Reasons for Hair loss in Females: Women can lose hair due to various reasons, some being simple and reversible and some pretty serious. To mention some, physical and emotional stress, pregnancy, too much vitamin A, vitamin B12 deficiency, lack of protein, anemia, lupus, hypothyroidism, too much weight loss, PCOS, medicines like antidepressants, blood thinners, overstyling, trichotillomania.