The objective of this study is to estimate the effect of m aternal age on obstetric outcomes. This is a prospective descriptive investigation of subjects referring to Bandar Abbass Shariaty M aternity Hospital. Subjects were selected and divided into 3 age groups: 1) ≤18 years, 2) 19-34 years, and 3) ≥ 35. The frequencies of preterm labor, placenta previa, low birth weight, abortion, pregnancy-induced hypertension, abruption, macrosomia and gestational diabetes were compared. 2940 women with complete data were available: Six percent were 18 or less than 18 years of age; 79.7% were19-34 years; and 14.3% were 35 years or older. Preterm labor and placenta previa were significantly higher in less-than 18 yrs group. In our study maternal age in the two extremes affected pregnancy outcome. Yet, age was not independently associated with specific adverse pregnancy outcomes.