Is induction of fetal asystole associated with adverse health outcomes during second-trimester termination induction of labor?

OBJECTIVE: To evaluate whether induction of fetal asystole (IFA) during second-trimester termination induction of labor (2T termination IOL) is associated with duration of labor and adverse health outcomes. STUDY DESIGN: We analyzed a retrospective cohort of individuals undergoing second-trimester termination IOL (2T termination IOL) between 14 0/7 to 27 6/7 weeks of gestation of a singleton at four centers from 2009 to 2019. Individuals with prelabor rupture of membranes, preterm labor, intrauterine fetal demise, or cervical insufficiency were excluded. The primary exposure was IFA. The primary outcome was duration of labor, treated continuously and dichotomously (i.e., upper quartile of the duration of labor for the cohort vs. all other quartiles). The secondary outcomes were composite morbidity and its components (uterine rupture, need for blood transfusion, clinical chorioamnionitis, intensive care unit admission, or need for readmission). Bivariate and multivariate analyses were performed, comparing individuals who underwent IFA to individuals who had fetal cardiac activity (FCA) at the time of 2T termination IOL. A priori, the receipt of mifepristone was chosen as a confounding covariate. A Kaplan-Meier curve was generated, censoring at the time of delivery. Subgroup analyses for the primary outcome were performed based on parity. A sensitivity analysis was conducted, with the use of propensity score matching, to assess for differences in all outcomes. RESULTS: A total of 358 participants were analyzed of which 83 (20.8%) underwent IFA with potassium chloride and 275 (76.8%) had FCA. There were no significant differences in the duration of labor between the two groups (13.1 h in the IFA group vs. 12.0 h in the FCA group, p = 0.84) or the frequency of experiencing the highest quartile of labor duration (26.5% vs. 24.7%, p = 0.70).There was also no difference in the composite secondary outcome (21.7% vs. 17.4%, p = 0.42) or its components (i.e., uterine rupture (p = 0.053), need for blood transfusion (p = 0.10), clinical chorioamnionitis (p = 0.96), ICU admission (p = 0.41), or need for hospital readmission (p = 1.0)). A similar pattern was noted in the sensitivity analysis. On subgroup analysis, there was no difference in the duration of labor based on parity. CONCLUSION: IFA is not associated with increased duration of labor when compared to FCA during 2T termination IOL. It is also not associated with adverse outcomes including uterine rupture, need for blood transfusion, clinical chorioamnionitis, ICU admission, or need for hospital admission.