toddler breast growing?!?!

Fo

I believe this would be related due to hormones but unsure. My daughters right breast seems to be growing, shes 19 months. It's fatty especially compared to the left side. The term I'm seeing is premature thelarche. I'm 31 weeks pregnant with a boy if that matters. Really just looking for insight if anybody has heard of this? It's kind of freaking me out. Any girl moms experienced this before?