**A paradigm-shifting achievement, built from the author’s own research, showing that pregnancy profoundly transforms our brains even more than adolescence does. Dispels “mommy brain” stereotypes and trailblazes new understanding at the core of humanity with warmth and compassion.** Eighty-five percent of women experience pregnancy at some point in their lives. It is an experience enabling the very existence of our species. Yet this first step in the process of nurturing the next generation has had little serious, rigorous study—until now. Susana Carmona’s A Mother’s Brain is a landmark in ending sexual bias in women’s health. Among her many initiatives, she is building a unique longitudinal database tracking how mothers’ brains change from preconception to several years after childbirth. Drawing on her studies of individual mothers, Carmona writes with empathy about the challenges of motherhood from the reshaping of a woman’s immune system and hormonal dynamics to the geography of her cortex and its plasticity. The book reveals that pregnancy triggers rapid changes in the brain, guided by hormones, that seem to nurture maternal well-being and the mother-baby bond. Some cells with the baby’s genetic code even cross into the mother, residing in the mother’s brain for the rest of her life.