Thursday, July 17, 2008

A Sniffly Penalty for Parenting "Right"

Photo by Flickr user James Jordan, used under a Creative Commons license.

So you had a baby. You breastfed for a year (well, ten months, because he was losing interest and you were ready to get your body back). And you waited until he's six months to introduce solid food (well, five months, because he was watching your spoon move with such lust!). And you did all of this "right" - well, by the book, anyway - because your baby's dad has wretched allergies and you wanted to spare him the same fate.

And now? It turns out you did it all wrong:
Delayed introduction of cow's milk and other food products is associated with a higher rather than lower risk for atopic manifestations in the first 2 years of life, epidemiologists in the Netherlands report in the July issue of Pediatrics.

They note that one of the most widely recommended allergy prevention strategies is delaying the introduction of milk and solid foods into the infant's diet. However, there is little scientific evidence to support this advice.

To investigate, Dr. Bianca E. P. Snijders, at Maastricht University, and her colleagues analyzed data from a prospective birth cohort of 2558 infants. Mothers completed questionnaires at 34 weeks of gestation and at 3, 7, 12, and 24 months postpartum regarding food exposures, allergy manifestations, and confounders. Blood samples were collected from the infants at 2 years of age for determination of sensitization.

After adjustment for duration of breastfeeding, sex, exposure to tobacco smoke, maternal characteristics, and family history of allergy, delay in the introduction of cow's milk products beyond 9 months significantly increased the risk of eczema (adjusted odds ratio 2.29).

(Source: Reuters Health via Medscape, free registration required; article also available at without registration; the study is published in Pediatrics 2008;122:e115-e122.)
Translating back from science-ese: Wait too long to diversify your kid's diet and you could more than double his or her chances of living with allergies.

Of course breastfeeding is still a good thing. But women have been made to feel guilty for introducing solid foods "too soon" and for not "exclusively" breastfeeding for "long enough." All of those are spongy terms that seem to shift with the winds of changing medical fashion.

That baby of mine - the one who watched my spoon like a tennis match - was the Bear. He's had the sniffles this week. I've wondered if he might be showing some mild allergies, since he didn't otherwise seem sick. I still don't know. But at least now I'll stop wondering if his sniffles has any relation to those carrots that he wore so cutely all over his face as a plump and happy five-month-old. Of course, he wanted them earlier. Maybe he was right?

It's funny how I wrote nearly a hundred pages in my dissertation on what a crock "expert" advice can be - and yet I'm one of the biggest suckers for it.


Smirking Cat said...

I can't stand to see the conclusions of a study published but not the methodology, sample size and demographics, things that help you draw your own conclusions and identify potential weaknesses of a study. The "experts" make mistakes too, and people would do themselves a favor to understand at least the basics of research methods instead of "Oh, a scientist said this", but having no idea how that scientist came to his or her conclusion.

How many magazines and newspapers do you see that report the findings ("Scientists say...") then fail to tell you how they determined their findings?

Sungold said...

You're right, it's rare that science reporting gives you enough detail. I didn't trace this news item back to its source - although since I have access to a university library and its electronic journal holdings, I'm usually able to do so. (I'm lazy this week because I'm pressed for time - just got to Berlin and need to get the apartment set up for five weeks - and the jet lag is just hammering me!)

Just on the face of it, though, I could point out that the Netherlands is not the U.S., and so that alone may limit our ability to generalize the study.

I do think this is a fairly robust study, however. The sample size is fairly large, it was prospective (so didn't rely on people's faulty memories, though obviously people don't always give accurate self-reports), and it used blood testing to determine allergy sensitization.

I'd love to see Americans become more scientifically literate - if we all demanded better science journalism, we *might* get it. As it is, most people just throw up their hands and say, oh, those studies always contradict each other. Most people have little basis for judging the quality of a study. And that makes people gullible.