Progesterone of choice in emergency contraception is?
First, the core concept here is emergency contraception. The question is asking which progesterone is preferred. I remember that emergency contraception can be either progestin-only or combined with estrogen. But in recent years, progestin-only methods like levonorgestrel are more commonly recommended because they have fewer side effects and are effective.
Wait, the options aren't given, but the correct answer is supposed to be levonorgestrel. Let me confirm. Levonorgestrel is a synthetic progestin used in emergency contraception. It works primarily by preventing or delaying ovulation. It's the most commonly used because it's effective when taken within 72 hours, though some studies suggest it's effective up to 120 hours. Another option might be ulipristal acetate, which is a selective progesterone receptor modulator. But the question specifies progesterone, so maybe the answer is levonorgestrel.
Now, the incorrect options: They might include estrogen-based pills (like ethinyl estradiol), which are not used for emergency contraception. Or maybe other progestins like norethindrone, but levonorgestrel is the standard. Also, options could include copper IUD, which is a non-hormonal method but very effective. But since the question is about progesterone, copper IUD isn't the answer here.
For the clinical pearl, I should mention that levonorgestrel is the first-line due to its efficacy and side effect profile. Also, note that it's most effective when taken as soon as possible after unprotected intercourse.
Wait, the user's correct answer is missing, but the example provided in the query might have had a specific answer. Since the correct answer is to be filled in, I'll structure the explanation around levonorgestrel as the correct choice. Let me check if there are other progestins used. Ulipristal acetate is another, but it's a SERM (selective estrogen receptor modulator?), no, it's a progesterone antagonist. So maybe that's a distractor. But the question is about progesterone, so the answer is levonorgestrel.
So the correct answer is likely Levonorgestrel. Let me structure each section accordingly.
**Core Concept**
Emergency contraception primarily relies on progestin to prevent ovulation, fertilization, or implantation. Levonorgestrel, a synthetic progestin, is the most widely used due to its efficacy, safety, and availability as a single-dose regimen.
**Why the Correct Answer is Right**
Levonorgestrel is the preferred progestin for emergency contraception because it effectively inhibits or delays ovulation by suppressing the preovulatory LH surge. It also alters endometrial receptivity, reducing the likelihood of implantation. Administered as a single 1.5 mg dose within 72 hours (or 120 hours for ulipristal acetate) of unprotected intercourse, it has a high success rate with minimal side effects compared to other hormonal options.
**Why Each Wrong Option is Incorrect**
**Option A:** Ethinyl