All of the following are mechanisms of action of emergency contraception, EXCEPT:
**Core Concept**
Emergency contraception refers to the use of medications or devices to prevent pregnancy after unprotected sex or a contraceptive failure. The mechanisms of action of emergency contraception involve interference with ovulation, fertilization, and implantation of a fertilized egg.
**Why the Correct Answer is Right**
Emergency contraception primarily works by inhibiting or delaying ovulation, thereby preventing fertilization. Another mechanism involves altering the cervical mucus to prevent sperm penetration, and in some cases, emergency contraception may also interfere with implantation of a fertilized egg. The hormone progesterone plays a crucial role in these mechanisms.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe a known mechanism of action of emergency contraception.
**Option B:** This option is incorrect because while it is a possible side effect of emergency contraception, it is not a primary mechanism of action.
**Option C:** This option is incorrect because it is not a well-established mechanism of action of emergency contraception.
**Clinical Pearl / High-Yield Fact**
Emergency contraception can be effective up to 5 days after unprotected sex, but its efficacy decreases with time. It is essential to note that emergency contraception is not an abortifacient and does not affect an established pregnancy.
**Correct Answer:** A.