defined as a Bishop score of 6 or less.

Main Outcome Measures: The overall successful rate of IOL in a combination of different maternal factors with different agents for induction in nulliparous patients undergoing scheduled IOL with an unfavorable Bishop score at 41 weeks of GA was 51.32 %.

Results: Factors associated with successful IOL were younger age [22.3 years vs. 25.1(p = 0.015)], lower BMI [25 vs. 28.1(p = 0.46)] and lower maternal weight [64.75 kg vs. 74.02 (p = 0.28)]. Maternal height was not a contributing factor; the artificial rupture of membranes, epidural anesthesia and the prostaglandins used did not contribute. Use of cervical balloon and oxytocin was associated with failed IOL.

Conclusions: Patients undergoing IOL at 41 weeks with an unfavorable cervix had a successful rate of 51.32 %. Younger maternal age, lower weight, and lower BMI were associated with successful IOL.