The major objective of the present review is to explicate epidemiological and clinical research evidence linking the role of psycho-social factors in preterm delivery and low birth weight. Data from epidemiological and clinical studies consistently demonstrates that prenatal maternal stress and negative mental health outcomes such as anxiety, depression and somatic health complaints are independent risk factors for preterm delivery and low birth weight. However, a relatively unrecognised methodological issue in studying psycho-social factors during pregnancy is that pregnancy itself presents unique psychological and social challenges. Unfortunately pregnancy specific measures have not been commonly included in studies related to preterm delivery and low birth weight. Further, the general implications of these findings, like some future research issues demanding attention and clinical intervention programs to reduce the occurrenceincidence of preterm delivery and low birth weight are discussed. The authors have strongly suggested that to reduce the incidence of preterm delivery and low birth weight there is a need to describe in greater detail the sociocultural, psychological and behavioural influences of mental health during pregnancy.