Factors associated with the length of the latent phase during labor induction.
OBJECTIVE
To evaluate the factors that are associated with the length of the latent phase during labor induction in nulliparous women.


METHODS
During a 6-month period, all nulliparous women with a viable fetus of at least 36 weeks gestation who underwent induction of labor were identified. Demographic and intrapartum data were abstracted from the medical record. In an effort to understand the association of different factors with the length of the latent phase, both univariable and multivariable analyses were employed.


RESULTS
The median length of the latent phase for the women available for analysis (N=397) was 384 min with an interquartile range of 240-604 min. In univariable analysis, a greater maternal age, a medical indication for induction, and unripe cervical status at admission (assessed by either modified Bishop score or use of cervical ripening agents) were significantly associated with a latent phase of at least 12 h. In multivariable analysis, the only variables that continued to be independently associated with a latent phase of at least 12 h were modified Bishop scores of 0-2 (adjusted odds ratio 42.0, 95% confidence interval 9.7, 183.2) and 3-5 (adjusted odds ratio 9.3, 95% confidence interval 2.1, 40.9).


CONCLUSIONS
A woman's modified Bishop score at admission for labor induction, but not other risk factors typically associated with cesarean, is associated with length of the latent phase.
Grobman
William A
WA
Department of Obstetrics and Gynecology, Northwestern University Medical School, 333 East Superior Street, Suite 410, Chicago, IL 60611, United States. w-grobman@northwestern.edu
Simon
Charla
C
D000328:Adult; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007747:Labor Stage, First / Q000502:physiology*; D007751:Labor, Induced / Q000009:adverse effects*; D010298:Parity / Q000502:physiology*; D011247:Pregnancy; D012189:Retrospective Studies; D013997:Time Factors