During pregnancy, organic changes can affect in the adolescent’s quality of life (QOL) perception. In this paper the differences in QOL by trimester of pregnancy in Argentine teenagers was determined by a cross-comparative study. The QOL was determined with the SF-36 questionnaire and the statistical analysis by the Statistical Package for the Social Sciences (SPSS) version 21. Fifty-six 18 ± 2 year old teenagers reported their QOL in a 0-100 scale (higher score, better perceived QOL) resulting a mean of 37.7 ± 8.4 in the physical component score (PCS) and 44.1 ± 12.2 in the mental component score (MCS). Differences were found in PCS comparing the first and third trimester groups (43.7 ± vs. 33.7 ± 6; p < 0.01), and the second and third trimester groups (39.7 ± vs. 33.7 ± 6; p < 0.01). The adolescents reported a lower QOL in the PCS (major physical limitation and bodily pain) with the progress of pregnancy.