The 1993 Birth Cohort was created in order to propitiate a comparative analysis with the 1982 Birth Cohort data, having a 10-year interval of time between them. Thinking about the great politic and social transformations that have happened in Brazil between the 80s and 90s, the researchers wanted to analyze the evolution of health indicators and social differences.
Initially, the second cohort was planned to begin exactly 10 years after the first one. However, due to a delay in receiving the funding, the study began in 1993, which did not cause any damage related to the data validity. The design of the 1993 Birth Cohort was much more complex than the previous one. Through the 1982 Birth Cohort follow-ups, it was possible to identify that the most important changes in children’s health occur during their first year of life, which guided the concentration of the1993 studies in this period of life. Thus, besides the perinatal study, the 1993 Birth Cohort developed three more follow-up analyses and a specific study in their first year of life.
The perinatal study was similar to the 1982 one. The five maternity hospitals of Pelotas were visited between January the first and December the thirty-first of 1993. 5.265 eligible babies (alive newborns) were identified, but due to 16 refusals (0,3% of all eligible neonates), there were 5.249 participants in total. The mothers were interviewed through a standard questionnaire, which consisted of questions about socioeconomic, demographic, reproductive, behavioral, assistance and health themes. The newborns were analyzed as to identify their birth weight, their height measure and their head circumference.
For the one-month and the three-month follow-up analyses, it was selected a random sample of 13% of the babies. The interviewers visited these families in their houses, where they applied questionnaires and realized anthropometrical exams. In the six-month and 12-month follow-ups, all low birth weight babies (less than 5,5 pounds) were visited, besides more 20% of the other ones, which were again randomly selected.
Between the years of 1993 and 1994, there were also a project about mortality, which included late fetal deaths, neonates and post neonates. All the hospitals, register offices, cemeteries, and the Health Regional Department were regularly visited for detecting participant babies deaths.
Many follow-up studies and specific analyses have been made until nowadays. Generally, the follow-up studies aim at finding socioeconomic, environmental, and demographic features, as well as aspects related to diet, hospital morbidity, and health services use. This model guides the studies conducted by the 1982 Birth Cohort researchers and, so, it allows its comparison with the 1993 studies. However, the 1993 Birth Cohort studies are wider, since there are analyses of lung diseases data, ethnographic studies, analyses of oral and mental health, body composition, and habits such as smoking, alcohol use, and practice of physical and leisure activities.
The details about the 1993 Birth Cohort studies are presented in innumerous scientific articles, which have been written by the researchers of the Center of Epidemiological Research (CPE), and by the students of the Postgraduate Program in Epidemiology at UFPel. You can read some of those papers that are available at open access journals.
The instruments and the questionnaire used in the main follow-up studies and analyses are available for the scientific community.
