Plan B — Will it Work for You?

Earlier this week, news outlets were filled with warnings about the differences in the effectiveness of emergency contraception (EC) relative to a woman’s weight or body mass index (BMI).

In case you missed it, the big news is that the European version of Plan B will start carrying a warning telling women over 165 pounds that the drug is less effective for them and women over 176 pounds that it likely won’t work for them at all.

The news raises concerns among U.S. women about the effectiveness of Plan B for women of a certain size. Here at the FPA, our clinical leadership was quick to respond. We’ve read the studies and reviewed the recommendations from experts in the field of reproductive health, in order to update our own clinical guidelines in relation to EC.

Here’s the scoop.The effectiveness of Plan B does decrease significantly in women with BMIs of 26 or higher.

Although many news reports have focused on weight as the determining factor for Plan B effectiveness, the Association of Reproductive Health Professionals (ARHP) uses BMI as its measure. (BMI takes both height and weight into account. You can calculate yours here.)

The ARHP are the people who literally wrote the book on birth control. Contraceptive Technology is a weighty volume chock full of the most up-to-date, detailed information about birth control. It’s like the holy grail of medical guides for our field of medicine.

Here’s the lowdown on EC and BMI:

Copper IUD: The most effective option for people of any weight is getting a copper IUD inserted by a health care provider. When inserted within 5 days of having unprotected sex, the effectiveness of the copper IUD is greater than 99% no matter how much a woman weighs.

Ella: If taking a pill is the preferred option, Ella is the brand of EC that works best for women with higher BMIs–up to a certain point. For women with a BMI higher than 35, it’s less effective (but still worth a shot if getting an IUD isn’t  possible). Our family planning health centers don’t carry Ella but we can write a prescription for patients who request it.

Plan B One-Step: For situations where the IUD or Ella aren’t options, it’s perfectly safe to take Plan B One-Step. This pill is available over the counter at most pharmacies and at all of Maine’s family planning health centers.

Unfortunately, it’s less effective at preventing pregnancy for many women. Plan B begins to lose effectiveness  for those of us with a BMI of 26 or higher. And for women with a BMI higher than 30, it may not work at all.

For women concerned about whether EC will work for them, we suggest getting a personalized recommendation from a health care provider. And since Maine’s family planning providers are experts on this topic, we encourage a call to one of our health centers.

~ Nancy



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