Factors Influencing the Use of Labor Management Interventions and Their Effect on Cesarean Birth

Abstract

Background: The cesarean birth (CB) rate of 31.9% in the US is concerning because the procedure is associated with increased maternal mortality as well as increased maternal and neonatal morbidity. Women considered low-risk for CB are defined as nulliparous and pregnant with a term, singleton gestation in the vertex position (NTSV). Even among NTSV women, cesarean rates range from 2.4% to 36.5% across hospitals, suggesting that CB may be influenced by differences in practice patterns, including admission triage, the use of labor management interventions (e.g., amniotomy, epidural analgesia, and oxytocin augmentation), and availability of a laborist. Purpose: The following were examined in three manuscripts: (1) influence of cervical dilation at admission on labor management and CB, (2) influence of provider and hospital characteristics on labor management and CB, (3) influence of combinations of labor management interventions on likelihood of CB. Methods: All three manuscripts were cross-sectional, observational studies of NTSV women with spontaneous onset of labor whose births occurred from 2002-2007 at hospitals included in the National Institutes of Health Consortium on Safe Labor. Samples sizes varied due to missing data but ranged from 17,443 to 26,259. Generalized linear mixed modeling was used to account for the effects of hospital and provider clusters. Results: Greater dilation at admission (>6 cm) was associated with a lower likelihood of receiving all three interventions (RR 0.40, CI95 0.35-0.46) and a lower likelihood of CB (4-5 cm: RR 0.44, CI95 0.40-0.49; >6 cm: RR 0.20, CI95 0.17-0.24). Midwives were more likely to use no interventions compared to obstetrician/gynecologists (RR 1.81, CI95 1.50-2.19). Women delivering at hospitals with an as-needed laborist available had a greater likelihood of receiving no interventions (RR 4.27, CI95 1.43-12.70) compared to those at hospitals with a 24/7 laborist. Compared to no interventions, use of all three interventions was associated with an increased likelihood of CB (RR 1.84, CI95 1.53-2.21). Conclusion: Admitting women at more advanced cervical dilation may reduce the use of labor management interventions and CB. The combined use of labor management interventions should be considered carefully given the association with an increased likelihood of CB.