- Breasts go through changes depending on the phase of the menstrual cycle. Breasts can change in shape, size, and feel different based on what hormones are in play at the time. Tenderness, fullness, and bumpiness is common in the luteal or premenstrual phase. Sensitivity is more common during the ovulatory phase. They may grow as much as a full cup size, and shrink the same, during one menstrual cycle.
- Breast growth begins with breast buds, which are small lumps you may feel under the skin beneath your nipples. This development is likely to begin one to three years before you get your first period. Breasts may not grow at the same pace at first. In fact, it’s normal for breasts to not be exactly the same size and shape. You may be one of the 65% that have one smaller breast.
- Your breast size or shape isn’t inherited directly from your biological mom. There’s a 50/50 chance your breasts will be similar to your biological dad’s family tree. This is why, if you have sisters, you may not share the same size or shape breasts.
- Nipples also come in all shapes and sizes. Some nipples stick out from the areola (this is the name for the surrounding darker skin), while others are flat and closer to the skin. Some are known as “puffy” as the areola is also raised, and some are inverted, in which case you do not see a full nipple. Plus, nipples won’t always match!
- Breasts are complicated! Far from just fat tissue, breasts are made up of tissue, plus glands, ducts, and lobules - all set up to be ready to create breast milk that can feed a new baby. Hormones help the breasts create the exact kind of breast milk a baby needs based on their sex, age, and health.
Source
Javed A, Lteif A. Development of the human breast. Semin Plast Surg. 2013 Feb;27(1):5-12. doi: 10.1055/s-0033-1343989. PMID: 24872732; PMCID: PMC3706056. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3706056/
