Taking Prozac, Paxil, or other antidepressants from the class of drugs called selective serotonin reuptake inhibitors (SSRIs) can cause delays in lactation in new mothers and difficulty in breast-feeding newborns, a new study says. Researchers from the University of Cincinnati found SSRIs can result in delayed secretory activation after giving birth. SSRIs regulate the hormone serotonin in the body to stave off depression, but the hormone also is crucial to the breasts’ ability to deliver milk when it is needed, the study’s authors said.