Long Induction Considered Safe, Does Not Increase Morbidity


RENO, NEV. — Allowing a labor induction in a nulliparous patient to proceed for up to 18 hours is a reasonable practice that does not increase the rate of serious neonatal or maternal morbidity and results in vaginal delivery for most patients.

That finding emerged from a study presented in a poster by Charla E. Simon, M.D., and associates at the annual meeting of the Society for Maternal-Fetal Medicine.

The investigators reported on the outcomes of 397 prospectively enrolled nulliparous patients undergoing labor induction, some of whom had a latent phase that went on for 24 hours.

During the first 18 hours, there was no great increase in the percentage of patients who went to cesarean delivery, and—although chorioamnionitis and postpartum hemorrhage became more frequent the longer an induction went on—this did not result in a greater rate of transfusion, hysterectomy, or prolonged hospitalization.

“I think the investigation shows we can be a little patient, and everything is still going to be okay,” Dr. Simon, of the department of obstetrics and gynecology at Northwestern University, Chicago, said in an interview.

After 18 hours, however, the rate of cesarean delivery increased significantly, as did the rate of infant admission to the neonatal intensive care unit.

All of the patients in Dr. Simon's investigation were at 36 weeks' gestation or later, and the outcomes were stratified by the length of the patient's latent phase of labor, which started with the initiation of oxytocin and the performance of an amniotomy and ended either with a cervical dilation of 4 cm with 80% effacement or with a 5-cm dilation with less effacement.

The cesarean rate was less than 20% for those with a latent phase of 0-6 hours. That rate increased to about 30% for those with a longer latent phase and stayed there, even for those in latent labor up to 18 hours. But after 18 hours, the rate rose to almost 70%.

The rate of postpartum hemorrhage was about 12% for those with a latent phase of 12-18 hours. It jumped to 26% for those with a latent phase longer than 18 hours.

The rate of chorioamnionitis was 10% for those with a latent phase of 6-12 hours, jumped to 28% for 12-18 hours, and fell to 16% for those latent over 18 hours.

Regarding neonatal morbidity, the percentage of infants with an Apgar score less than 7 was about 2% when the mothers had latent labor lasting 6-12 hours; it rose to 8% when mothers were latent for 12-18 hours, and to 10% when mothers were latent longer than 18 hours.

The rate of infants admitted to the neonatal intensive care unit was 6% when the mothers had a latent phase of 12-18 hours, and slightly more than 10% when latent labor was longer than 18 hours.

Overall, the study found that by 18 hours, 95% of the induced nulliparous women had entered active labor.

Source: Dr. Rochon

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