Calling bullshit on mobile phone use during pregnancy damaging babies

The headline reads - "Warning: Using a mobile phone while pregnant can seriously damage your baby" - when it should read - "Danish mother's self-reported use of cell phones during pregnancy (seven years ago) is associated with a possible increase of mother's self reported behavioral problems of 7 year olds as measured by the Strengths & Difficulties Questionnaire from 10% of total children to 14%-22% of total children." I guess that headline is a little too long and exacting to sell papers or get the links. I am not the only one that thinks this, there are others.

In reading this news report and looking into the study I have discovered some obvious facts:

• Newspaper headlines are written sensationally to increase sales and readers.
• Cell phones, pregnant women and babies are easy targets.
• I am way too cheap to pay $35 for one academic article in Epidemiology.
• In spite of that you can still find some analysis for free on the internet.

So first I will admit that I did not read the actual article in Epidemiology by Divan HA, KheifetsLeeka, Obel C, and Olsen J because I was too cheap to buy it. But I did find a good summary of the points at EMF-portal and I was able to read the abstract. Some observations about the study:

• The cell phone use during pregnancy was self-reported and it seems that it was self-reported seven years after the fact.
• 50% of the children in the study were never exposed to cell phone use. Only 11% were exposed during pregnancy and used a phone before they were 7.
• Behavioral problems in 7-year old children were assessed using the Strengths and Difficulties Questionnaire. That is also self-reporting, mothers filling it out about the children.
• 90% of the children in the study had no behavioral problems.
• The paper reports an odds ratio (ratio of the odds of disease in an exposed group over the odds of disease in an unexposed group) of 1.8 with 95% confidence interval from 1.45-2.23, which combined with the 10% abnormal data above suggests the increase from 10% with behavioral problems to ~14%-22% of children with behavioral problems as defined by the SDQ.

The SDQ data from the testing website itself supports the ~90% normal figure in the Kheifets paper. This is the same figure for 4 to 7 year olds in the US. (click below for larger, .pdf link to data, .pdf link to normal vs. abnormal scores)

The authors of the paper certainly do not present a conclusion like the sensational headline above. Prenatal and postnatal exposure to cell phones was associated with overall behavioral problems in children. The authors themselves concluded that these results should be interpreted with caution. The observed association is not necessarily causal and may be due to factors not investigated in this study.

I wish that reporters and the general public read the news and these studies with the healthy skepticism and critical thinking that is required to understand them and to modify their behaviors only in the face of actual understood risk. That also does not sell newspapers.

If someone sends me the article or the $35 for it I will happy to complete an analysis of the article.