 There's no hard data that points to why some tumors cause symptoms while others are practically invisible, but current research supports the idea that hormones play a big role. William says that long-term estrogen exposure has been linked to symptomatic fibroids. So factors like going through puberty early might increase a woman's risk. So if a girl starts having her period at eight, she's more exposed to estrogen over a longer period of time, which could result in fibroid growth.