No, not if you're careful with your teeth. It is actually a pleasure for a girl to have someone suck on her breasts.
No, a girl can suck breasts as a young girl or woman and no harm will come of it.
Studies show that those who have had babies are less likely to get breast cancer.
Sucking breast of female can not hurt if done gently. Touching or sucking breast hard can damage them which can lead to very serious health concern. Secondly, sucking of breast increases a hormone level called prolactin. High levels of this hormone can cause cycle irregularities, milk production at wrong time and infertility. But this can happen in only those ladies which have upper normal levels of prolactin.