OBJECTIVE: To identify risk factors for difficult delivery among nulliparas in the second stage of labor with continuous epidural analgesia, and to develop a multivariable model that is predictive of difficult delivery.
METHODS: The database is derived from a multicenter randomized trial of delayed pushing for nulliparous women under continuous infusion epidural. Members of this cohort (n = 1862) were randomly divided into two groups: a “Model Development” and a “Model Validation” group. We used univariate and multivariable techniques to assess associations between anthropometric, sociodemographic, and obstetric variables and difficult delivery.
RESULTS: With the referent defined as the category of lesser risk, the developed model showed that the risk of difficult delivery was increased for women with height less than 160 cm (odds ratio [OR] 2.1, 90% confidence interval [CI] 1.2, 3.4), prepregnancy weight greater than 65 kg (OR 1.6, 90% CI 1.0, 2.6), age greater than or equal to 35 years (OR 3.0, 90% CI 1.1, 8.1), and gestational age greater than or equal to 41 weeks (OR 1.8, 90% CI 1.1, 2.8). Induction of epidural analgesia late in labor (greater than or equal to 6 cm) was associated with a higher risk of difficult delivery than induction between 3 and 5 cm (OR 1.9, 90% CI 1.3, 2.8). An interval of greater than or equal to 360 minutes between epidural induction and full dilatation increased the risk of difficult delivery (OR 3.8, 90% CI 1.5, 9.5). Fetal station above +2 at full dilatation and a posterior fetal position were both strongly associated with difficult delivery (OR 2.7, 90% CI 1.4, 5.0, and OR 11.2, 90% CI 4.9, 25.6, respectively). For the multivariable predictive model, when the sensitivity was 57%, the specificity was 75%, and the positive predictive value was 35%.
CONCLUSION: Our observations concerning maternal characteristics and obstetric variables are consistent with previous observations with the exception of time of induction of the epidural. The predictive model may be useful in defining high‐risk populations for subsequent intervention studies designed to assess approaches to reduce difficult delivery.
Hôpital St‐François d'Assise (CHUQ) Research Center, Department of Obstetrics and Gynecology, and Department of Social and Preventive Medicine, Laval University, Québec, Canada.
Address reprint requests to: William D. Fraser, MD, MSc, Hôpital St‐François d'Assise (CHUQ) Research Center, 10 rue de l'Espinay, local D1–724, Québec, G1L 3L5, Canada; E‐mail: firstname.lastname@example.org.
The following is a list of the PEOPLE Study Group. Steering Committee: William D. Fraser, MD, MSc, Sylvie Marcoux, MD, PhD, Isabelle Krauss, MD, MSc, Joanne Douglas, MD, and Céline Goulet, RN, PhD. Center Investigators and Research Assistants: J. Chabot, MD, J. Flamand, RN, L. Laperriére, BN, CHUQ ‐ Pavillon St‐ François d'Assise, Québec, Qc; P. Fish, MD, G. Hamel, RN, Hôpital de Chicoutimi, Chicoutimi, Qc; R. Sabbah, MD, L. Vincelli, RN, Hôpital Sacré‐Coeur de Montréal, Montréal, Qc; G. Tawagi, MD, O. Rosag, MD, J. Belcher, RN, Ottawa Civic Hospital, Ottawa, Ont.; F. Galerneau, MD, M. Klein, MD, J. Swenerton, MD, B. Weibe, RN, E. Nickel, RN, BC Women's Hospital, Vancouver, BC; K. Milne, MD, J. Fuller, MD, L. Watson, RN, St. Joseph's Hospital, London, Ont.; O. Irion, MD, K. Rifat, MD, V. Mentha (Midwife), Hôpitaux Universitaires de Genéve, Geneva, Switzerland; S. Bottoms, MD†, B. Steffy, RN, Hutzel Hospital, Detroit, MI; M. Helewa, MD, S. Lucy, MD, S. Erickson, RN, St. Boniface Hospital, Winnipeg, Mb.; N. Okun, MD, A. Guest, MD, A. Stuart, MD, D. Schimeck, RN, University of Alberta Hospital, Edmonton, Ab.; M. Sermer, MD, M. Bailey, RN, Toronto General Hospital, Toronto, Ont.; D. Blouin, MD, Y. Claprood, and D. Beaulieu, RN, Center Hospitalier Universitaire de l'Estrie, Sherbrooke, Qc. Data Management Committee: Michel Boulvain, MD, PhD, Sylvie Bérubé, PhD, and Isabelle Faron. Safety and Efficacy Monitoring Committee: François Meyer, MD, PhD, Aida Bairam, MD, PhD, and Jean‐Marie Moutquin, MD, MSc.
This study was sponsored by the Medical Research Council of Canada (grant # MT‐12423). AstraZeneca R&D Montréal, Montréal, Québec, Canada, provided medication. The data presented are part of the Master's Thesis of Mireille Cayer.
Received June 21, 2001. Received in revised form November 9, 2001. Accepted November 19, 2001.