Of interest?  This was in Medscape today.  And it 
seems to show the _opposite_ of what I've always 
understood, which is that (at least for breastfed 
babies) there is a higher risk of 
allergy/sensitivity with increased birth order.  Comments, anyone?

http://www.medscape.com/viewarticle/739587?sssdmh=dm1.675114&src=nldne 
(you have to be subscribed to access this ...)
 From WebMD Health News
Birth Order May Affect Risk of Allergies

Jennifer Warner

March 21, 2011 — First-born children may be more 
likely to develop certain types of allergies than 
their younger brothers or sisters, a study suggests.

Researchers found the prevalence of several types 
of allergies, such as allergic rhinitis (hay 
fever or seasonal allergies), allergic 
conjunctivitis (eye inflammation due to 
allergies), and food allergy decreased as birth 
order increased in a large group of Japanese schoolchildren.

For example, 4% of first-borns had some type of 
food allergy compared with 3.5% of second-borns and 2.6% of third-borns.

Researchers say it's the first study to show an 
effect of birth order on food allergy.

Benefit of Being the Youngest

Researchers surveyed the parents of more than 
13,000 schoolchildren in Japan aged 7 to 15 about 
the prevalence of specific allergic diseases.

Based on the results, researchers calculated the 
prevalence of each allergic disease based on birth order.

The results showed there was no significant 
difference in the prevalence of asthma or atopic 
dermatitis (a type of eczema) according to birth order.

But the prevalence of allergic rhinitis, allergic 
conjunctivitis, and food allergy decreased based 
on birth order -- from oldest to youngest.

“Individuals with increased birth order have a 
smaller risk of allergy," explained Takashi 
Kusunoki, MD, PhD, of the Shiga Medical Center 
for Children in Moriyama, Japan, in a news 
release. "However, the significance of the effect 
may differ by allergic diseases.”

Prenatal Origins of Allergies?

The study also showed that in infancy symptoms 
such as wheezing increased and food allergies 
decreased as birth order increased.

Researchers say these findings suggest that food 
allergies may have their origins in the prenatal period in the womb.

The results were presented at the Annual Meeting 
of the American Academy of Asthma, Allergy and Immunology in San Francisco.

This study was presented at a medical conference. 
The findings should be considered preliminary as 
they have not yet undergone the "peer review" 
process, in which outside experts scrutinize the 
data prior to publication in a medical journal.

SOURCES:

Annual Meeting of the American Academy of 
Allergy, Asthma & Immunology, San Francisco, March 18-22, 2011.

News release, American Academy of Allergy, Asthma & Immunology.
-------------------

Pamela Morrison IBCLC
Rustington, England 

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