Why do womens breasts become sore during/before their period?

Not being a doctor or a woman, I can only guess.
And my guess would simply be hormones going apeshit.

Lefteh is right, hormones going apeshit…

Edit: @Dave: Duck

So they’ll have an excuse to say, “don’t fucking touch me!”

Haha all of the above, mostly the “don’t fucking touch me!” part though for me.

My girlfriend and I have kept track of the times when hers have hurt, and we’ve noticed that after every time, they got bigger and firmer.

@shilolo: <CLANG> frying pan to the head

<thud>

According to bodyandfitness: “Right before and during menstruation, higher-than-usual levels of the female hormone estrogen may cause one or both breasts to swell and become tender. Discomfort ranges from mild tenderness in some women to excruciating pain in others. (Taking oral contraceptives produces similar effects.)”

So I guess the swelling, the preparing for actual use.

@EnzoX24 Right, growing pains.~