NEW YORK - Children whose mothers took antibiotics while they were
pregnant were slightly more likely than other kids to develop asthma in
a new Danish study.
The results don't prove
that antibiotics caused the higher asthma risk, but they support a
current theory that the body's own "friendly" bacteria have a role in
whether a child develops asthma, and antibiotics can disrupt those
beneficial bugs.
"We speculate that mothers' use
of antibiotics changes the balance of natural bacteria, which is
transmitted to the newborn, and that such unbalanced bacteria in early
life impact on the immune maturation in the newborn," said Dr. Hans
Bisgaard, one of the authors of the study and a professor at the
University of Copenhagen.
Those effects on the
immune system could lead to asthma later on, although it's still not
clear how, said Anita Kozyrskyj, a professor at the University of
Alberta who also studies the antibiotics-asthma link but wasn't involved
in the new study.
Previous research has linked
antibiotics taken during infancy to a higher risk of asthma, although
some researchers have disputed those findings.
To look for effects starting at an even earlier point in a baby's
development, Bisgaard and his colleagues gathered information from a
Danish national birth database of more than 30,000 children born between
1997 and 2003 and followed for five years.
They
found that about 7,300 of the children, or nearly one quarter, were
exposed to antibiotics while their mothers were pregnant. Among them,
just over three percent (238 kids) were hospitalized for asthma by age
five.
In comparison, about 2.5 percent, or 581
of some 23,000 kids whose mothers didn't take antibiotics were
hospitalized for asthma.
After taking into
account other asthma risk factors, Bisgaard's team calculated that the
children who had been exposed to antibiotics were 17 percent more likely
to be hospitalized for asthma.
Similarly, these
children were also 18 percent more likely to have been given a
prescription for an asthma medication than kids whose mothers did not
take antibiotics when they were pregnant, according to findings
published in The Journal of Pediatrics.
In an
email to Reuters Health, Bisgaard said he expected to see a higher risk
of asthma "because the mother is a prime source of early bacterial
colonization of the child, and antibiotics may (have) disturbed her
normal bacterial flora."
Bisgaard's team also
looked at a smaller group of 411 kids who were at higher risk for asthma
because their mothers had the condition and found these children were
twice as likely as their peers to develop asthma too if their mothers
took antibiotics during the third trimester of pregnancy.
Kozyrskyj, who is research chair of the Women and Children's Health
Research Institute, said it's also possible that something other than
the antibiotics are to blame for the findings in both groups of
children—such as the illness that caused the mothers to take
antibiotics.
"This study, it doesn't tell us
whether it's the antibiotic use or whether it's the infection. That's
one thing we can't decipher," she told Reuters Health.
The results don't suggest that women should avoid taking antibiotics to
try to reduce their kids' risk of asthma, Kozyrskyj emphasized.
Some infections can be quite dangerous to a fetus, and "there are very good indications for these antibiotics," she added.
Bisgaard agreed that women should be treated, "but we see 1/3 of
pregnant women in our region receiving treatments (often for urinary
tract infections), which may reflect an uncritical use," he wrote in an
email.
Bisgaard said his group is also studying
the types of bacteria in pregnant mothers and newborn children to get a
better understanding of their role in asthma.
Kozyrskyj said Bisgaard's study suggests that the development of asthma
might start before birth, something researchers hadn't studied very
closely.
"We're beginning to appreciate that
some of the origins of asthma and changes to the immune system, maybe
they start earlier than right after birth. It might be happening in
utero," she said. –Reuters
0 comments:
Post a Comment