All mothers and grandmothers were informed of the study objectives and were included only after signing a written informed consent form, both at baseline and at the latest evaluation. Whenever the adolescent mother was younger than 18 years, both she and a parent/guardian signed the consent form. The anonymity of participants and the use of results for research purposes only was guaranteed. The study was approved by the Research Ethics Committee of Hospital de Clínicas de Porto Alegre, and was registered at ClinicalTrials.gov under protocol no. NCT00910377.