Optimal Admission Cervical Dilation in Spontaneously Laboring Women.
OBJECTIVE
To estimate the impact of admission cervical dilation on the risk of cesarean in spontaneously laboring women at term.


METHODS
Secondary analysis of a prospective cohort study of women admitted in term labor with a singleton gestation. Women with rupture of membranes before admission, induction of labor, or prelabor cesarean were excluded. The association between cesarean and cervical dilation at admission was estimated, and results were stratified by parity. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated, using cervical dilation ≥ 6 cm as the reference group. Cesarean for arrest was secondarily explored.


RESULTS
A total of 2,033 spontaneously laboring women met inclusion criteria. Women admitted at <6 cm dilation had an increased risk of cesarean compared with those admitted at ≥6 cm (13.2 vs. 3.5%; RR 3.73; 95% CI 1.94-7.17). The increased risk was noted in nulliparous (16.8 vs. 7.1%; RR 2.35; 95% CI 0.90-6.13) and multiparous (11.0 vs. 2.5%; RR 4.36; 95% CI 1.80-10.52) women, but was statistically significant only in multiparous women.


CONCLUSIONS
Decreasing cervical dilation at admission, particularly <6 cm, is a modifiable risk factor for cesarean, especially in multiparous women. This should be considered in the decision-making process about timing of admission in term labor.
Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
Amber M
AM
Wood
Department of Obstetrics and Gynecology, The Ohio State University College of Medicine, Columbus, Ohio.
Heather A
HA
Frey
Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
Methodius G
MG
Tuuli
Department of Obstetrics and Gynecology, Oregon Health Sciences University, Portland, Oregon.
Aaron B
AB
Caughey
Department of Obstetrics and Gynecology, University of South Florida, Tampa, Florida.
Anthony O
AO
Odibo
Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
George A
GA
Macones
Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
Alison G
AG
Cahill
D000328:Adult; D000367:Age Factors; D002585:Cesarean Section / Q000706:statistics & numerical data*; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007747:Labor Stage, First; D007743:Labor, Obstetric; D010298:Parity; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D047929:Term Birth; D013997:Time Factors; D055815:Young Adult