For many women, it happens like clockwork: the inevitable swelling, tenderness and pain that afflict many of us right before our least-looked-forward-to days of the month.
Some women experience it as an uncomfortable inconvenience, while others wince at the mere thought of wearing anything more constricting than a cotton t-shirt.
Breast pain is one of the most common pre-menstrual symptoms that women suffer through. But, why?
Dr. Channa Jayasena of the Society of Endocrinology tells Broadly that this "very natural and common phenomenon" is due to the release of estrogen at the beginning of a woman's menstrual cycle. Estrogen is responsible for stimulating breast tissue growth.
Then, towards the end of the cycle, our body releases progesterone, which encourages the breast to make milk.
"Both of these hormones work on the breast in different ways," Dr. Jayasena explains, "and because they're altering in dominance every few weeks, there are cyclical changes in how the breast feels. That can cause tenderness."
Although our bodies are in constant flux, the amount of discomfort we feel in our breasts can be affected by age, body weight, and general health.
There is really no way to eliminate breast pain completely, but Dr. Jayasena advises women to "have a well-fitting and supportive bra and take painkillers."
So, when that time of the month comes around and your period panties are in rotation, add a period sports bra to the roster and break out the pain killers.
But remember - if your nipples change color, become lumpy or produce a brownish discharge, see your physician as soon as you can, these could be symptoms of breast cancer.