Plan B and Pregnancy: An Overview
One-Step™ (levonorgestrel) is a "morning-after pill" (emergency contraceptive) that is used to prevent pregnancy after unprotected sex. As with all hormonal contraceptives, Plan B should not intentionally be used during pregnancy. However, it will not disrupt an established pregnancy.
Plan B and Pregnancy Category X
The U.S. Food and Drug Administration (FDA) uses a category system to classify the possible risks to a fetus when a specific medicine is taken during pregnancy. Pregnancy Category X is given to medications that should not be used during pregnancy. Often, this is due to problems such as miscarriages or birth defects.
Although Plan B is a pregnancy Category X medication, it is unlikely to cause any problems if it is accidentally used during early pregnancy. Many studies have shown that there is no increased risk of birth defects when birth control pills
are accidentally taken during early pregnancy. In addition, Plan B will not cause an abortion of an established (implanted) pregnancy. There is no good reason to take the drug if you already know you are pregnant. It will have no effect on the developing pregnancy.
Plan B and Pregnancy: What Are the Odds?
Plan B is not 100 percent effective. In fact, it is significantly less effective than many other types of birth control, which is why it should not be used as your main method of birth control. After any one act of unprotected intercourse, the average woman has an 8 percent chance of getting pregnant. If she takes Plan B within 72 hours of having unprotected intercourse, that risk is reduced to about 1 percent. If you happen to be in that 1 percent, rest assured that Plan B does not increase the risk of birth defects or other problems.