In hormone replacement therapy, what is the primary benefit of adding progestin to estrogen for women with a uterus?

The primary benefit of adding progestin to estrogen in hormone replacement therapy for women with a uterus is to protect against endometrial cancer. When estrogen is administered alone, it can cause stimulation of the endometrial lining, which might lead to hyperplasia and increase the risk of developing endometrial cancer. Progestin counteracts this effect by promoting the shedding of the endometrial lining, thereby reducing the likelihood of abnormal cell growth and potential cancer. This protective role is crucial for ensuring the safety of hormone therapy in women who still have their uterus, as it mitigates the risks associated with unopposed estrogen.

While other options, such as reducing osteoporosis risk or relieving menopausal symptoms, are benefits of hormone replacement therapy, they do not directly relate to the inclusion of progestin. Enhancing fertility is not a benefit of hormone replacement therapy; rather, the therapy is typically used to manage symptoms associated with menopause when fertility has naturally declined.