How Long After the Morning After?


Okay, okay- we already know the morning after pill is controversial- not to mention  kind of confusing. So, where else to start but with the facts?:

·         Emergency contraceptives (let's call them ECs for short) are a form of birth control used to "prevent pregnancy after sex by preventing or delaying ovulation, interfering with fertilization of an egg, or preventing implantation of a fertilized egg in the uterus by altering its lining," (WebMD).  

·         Side effects may include nausea, abdominal pain, fatigue, menstrual cramps, dizziness, vomiting.

·         The active ingredient for most ECs is levonorgestrel.

·         The sooner, the better.

o   If taken within 72 hours after unprotected sex, the pill can reduce pregnancy by up to 89% and 95% if taken within 24.


However, time may not be the only thing that plays a factor in the effectiveness of an emergency contraceptive. In Europe, HRA Pharma, a manufacturer of the emergency contraceptive Norvelo, is now putting new labels on the bottle, warning that weight may have a very major impact on the drug's effectiveness. See full story here

So the question is- does it really? And if it does, why aren't identical American ECs such as Plan B One-Step required to use similar labels?

In 2010, a study was conducted by Anna Glasier of the University of Edinburgh consisting of 3,445 women in order to identify factors associated with EC failure. The women were separated into two randomized control groups- one which took the EC 72 hours after unprotected intercourse and one which took EC 120 hours after unprotected sex. They recorded a number of things, including age, BMI, weight, ovulation times, and time from unprotected intercourse to treatment.

The results found that the most significant variable affecting the risk of pregnancy was BMI. The risk of pregnancy was 3 times higher for obese women and 1.5 times higher for overweight women. The hypothesis?: overweight women need a higher level of levonorgestrel.

This study was effective because took in to account third variables, from ovulation times to age. However, it didn't state how many obese or overweight women participated in the study. They also attempted to look at too many factors- they wanted to see which factors affected EC failure. Rather, the next study needs to focus primarily on the issue of weight in order to discover at which weight women should begin to take additional precaution.

Personally, I don't feel there is enough evidence for overweight women to not take oral contraception. It remains a good option; however, we know that weight has an effect on oral contraception, so additional precautions such as talking to a doctor should be considered. However, evidence is strong enough for HRA Pharma to begin issuing warning labels- and it's something American manufacturers should strongly consider.  


This was interesting. I always wondered if size mattered with the number of pills you take. It would make sense that a heavier person would need to take more pills than a smaller one in order for it to be effective. This article that I found states that women who are around 165 pounds the pill might not be effective for. It also says that it is not at all effective for a women who is over 176 pounds. It is expected that they change the labels for these pills so people know in advance if it will work by 2014. Check out the article below.

Sara, great post, I never knew that size went into the equation of taking (Ecs) its crazy how that can play a major role into the amount of pills you take, wow that's crazy I wonder how much pills would a woman have to take if there were over 200Ibs?

Very informative post. I wonder what they classify as "overweight" and obese. Is it based on the same scale/classifications in Scotland as in the U.S.? Results weren't completely conclusive. It leaves me wondering what else could have a strong correlation with the malfunctioning of the morning after pill.

I'm really surprised they were able to recruit that many women for this sort of experiment, to me it seems like a question of ethics.If the experiment is ethical, a potential unwanted pregnancy seems like a deterring factor from getting research participants. Something they hopefully will do in the future is create different dosage sizes for different weight categories of women, because many women weigh over the weight limit on the current pill, but are not overweight, just simply tall and muscular.


Thanks for this post. I found it to be very informative and I believe that people should read this article to learn the facts about the emergency contraceptive pill. I also didn't know that the size of the person depends on the pill that they take. I am also surprised that they were able to get women to do this study, it is not something I would think a lot of women would want to take place in because of the side effects of the pill. Another thing that is interesting is like mentioned above what qualifies as an overweight individual? How would someone know that they should take more than one pill?

I can't believe they could conduct this experiment? What are the ethics in conducting such an experiment? Wow, I'm really shocked. But anyways, what distinguishes an overweight person from an obese person?

When I examined the "overweight" versus "obese" issue further, I read some interesting information that was covered by a website called "Mother Jones." Anyways, it reports that the pill's efficacy is linked with weight, NOT body mass index, which is a measure of obesity. So, basically, weight limit could potentially affect a tall woman whose weight is actually considered healthy. So, that's something to consider.

The article I used to access the information above also included a controversial ad campaign by PETA based on the new study regarding weight and contraception. You can find it here:

Your conclusion was a great way to wrap up final thoughts, and I agree; there simply isn't enough evidence for "overweight" women not to take the contraception, but there is no harm in American manufacturers employing a potential warning label.

It makes complete sense that overweight people need to take more pills in order to gain the same effect as those who are not. When you take Tylenol they give you the amount for children and adults since their body weight plays a factor in the dissolving on the medication.

I think I read about this on Total Frat Move and thought it was just the writer being rude about women and their sizes, but now that you've provided some evidence, I don't think he was just joking around.

I think it makes sense for people to take different amounts of something in order for it to be effective, but that's not the case for other medicines. Like when I go to the doctor, he doesn't prescribe me less pills to take than say my brother because he is bigger. I think that there is always that percentage of chance in any medicine you decide to take that may not work.Contraceptives are something I don't think people should risk that chance on, but I think that it's great to even have a pill that could get you out of a sticky situation.

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