Higher Estradiol Levels Associated with Looking Younger

Lancet. 1999 Jul 17;354(9174):224. 

Oestrogen and age estimations of perimenopausal women. 
Wildt L, Sir-Petermann T.

Abstract: We estimated the age of perimenopausal women at a first visit and measured the concentrations of oestradiol in serum. The accuracy of estimation of age strongly correlated with oestradiol concentrations: age was overestimated when oestradiol was low and underestimated when oestradiol was high.