Lydia* first started thinking about weight-loss drugs during pregnancy. Everyone was talking about them and the advertisements were everywhere, she says, as her baby son naps upstairs. I remember thinking: That's how I'll lose weight for my wedding next year.' When Lydia explains that most of her life before pregnancy was spent in a welter of yo-yo dieting and body dissatisfaction, I say to her that I think most of us can relate.
Parity and breastfeeding reduce the risk of breast cancer, particularly triple-negative breast cancer (TNBC)1,2, yet the immunological mechanisms underlying this protection remain unclear. Here, we show that parity induces an accumulation of CD8+ T cells, including cells with a tissue-resident memory (TRM)-like phenotype within human normal breast tissue. In murine models, pregnancy followed by lactation and involution drove the accumulation of CD8 T