Adolescence is chronologically defi ned by the World
Health Organization (WHO) as the period from ten to
19 years old. It is characterized by profound and extensive
changes in physical and psychological aspects,
with individual, family, and social repercussions.16
Brazil is in a phase of demographic transition, characterized
by a signifi cant reduction in the fecundity
rate associated with a corresponding dislocation of
reproduction to older age ranges, especially in areas of
greater development, similar to what has occurred in
central, industrialized countries.3 In Pelotas, Southern
Brazil, there was an increase in the proportion of
mothers at the extremes of reproductive life (< 20 years
or ≥ 34 years) over a period of two decades (1982, 1993
and 2004). The percentage of adolescent mothers in
2004 was higher than in the two previous cohorts.19
Low birth weight (LBW, birth weight < 2,500 g) is
particularly important among the problems associated
with increased perinatal mortality and morbidity
when the outcome of pregnancy is evaluated. It is also
the most important independent indicator of infant