Table 5.

Health system quality and preterm delivery in studies from 2000-2010

Author, Year, (Reference No.)	Study type	n	Risk Factor
Jandaghi et al., 2011	Cross-Sectional	10913	Prenatal care•
Sehati shafaie et al., 2010	Descriptive	960	Prenatal care#
Lotf Alizadeh et al., 2005	Case-Control	600	Prenatal care #
Khalaji Nia and Sadeghi Moghaddam, 2011	Cross-Sectional	400	Prenatal care•
Zafarghandi et al., 2004	Cross-Sectional	257	Prenatal care•

^•A significant relationship between this variable and preterm delivery was found in this investigations

^#No significant relationship between this variable and preterm delivery was found in this investigations