We evaluated if the response to prostaglandin E2 (PGE2) induction, in pregnancies completing 41 gestational weeks, is correlated to amniotic fluid index (AFI) values. A follow-up was performed from the time of the induction to the time of delivery of 63 pregnancies resulting in a spontaneous delivery showing unfavorable cervical examination at 41 weeks of gestation. This was induced by means of intracervical administration of PGE2 gel (Dinoprostone 0.5 mg). If the cervix was still unfavorable after 12 h, another gel administration followed. The number of PGE2 administration and AFI were both used as variables to correlate the time remaining before the delivery and the probability of delivery (Kaplan-Meier and Cox algorithms). Gestational age, parity, neonatal weight, and APGAR 5' were used as covariates. A cut-off of AFI > 6 better discriminates two groups regarding the probability of delivery at paired hours from the beginning of the induction. A statistically significant difference was demonstrated in only those patients which did not deliver within 12 h (44 cases). Multivariate analysis (Cox regression) yielded an adjusted odds ratio associated to the probability of delivery of 0.47 (0.23-0.95, 95% CI, p value = 0.0354) for AFI < or = 6 vs. AFI > 6.
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