Brizendine identifies the purpose of her text as “to help women through the various shifts in their lives” (208), making hormonal changes a central theme. This focus first arises in the discussion of infantile puberty. Although Brizendine identifies some behavioral effects of female infantile puberty—like gender-stereotypical play, empathy, cooperative communication, and social aggression—the discussion of shifting hormones is intended to explain how the female brain initially diverges from the male brain, first genetically and through prenatal testosterone and then through infantile puberty. Brizendine argues that these early hormonal shifts create the biological foundation for the female brain: “Estrogen is priming these innate female brain circuits so that this little girl can master her skills in social nuance and promote her fertility” (42). The next emphasized hormonal shift occurs at puberty, which leads to sexual maturity and to the fluctuating hormones that drive the menstrual cycle. To illustrate the effects of shifting hormones, Brizendine uses Shana, a female teenager with PMDD. The examination of an individual with PMDD benefits the text by magnifying the effects of shifting hormones. Brizendine generalizes Shana’s experience to explain how female perspective can change throughout the month and to disseminate information about a relatively common disorder, PMDD, that may be overlooked due to cultural biases.