Normative data for uterine size according to age and gravidity and possible role of the classical golden ratio

Abstract

To document normal measurements (length, width, anteroposterior (AP) diameter) and proportions of the non-pregnant uterus according to age and gravidity. We hypothesized that uterine proportions conform to the classical 'golden ratio' (1.618). This was a retrospective study of ultrasonographic measurements of the length, width and AP diameter of non-pregnant uteri recorded in our database between 1 January 2000 and 31 July 2012. All patients for whom abnormal findings were reported were excluded and only the first set of measurements for each patient was retained for analysis. Loess (local regression) analysis was performed using age and gravidity as explanatory variables. Measurements of 5466 non-pregnant uteri were retrieved for analysis. The mean length was found to increase to 72 mm at the age of 40 and decrease to 42 mm at the age of 80 years. Gravidity was associated with greater uterine length, width and AP diameter. Mean length/width ratio was found to be 1.857 at birth, decreasing to 1.452 at the age of 91 years. At the age of 21 years, the mean ratio was found to be 1.618, i.e. equal to the golden ratio. Increasing gravidity was associated with lower mean length/width ratio. Uterine size in non-pregnant women varies in relation to age and gravidity. Mean length/width ratio conformed to the golden ratio at the age of 21, coinciding with peak fertility.