Breast development, particularly during feminising hormone therapy or puberty, involves several stages and physical changes. These changes can vary significantly in their progression and final outcome based on genetic, hormonal, and individual health factors.

Stages of Breast Development

Thelarche (Breast Budding):

- **Timing**: This is usually the first sign of breast development, often occurring within the first 1-6 months of hormone therapy or during early puberty.
- **Features**:
    - Small, firm, tender lumps, known as breast buds, form under the areola (the pigmented area around the nipple).
    - The areola may start to enlarge.
    - There might be some discomfort or sensitivity due to the tissue growth and hormonal changes.

Breast Growth and Fat Distribution:

- **Timing**: Progresses over the next several months to years.
- **Features**:
    - The breast tissue starts to grow beyond the areola, gradually forming the breast mound.
    - Fat distribution changes, contributing to the rounder, fuller shape of the breasts.
    - The breasts may grow at different rates, so asymmetry during this stage is common.
    - The continued enlargement of the areola and nipple.

Further Development and Maturation:

- **Timing**: This stage can vary greatly among individuals, from months to several years.
- **Features**:
    - The breasts continue to enlarge and mature in shape.
    - Breast and nipple sensitivity may decrease as the growth slows down.
    - The fullness of the breast develops, which may include the rounding of the upper part of the breast.

Final Shape and Size:

- **Timing**: Typically, the final size and shape of breasts are reached after a few years of hormone therapy or after puberty, but they can continue to change subtly over time.
- **Features**:
    - The breasts reach their final adult size and shape, though this can be influenced by weight changes, hormonal fluctuations, and aging.
    - Breast tissue composition stabilises, usually being softer and less firm than during the initial stages of growth.
    - The areola and nipple may become more proportionate to the increased breast size.

Other Considerations

• Variability: Individual experiences with breast development can vary widely. Factors like age at the start of hormone therapy, genetics, and overall health play significant roles in the development process and final outcomes.
• Nipple Development: Nipple and areola growth can also occur, although the extent of this varies from person to person.
• Sensitivity and Discomfort: Tenderness and sensitivity are common throughout the breast development process. This is typically most pronounced during the early stages but usually subsides as the breasts mature.
• Asymmetry: It’s normal for breasts to develop asymmetrically, with one breast growing faster than the other initially. Over time, they usually become more symmetrical, but complete symmetry is rare, even in cisgender women.

Breast development is a significant aspect of feminisation for many transgender women and non-binary individuals. It’s important to have realistic expectations and to discuss any concerns with a healthcare provider, especially regarding the potential final size and shape of the breasts.