This expands on the original post to say no link with the 3rd trimester.
Also, I can't find it today, but another article said that Kaiser also
discounted asthma drugs as the cause.

Allergies, Asthma May Play Role in Autism

Tuesday, February 08, 2005

By Salynn Boyles

Allergies or asthma during pregnancy may increase the risk of giving birth
to a child who develops autism.

Investigators caution that the association must be confirmed, and that the
increase in risk observed in a study was quite small. The findings are
reported in the February issue of the Archives of Pediatrics and Adolescent
Medicine.

"This is a modest effect, and it is the first time, to my knowledge, that it
has been reported," lead researcher Lisa A. Croen, PhD, of the Kaiser
Foundation Research Institute, tells WebMD. "These findings certainly need
to be replicated. But this gives us some interesting clues to pursue."

Second Trimester Riskiest

The researchers also investigated, but failed to find, a link between autism
and a family history of autoimmune diseases like lupus, type 1 diabetes and
rheumatoid arthritis. Earlier studies had suggested such a link, but most
relied on self-reported data.

Autoimmune disorders occur when the body mistakenly attacks normal tissues
as if they were foreign.

Croen and colleagues examined the medical records of more than 88,000
children born between 1995 and 1999 in Northern California. Of these
children, 420 were later identified as having autism or a related disorder.
These cases were compared to 2,100 nonautistic children of similar sex, age
and birth hospital.

The researchers found that expectant mothers with asthma diagnosed in the
second trimester were twice as likely to have a child that developed autism.
The researchers found no risk among women found to have asthma during the
third trimester.

The risk was smaller for women with allergies. The only significant effect
was for women diagnosed with allergies in the second trimester. These women
were 2.5 times as likely to have a child that developed autism.

Clues About Where to Look Next?

Although the causes of autism are not well understood, genetic
predisposition is considered to play a major role. A few environmental
triggers have also been identified, including prenatal exposure to certain
chemicals.

Andy Shih, PhD, tells WebMD that what we now lump together as autism is
likely to end up being several related, but distinct disorders. Shih is
chief science officer for the National Alliance for Autism Research.

He says the newly published study is the first to look at the issue of
autoimmune disorders and autism in an objective way. He agreed, however,
that the findings are far from conclusive.

"This study does provide a tantalizing clue about a potential mechanism for
autism," he says. "But the cautionary tone of the paper needs to be
emphasized. We don't really know if these findings will hold up to further
scientific scrutiny."

Shih says a larger study with a more comprehensive methodological approach
is needed to better understand the potential link between allergies, asthma
and autism.

"I think this does provide a suggestion about where we should look next," he
says.

By Salynn Boyles, reviewed by Michael W. Smith, MD

SOURCES: Croen et al., Archives of Pediatrics and Adolescent Medicine,
February, 2005; Vol. 159: pp. 151-157. Lisa Croen, PhD, Division of
Research, Kaiser Foundation Research Institute, Oakland, Calif. Andy Shih,
PhD, chief science officer, National Alliance for Autism Research.

Joy