A Trend Study of Preterm Infant Mortality Rate in Developed and Developing Countries Over 1990 to 2017 - SEFIDKAR, Reyhaneh; ZAYERI, Farid; KAZEMI, Elaheh; SALEHI, Masoud; DEHNAD, Afsaneh; HAFIZI, Maryam (Iranian Journal of Public Health, 2021)