Final answer:
Combination oral contraceptives relieve primary dysmenorrhea primarily by creating endometrial atrophy. They reduce the production of prostaglandins by thinning the endometrial layer, which in turn decreases menstrual flow and the severity of menstrual cramps.
Step-by-step explanation:
To answer the question of how oral contraceptives relieve primary dysmenorrhea in a 15-year-old with severe menstrual pain, the correct option among the choices given is: A.
Creating endometrial atrophy. Combination oral contraceptives work by reducing the growth of the endometrial lining through the inhibition of ovulation. By preventing ovulation, there is a reduction in the production of estrogen and progesterone, leading to a thinner endometrial layer. This thinning of the endometrium results in less prostaglandin production, which is known to contribute to menstrual pain. Prostaglandins can cause inflammation and contraction of uterine muscles, leading to the cramping associated with dysmenorrhea. Therefore, by inducing endometrial atrophy, combination oral contraceptives effectively reduce menstrual flow and the severity of cramping.
It is important to note that while oral contraceptives do thicken cervical mucus and inhibit ovulation, these effects do not directly relieve menstrual pain, making Option E and hormone-related choices such as increasing prolactin or reducing inhibin levels incorrect with regards to the relief of primary dysmenorrhea.