Globally, Pre-term birth is the leading cause of neonatal morbidity & mortality & long term Disability as well.Although secondary and tertiary interventions like steroids & surfactant use has led to reduced morbidity but the cause of preterm birth and primary prevention has remained elusive.This book gives a better understanding about properties of progesterone,its various forms and its effect in prolongation of pregnancy in patients with high risk of pre-term births.This book goes into depth after reviewing various studies about the benefit potentials of micronised progesterone in the prevention of preterm birth. It also includes the studies undertaken in All India Institute of Medical Sciences at New Delhi in which it was concluded that vaginal progesterone reduces the incidence of preterm labor and birth & need of tocolysis and neonatal outcome.