The aim of this study was to determine the degree to which socioeconomic status is a risk factor for first birth at age 19 or younger in married women in an urban area of Turkey. The research was a population-based case-control study. The study group comprised all married and pregnant women aged 15–19 (adolescent pregnancies) attending primary care centres (144 subjects). Married women between 20 and 29 years of age, experiencing their first pregnancy (adult pregnancies), were determined as the control group (144 subjects). A questionnaire was completed for each subject during face-to-face interviews. Adolescent pregnancy was more frequent in women from families with a low socioeconomic status, as determined by occupation (class) and income; both were associated with adolescent pregnancy. Multiple logistic regression analysis identified seven factors associated with adolescent pregnancy: exposure to violence within the family prior to marriage; families partially opposed or unopposed to adolescent marriage; secondary school or lower education level; lack of social security; living in houses in which the number of persons per room was over 1; unemployed women; and having sisters with a history of adolescent pregnancy.