Best method of post coital contraception is :
**Core Concept**
Emergency contraception is a medical intervention used to prevent pregnancy after unprotected sexual intercourse. The goal is to delay or inhibit ovulation, prevent fertilization, or interfere with implantation of a fertilized ovum.
**Why the Correct Answer is Right**
The most effective method of post-coital contraception is the levonorgestrel emergency contraceptive pill (ECP). It works by delaying or inhibiting ovulation and may also prevent fertilization or implantation. The exact mechanism is not fully understood, but it is thought to involve the suppression of gonadotropin release, which in turn inhibits follicular growth and ovulation.
**Why Each Wrong Option is Incorrect**
**Option A:** The copper IUD (intrauterine device) is effective as a post-coital contraceptive, but it requires insertion within 5 days of unprotected sex and is not the most effective method for immediate use.
**Option B:** The progestin-only pill is not as effective as levonorgestrel ECP in preventing pregnancy after unprotected sex.
**Option C:** The combined oral contraceptive pill is not effective as emergency contraception and may even have a negative effect if taken within 5 days of unprotected sex due to the risk of thromboembolic events.
**Clinical Pearl / High-Yield Fact**
Remember the Yuzpe regimen (combined oral contraceptives) is not recommended for emergency contraception due to its lower efficacy and increased risk of side effects.
**Correct Answer:** C. Levonorgestrel emergency contraceptive pill.