Theoretically, it is possible that diphenhydramine could affect a woman's milk supply, since the medication can suppress prolactin (a hormone important for breast milk production). However, this is probably not an issue for women who are well-established with breastfeeding.
PRO is a strategic communications firm helping high profile individuals, professional teams, national governing bodies, corporations and non-profits within the sports industry build their brands through the media.
: pro ranks noun A professional in any field, as distinct from an amateur, and mainly distinguished by superior and dependable performance: hear his song played and sung by pros (1866+)