Question

Levonorgestrel is the active ingredient many emergency contraceptives (EC's) known colloquially as "Plan B" or "the morning after pill," which can reduce the risk of pregnancy if administered following unprotected intercourse. Use that information to answer the following questions.

1. Clinical trials have determined that the likely mechanism of EC is disruption or elimination of the LH surge. Why would this be effective in preventing fertilization?

2. The manufacturers of plan B report that when taking it within 24 hours of unprotected sex, it is 95% effective. If taken between 48 and 72 hours of unprotected sex, the efficacy rate is 61%. Given its mechanism and your understanding of fertilization and conception, why would the efficacy rate drop substantially in just a couple days?

Answer 1

Answer 1

Levonorgestrel is a progestins.

• It prevents the release of an egg from the ovary and also prevent the fertilization of the egg by sperm .
• It alters the lining of the uterus prevent development of a pregnancy.

Answer 2

The timings when the patient administers this pill is important.

• Within 24 hours it inhibits ovaluation. Thus it's succes rate of inhibiting pregnancy is more.
• Later it prevents implantation in 48 -72 hours (the chances of getting egg implanted are 50:50).