“1 in 10 pregnant women” or “51 babies”? Only NPR meets challenge of interpreting new Zika numbers in context  

Kevin Lomangino is the managing editor of HealthNewsReview.org. He tweets as @KLomangino.

With a topic as serious and potentially panic-inducing as the Zika virus, reporters have a heightened obligation to present new research findings accurately and in context.

Of the dozens of stories I scanned about a new report on Zika-associated birth defects, only NPR rose to this challenge.

In lockstep with a Centers for Disease Control and Prevention news release, almost all of the other stories I looked at emphasized that “1 in 10 pregnant women” with Zika gave birth to babies with birth defects.

But how many actual women does the “1 in 10” figure represent? How many actual babies with birth defects?

You have to wade far down into all of these stories to find the numbers, whereas NPR puts them right in its headline:

The fact that 1 in 10 women with Zika have babies with birth defects is accurate but not nearly as informative as it could be.

And when communicating to a general audience, it’s misleading to the point of scaremongering to make the “1 in 10” headline the take-home message from the study.

“Since the reader doesn’t know how many pregnant women were affected by Zika, ‘1 in 10’ could mean anything in terms of absolute babies affected and presumably scares many people,” said Dr. Mirjam Jenny, Head Research Scientist at the Harding Center for Risk Literacy in Berlin. “People need to know that an absolute number of 51 babies were affected. Only communicating the rate is irresponsible.”

(Note: all of these stories and the CDC news release did include the absolute numbers in their coverage, though in most cases it was far down in the text. None called attention to the small number of women affected or tried to place the numbers in context.)

Comparisons can help readers make sense of the risks

The issue was initially brought to my attention by Twitter tipster Leah Rosenbaum, who’s in a dual journalism/public health master’s degree program at the University of California, Berkeley.

When I asked her to expand on this via email and comment on the difference between the Times and NPR coverage she wrote:

I liked the NPR piece a lot better; they framed the numbers in a way that emphasized that the disease isn’t slowing down, but also kept the numbers in perspective. I particularly liked that they compared the numbers from Zika infections to other common infections like CMV–how often is that in the news?

…Yesterday BBC put out an article about how smoking causes 1 in 10 total deaths worldwide–that’s a HUGE number! 51 babies in the entire US born with Zika-related birth defects (and only 24 confirmed) is tragic, but not on the same scale.

As Rosenbaum points out, the NPR piece notes that “each year about 8,000 babies are born in the U.S. with disabilities because of infection with cytomegalovirus, or CMV. And in general, birth defects from all causes affect more than 100,000 babies in the U.S. each year, the CDC reports.”

Kudos to NPR for going the extra mile here. They dug deep and decided not to present the statistic that would raise the most eyebrows, but the statistic that raised the right point: an absolute number that provides the information in context.

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Comments (3)

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Andrew Brown

April 10, 2017 at 10:22 am

I disagree with the contention that one statistic presents the ‘right point.’ If you are a policymaker, then yes the absolute number might be more important to you in your job. If you are a pregnant woman exposed to or diagnosed with Zika, then the 1 in 10 number would seem to be much more concerning.

    Kevin Lomangino

    April 10, 2017 at 11:06 am

    Thanks for the comment, Andrew. The fact that the 1 in 10 figure is “concerning” is exactly my point because it shouldn’t be concerning at all for the vast majority of women. If this news were targeted at women exposed to or diagnosed with Zika, then perhaps the 1 in 10 figure would be more appropriate to lead with. But it’s targeted at the general public and all pregnant women, the vast majority of whom have not been exposed to Zika and have nothing to fear. There are approximately 4,000,000 live births each year and 51 of them had Zika birth defects. So the news for most women is, I think, fairly reassuring and that’s not what the news release or these news stories conveyed.

    Kevin Lomangino
    Managing Editor

Alyssa Wolf

April 11, 2017 at 7:54 am

As a public health professional AND pregnant woman, I appreciate both statistics.