Menopause is a time of many changes. Changing hormone levels can impact everything from your skin to your mood. In fact, they can even affect your immune system. The decrease in estrogen and progesterone, particularly, can result in a reduction in your immune function, according to a 2013 review published in the Journal of Steroid Biochemistry and Molecular Biology. Here are the ways your immune system changes during this phase of life — and what it means for your health.