Pregnancy and breastfeeding are associated with less later-life cognitive decline in a longitudinal, prospective cohort

INTRODUCTION: The brains of female mammals evolved to undergo structural and functional changes during pregnancy and lactation, equipping them for motherhood. However, long-term cognitive health implications of these adaptations in women are poorly understood. METHODS: In the Women's Health Initiative (WHI) Memory Study (WHIMS; n = 7427) and WHI Study of Cognitive Aging (WHISCA; n = 2304), postmenopausal women completed reproductive history interviews, annual global cognitive assessment from mean age 70 for up to 13 years, and multi-domain cognitive testing for up to 8 years. RESULTS: Each additional month pregnant was associated with higher scores of global cognition. Each additional month of breastfeeding corresponded to higher scores of global cognition, verbal memory, and visual memory. We observed equivalent results for binary formulations of gravidity and breastfeeding. DISCUSSION: Low rates of fertility and breastfeeding may have implications for postmenopausal cognitive health at the population level. Next steps include examining mechanisms linking women's reproductive history with postmenopausal cognitive health. Highlights: Motherhood may leave an enduring mark on women's brains, shaping cognitive health. Over 7000 women were assessed annually from approximately age 70 for up to 13 years. Ever being pregnant and cumulative time pregnant were linked with better cognition. Ever having breastfed and more time breastfeeding were linked with better cognition. These results imply that declining fertility may affect cognitive aging in future generations.