A new study claims breastfeeding moms are more likely to be aggressive when provoked. They're known as "mama bears." Women who nurse have lower blood pressure, limiting their fear response and allowing them to better react to threats. However, this doesn't mean mama bears are going around looking for bar fights, researchers assure. These findings add to the stigma Americans place on nursing mothers. A previous study suggests they're seen as less competent. Will breastfeeding ever gain full acceptance in the US, or will it forever be considered taboo?