Key points are not available for this paper at this time.
Trends in US age at menarche vary by SEP and race/ethnicity in ways that pose challenges to several leading clinical, public health, and social explanations for early age at menarche and that underscore why analyses must jointly include data on race/ethnicity and socioeconomic position. Future research is needed to explain these trends.
Krieger et al. (2014) studied this question.