I've heard that the horomones released during and after sexual activity are similar tot he pregnancy ones, and this can cause the breasts to grow. Also, some birth control pills can also cause breast enlargement.

My bf swears mine have gotten bigger since I started my bc... I think it's just him imagining things lol. But if he thinks they're bigger, then ok!

Thanks for the reply, just been wondering. I think it's just hormones or something, because I wasn't on bc before, but mine just got bigger about a month or so after.

I had sex like, 9 or so months before I started my new birth control pill, and I never had any change in my breast size until I started this pill. They seem a lot bigger to me...But they're small anyways...Maybe it's wishful thinking, but my boyfriend thinks they are too, so I just agree, haha ...Hope this helped!