Beyond the 21-cm Notch-to-nipple Myth: Golden Proportions in Breast Aesthetics

The 21-cm notch-to-nipple distance has been accepted without academic scrutiny as a key measure in breast aesthetics. The Fibonacci sequence and phi ratio occur frequently in nature. They have previously been used to assess aesthetics of the face, but not the breast. This study aims to assess if the static 21-cm measure or the proportional phi ratio is associated with ideal breast aesthetics.

Subclavicular-breast height and breast width were used to calculate the aesthetic ratio. Subjects were subsequently aesthetically rated. A one-sample t-test was used to determine if the ratio for each breast differed from phi. Breast scores with one, both, or no breasts were compared with an optimal phi ratio. Analysis of variance was performed. Tukey-Kramer adjustment for multiple comparisons was used when pairwise comparisons were conducted.

Five subjects (14%) had bilateral optimal phi ratio breasts. Four subjects (11%) had one breast with an optimal phi ratio. Subjects with bilateral optimal phi ratios had significantly higher overall breast scores than those with only one optimal breast (Δ = 0.86, P = 0.025) or no optimal breast (Δ = 0.73, P = 0.008). Distance from optimal Fibonacci nipple position was moderately to strongly correlated with aesthetic score (-0.630, P = 0.016). No correlation was found between 21-cm notch-to-nipple distance and aesthetic score.

The bilateral optimal phi ratio is correlated with high overall aesthetic scores, as is the optimal Fibonacci nipple position. No correlation was found between 21-cm notch-to-nipple distance and overall aesthetic score.