1. Division of Neonatology, Department of Pediatrics, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran,
2. Center for Nursing Care Research, Iran University of Medical Sciences, Tehran, Iran,
3. School of Nursing and Midwifery, Shahroud University of Medical Sciences, Shahroud, Iran,
4. Statistic and Mathematics Department, School of Health, Iran University of Medical Sciences, Tehran, Iran, and
5. Department of Epidemiology and Biostatistics, School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran