Investigating the Factors Influencing the Duration of Beginning Delivery to Hospital Discharge using Cox Regression Model

Document Type : Original Article


1 Ph.D. Student of Biostatistics, School of Health, Hamadan University of Medical Sciences, Hamadan, Iran.

2 Associate Professor, Department of Midwifery, Research Center for Child and Maternity Care, School of Nursing and Midwifery, Hamadan University of Medical Sciences, Hamadan, Iran.

3 Professor, Department of Biostatistics and Epidemiology, Research Center of Health Sciences, School of Health, Hamadan University of Medical Sciences, Hamadan, Iran.

4 B.Sc. Student of Midwifery, School of Nursing and Midwifery, Hamadan University of Medical Sciences, Hamadan, Iran.


Introduction: Pregnancy and childbirth is a great experience in a woman's life. There are several factors that increase the rate of cesarean section such as patient unawareness, financial incentives and doctors' preferences. The aim of this study was to investigate the factors influencing the duration of beginning delivery to hospital discharge using Cox regression model in Fatemiyeh Hospital of Hamadan, Iran.
Methods: This study was a prospective historical cohort. Data on 11246 pregnancies were extracted by a researcher made checklist from the files in the records department of Fatemiyeh hospital of Hamadan, Iran during 2010-2012. The response variable was hospitalization duration due to childbirth. Data were analyzed using SAS (version 9.2) and SPSS (version 19) softwares, Kaplan-Meier method, log-rank test, Cox proportional hazards, Cox-Snell residual and Schoenefeld residual. P value less than 0.05 was considered significant.
Results: The mean age of women in normal vaginal and cesarean delivery groups were 25.68±6.27 and 27.17±6.23 years, respectively. The mean of birth weight in normal and cesarean delivery groups were 2984.71±601.92 and 3030.60±554.94 grams, respectively, Median of hospitalization duration in normal and cesarean delivery groups were 29.84±18.06 and 41.46±24.59 hours, respectively. Based on the log-rank test and Cox regression model, the differences of hospitalization duration were significant in the variables including maternal age, gestational age, birth weight, number of previous pregnancies and delivery method (p<0.05).
Conclusion: With increasing birth weight, duration of postpartum hospitalization increases. Also with increasing the number of previous pregnancies, duration of post partum hospitalization decreased. Finally duration of postpartum hospitalization in cesarean delivery method is more than normal vaginal delivery method.


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