Which one of the following is an adverse effect associated with combined oral contraceptives:
**Core Concept**
Combined oral contraceptives (COCs) are a type of hormonal birth control that contains both estrogen and progestin. They work by inhibiting ovulation and altering the cervical mucus and endometrial lining to prevent fertilization and implantation. However, COCs can cause various adverse effects due to their hormonal activity.
**Why the Correct Answer is Right**
The correct answer is associated with the mechanism of action of COCs. Progestin in COCs can cause an increase in clotting factors, such as factor VII, factor VIII, and fibrinogen, which can lead to an increased risk of venous thromboembolism (VTE). This is because progestin can stimulate the production of these clotting factors, making the blood more prone to clotting. Furthermore, the estrogen component can also contribute to an increased risk of VTE by increasing the levels of clotting factors and decreasing the levels of anticoagulant proteins.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not a well-known adverse effect of COCs. While COCs can cause changes in blood pressure, they are not typically associated with an increased risk of hypertension.
**Option B:** This option is incorrect because it is not a direct adverse effect of COCs. While COCs can cause changes in mood and libido, they are not typically associated with an increased risk of depression.
**Option C:** This option is incorrect because it is not a well-known adverse effect of COCs. While COCs can cause changes in liver function, they are not typically associated with an increased risk of liver failure.
**Clinical Pearl / High-Yield Fact**
It is essential for patients taking COCs to be aware of the increased risk of VTE and to report any symptoms of deep vein thrombosis, such as swelling, pain, or redness in the legs, to their healthcare provider promptly.
**Correct Answer: C. Venous thromboembolism**