Menarche, the first menstrual period, is a recognizable marker of puberty. The timing of
menarche has important public health ramifications because an early age at menarche is
associated with breast and endometrial cancers, obesity, type II diabetes, cardiovascular disease,
and all-cause mortality (1-4). Secular trends and between-country variability in age at menarche
suggest that the onset of puberty is responsive to changing environmental conditions.
Nevertheless, the specific environmental factors that influence age at menarche remain largely
unidentified. In this dissertation we first examine sociodemographic influences on recent trends
in age at menarche using nationally-representative data from Colombia. Next, because
exposures occurring during the prenatal period are thought to play a role in the timing of sexual
maturation (5), we evaluate prenatal factors related to season and altitude that are not well
understood in relation to menarche. We finally consider the role of childhood diet. In particular,
higher animal food and/or animal protein intake might be related to an earlier age at menarche
(6). Nevertheless, individual food items such as red meat have not been sufficiently examined. In
summation, the overarching aim of this work is to gain a more complete understanding of the
sociodemographic correlates related to recent trends in menarche in a population undergoing the
nutrition transition, and to identify environmental predictors of menarche that may be amenable
to public health intervention.