It means the hormones that rise during the couple of weeks before your period and working right! All of us get some breast swelling, and some of us get some tenderness in our breasts in the days before our period comes. Your breasts are getting ready to be pregnant and later breastfeed a baby and as such need a larger blood supply. This causes veins that are already there to get swollen and appear more visibly at the surface. The color will be green, blue, or purplish depending on your underlying skin tone but this is normal. Once you have your period and your hormones go back to lower levels, your breasts are less full and the veins don’t have to process as much blood flow. They’ll get smaller and less visible again.
We all have veins that run near the surface there. I don’t know for sure why they would appear more prominent during your period, but it could be hormone-related. Check our medical expert’s answer to be sure.
I have to admit that I was excited to see this question. I was one of those odd children that instead of asking, “Why is the sky blue?” I asked things like, “Why are my veins blue?” Let me start by saying veins (and blood) are never blue or green, they are unquestionably red. The blue or green appearance is actually caused by the light’s ability to penetrate your skin and then be reflected back to your eye. The fact that these veins become more visible during your period is most likely due to the fact that your breasts are swelling. I actually experience something similar every month (my breast can increase a full cup size -- yikes!). The way I deal with it is to strap on a pushup bra and work it. Oh, and one more thing: If the veins’ greenish appearance is bothering you, there are a lot of great body makeup options out there. Hope this helps!