Final answer:
Oral contraceptives reduce the risk of pelvic inflammatory disease by thickening cervical mucus and altering the menstrual cycle. They may also lower the incidence of benign breast diseases by stabilizing hormone levels.
Step-by-step explanation:
Oral contraceptives have a significant effect on the female reproductive system, including impacts on conditions such as pelvic inflammatory disease (PID) and benign breast disease. PID is commonly caused by sexually transmitted pathogens like Neisseria gonorrhoeae and Chlamydia trachomatis. Oral contraceptives can reduce the incidence of PID by providing a constant level of estrogen and progesterone. These hormones not only prevent ovulation but also thicken cervical mucus, creating a barrier to pathogens. In addition to their contraceptive function, oral contraceptives have been linked to a reduced risk of benign breast diseases, which include various non-cancerous conditions affecting the breast tissue. By regulating hormone levels and menstrual cycles, oral contraceptives may help also lower the occurrence of functional ovarian cysts and reduce menstrual pain.