Effect of Maternal Age and Body Mass Index on Induction of Labor Using Oral Misoprostol in Late-Term Pregnancies: A Retrospective Cross-Sectional Study

Abstract

Introduction: Several studies have shown that late- and post-term pregnancies are associated with an increased risk of perinatal morbidity and mortality. In this case, induction of labor is the recommended approach. For full-term pregnancies, various methods exist to prepare the cervix and/or commence labor. Prostaglandins serve the dual purpose of cervical ripening and labor induction, blurring the distinction between the two processes. The aim of this research was to evaluate the effect of maternal age and body mass index (BMI) on oral misoprostol induction of labor for late-term pregnancies. Methods: This was a retrospective cross-sectional study (ClinicalTrial ID: NCT06184139), including only late-term pregnancies in healthy nulliparous women carrying a single cephalic fetus with normal birthweight who underwent induction of labor with oral misoprostol. We used the oral misoprostol regimen proposed by the World Health Organization (WHO) for induction of labor in term singleton pregnancies in women who have not had a previous cesarean delivery and a Bishop score <7. The regimen was oral misoprostol in aqueous solution at the low dose of 25 μg every 2 h until a Bishop score ≥7, labor, or for a maximum of 8 doses. Results: One hundred and four pregnant women underwent induction of labor with oral misoprostol for late-term pregnancy on the 290th day of gestation. Study population was divided in two groups based on age (<35 and ≥35 years) and obesity (BMI <30 and ≥30). No statistically significant differences were recorded between younger and older women. Obese women reported a longer time between the last dose of misoprostol and cervical dilation of 6 cm (p = 0.01), a longer time between the last dose of misoprostol and delivery (p = 0.04), and a higher rate of grade II vaginal lacerations (p = 0.02). Conclusions: Maternal BMI is a factor negatively influencing the efficacy of oral misoprostol for induction of labor in late-term pregnancy.