Cardiotocographic abnormalities associated with misoprostol and dinoprostone cervical ripening and labor induction

Abstract

Objective: To characterize the incidence and timing of cardiotocographic (CTG) abnormalities associated with misoprostol and dinoprostone vaginal inserts during labor induction.

Study design: This was a secondary analysis of data collected during the misoprostol vaginal insert (MVI) trial, a multi-site, double-masked, randomized trial of women requiring cervical ripening before induction of labor. The timing, incidence and clinical outcomes associated with CTG abnormalities were analyzed among three study groups.

Results: 1308 subjects were randomized to receive dinoprostone pessary, misoprostol 50 mcg (MVI 50) or 100 mcg (MVI 100) vaginal insert. 6.8% of MVI 50-treated women had a uterine contractile abnormality (hyperstimulation, hypertonus and/or tachysystole) while the study drug was in situ, compared to 17.4% with dinoprostone insert (p<0.001) and 17.3% with MVI 100 (p<0.001). There was no significant difference in incidence of fetal heart rate (FHR) abnormalities that occurred with the study drug-11.2% with dinoprostone, compared to 9.9% with MVI 50 and 10.7% with MVI 100. Cardiotocographic (CTG) abnormalities while the study drug was in situ occurred later in women treated with MVI 50 (7.5h [6.2-9.8]) compared to dinoprostone (5.5h [4.2-6.6], p=0.003) and MVI 100 (7.0 h [5.7-7.9], p=0.13). Eight participants in MVI 50 group underwent cesarean section secondary to a CTG event that was initially noted with the study drug in situ, compared to eight dinoprostone-treated participants and 16 in the MVI 100 group, but these differences were not statistically significant.

Conclusion: Cardiotocographic abnormalities were less frequent and occurred after longer exposure with MVI 50 than MVI 100 or dinoprostone. Clinical outcomes were similar among the groups.