Variations in Volume: Breast Size in Trans Women in Relation to Timing of Testosterone Suppression

Breast development is an important outcome for trans women receiving gender-affirming hormone therapy (GAHT). Limited breast development has been reported, possibly because of testosterone exposure during puberty. The impact of puberty suppression (PS) on breast development is unclear.

To investigate the impact of PS and timing of PS prior to GAHT on breast volume and satisfaction.

In a cross-sectional study at a tertiary gender identity clinic, 60 trans women (aged 17-57 years) after 4.5 ± 1.7 years of GAHT were included, of whom 23 initiated PS early in puberty (Tanner stage G2-3), 17 late in puberty (Tanner stage G4-5), and 20 started GAHT in adulthood without prior PS. Breast volume was measured with a 3D scanner and breast satisfaction measured with a questionnaire. Comparisons of breast volumes were adjusted for fat percentage.

Median breast volume was 115 mL (IQR, 68; 203), ie, bra cup size < A. Breast volume was 47 mL (95% CI, -9; 104) larger in the late PS group compared to early PS but this difference was only 4 mL (95% CI, -67; 75) after correction for fat percentage. Breast volume in the adult group was comparable to the early and late PS groups (adult vs early PS 27 mL [95% CI, -28; 83] and adult vs late PS -20 mL [95% CI, -80; 40]). In total, 68% of subjects were satisfied with breast size (57% of early PS, 76% of late PS, and 70% of adult group).

Early start of PS was not associated with larger breast volume, suggesting that pubertal testosterone exposure does not affect breast volume after subsequent GAHT. Despite limited breast size, most trans women were satisfied with their breast development.