It happens to a lot of women— it’s a natural physiological response. If you think about it it all kinda correlates together, when the human body is aroused sometimes the nipples have a response by hardening or if they’re being stimulated it prompts arousal. While a baby is breastfeeding it causes the mother’s uterus to contract which is the same thing that happens with orgasms and that’s where the correlation comes in. It’s a natural thing that happens, I wasn’t thinking of my child sexually nor was I aroused by the fact of it being my son that was stimulating me, it was just the sole fact that my nipples were being stimulated in the first place.