Emergency contraception, also known as the morning after pill, is birth control that can be used to prevent pregnancy up to 120 hours after unprotected sex, according to Planned Parenthood.  In addition to the pill, there is another form of emergency contraception in the form of an IUD called ParaGard.  Emergency contraception is available at pharmacies and health centers around the country, ranging from $35 to $65 for the pill and $500 to $900 for the IUD.  Planned Parenthood indicates that the pill is 89 percent effective within 72 hours and 85 percent effective within 120 hours.

However, 2011 research published in the journal Contraception indicated that the risk of pregnancy was three times higher for obese women as compared to women with a normal body mass index (BMI).  This risk differential persisted even after taking emergency contraception.  According to Mother Jones, manufacturer HRA Pharma investigated the effectiveness of Norlevo, a morning after pill, in response to this research.

Now, new leaflets from HRA Pharma that accompany each box of Norlevo warning women that if they are above a certain weight, the product may not be appropriate or effective.  These warnings are only being distributed to European consumers.  The U.S. Food and Drug Administration (FDA) prohibits generic drug manufacturers from changing product information unless the brand name manufacturer makes a change, companies that manufacture generic versions of Plan B One-Step cannot update their packaging information unless Teva Pharmaceutical Industries, the exclusive manufacturer of Plan B One-Step, acts first.  Thus, American manufacturers do not currently advise American customers of weight limits for levonorgestrel-based emergency contraceptives.

Time Health & Family reports that the leaflet warns consumers that the drug is completely ineffective for women over 176 pounds, and begins to lose effectiveness after 165 pounds.  This is alarming because current weight data indicates that the average American woman is above this effectiveness threshold.  The average woman weighs 166 pounds, and the average non-Hispanic black woman between 20 and 39 weighs about 186 lbs. If the European manufacturer is correct, morning-after pills could be ineffective for many American women.

There are other products that may be able to fill the gap, but currently Plan B One-Step is the only emergency contraception available over-the-counter, or without a prescription.  For example, according to RxList, Cytotec is used for ulcers, but has a strong warning against use by pregnant women.  The warning notes it can cause abortion, premature birth, or birth defects.