Many things can cause women to lose hair, such as hormonal imbalances, too much stress, not eating well, and genetics. Hormones can change during pregnancy, menopause, or if someone has PCOS, which can affect hair growth. Stress can also mess with hormones and make hair fall out. Not getting enough iron, vitamin D, or protein can also make hair less healthy. And genetics, like female pattern baldness, can make hair fall out as well.