Iskandar: Hello, I'm Dr. John Iskandar,
welcome to CDC Beyond the Data.
I'm here today with Dr. Allen Mitchell,
Director of the Sloan Epidemiology Center
at Boston University.
Allen, today we heard at the Grand Rounds session
about advances in preventing birth defects.
And, at both a public health and a societal level,
what's the importance of birth defects
and birth defect prevention?
Mitchell: Well, first let's talk about birth defects themselves,
which occur in about one in thirty three pregnancies,
so it's a fairly common complication of pregnancy.
And, among the category of birth defects are a wide variety
of specific birth defects.
We think of congenital heart problems, we think of problems
of the abdominal wall and so forth.
But together, it accounts
for about a 120 thousand babies born each year
with a birth defect.
And, I think that over time, because birth defects have been
with us for so many centuries, people have, sort of,
come to think of them
as an unavoidable consequence of being pregnant.
When in fact research has recently shown in the last,
maybe, thirty, forty,
fifty years that some birth defects are actually avoidable.
And, that's where the research function comes in.
Iskandar: So, moving from simply counting birth defects
to making some advances in prevention,
I know many of our viewers may have been familiar with the,
we're talking terms of the thalidomide tragedy of the 1960s
where pregnant women taking thalidomide had babies
with often serious limb defects.
What have we learned through research since then
about prevention of birth defects?
And what are some of the gaps that remain?
Mitchell: That's a good question.
The thalidomide debacle in the 60s, really as you said,
brought public attention to the problem.
But in fact, it was in the 1940s when we first learned
that the placenta, which we used to think,
would protect the fetus from any kind of environmental problem.
It turns out that congenital rubella, or German measles,
was identified in the 40s
and that was the first time something
like an infection was shown
to increase the risk of birth defects.
The thalidomide example showed us
that medications could also cross the placenta
and medications could also cause devastating birth defects
in certain circumstances.
So that really began the era of attention being focused
on whether there were in fact other agents in environment
that might increase the risk of birth defects.
And, so by avoiding those agents women could presumably reduce
their risk of having a baby with a birth defect.
Iskandar: So one of the things that you've studied
through VAMPS or the vaccines and medications
in pregnancy surveillance system,
is whether there might be medication or other types
of exposures that could increase the risk of birth defects.
Could you tell us a little bit about what that system is?
What its goals are?
And, what some of its findings have been so far?
Mitchell: Sure.
VAMPS was designed specifically, as you point out,
to examine the risks, or relative safety
of medication taken in pregnancy and that includes vaccines.
So our focus has been on the wide range of medications
and vaccines but our particular focus has been on vaccines
or medications that might be used
in a public health emergency.
And, a good example of that was the 2009
and 2010 pandemic with the H1N1 virus.
That was a situation where the government anticipated there
would be a pandemic and they asked the VAMPS team
to study the safety of the vaccine and the medications
that might be used, the antiviral medications
that might be used to prevent or treat influenza.
Mitchell: Some of our findings which were available only months
after the epidemic was over, revealed from the standpoint
of birth defects, that there was no increased risk
for birth defects in general.
And, the vaccine also didn't increase the risk
of specific birth defects.
Iskandar: So I think that's a very important answer
because it provided, you know, reassuring evidence
of the safety of the pandemic influenza vaccine in pregnancy
in a very timely manner.
More broadly than just medications and vaccines,
what are some other environmental exposures
that we're now learning about that are associated
with birth defects and particularly ones
that might be controllable or preventable?
Mitchell: And, that's a very important focus is
that certain causes of birth defects
and the vast majority are unknown
and we'll talk more about that I hope.
But, there are certain causes
which by controlling the causes we can reduce the risk
of birth defects and prominent among those are obesity,
which as everyone knows has increased fairly dramatically
in the United States.
And, pre-gestational diabetes or diabetes
that are present before pregnancy.
That. Those two factors, along with smoking are known
to increase the risk of birth defects.
By controlling obesity, by controlling blood sugar
and certainly by reducing smoking we can make substantial
reductions in the number of the children
who are born with birth defects.
Iskandar: So I think that's a very important perspective
in that it, you know we were earlier talking
about medications and their potential to increase risk
for birth defects but the underlying diseases themselves
is better controlled, such as diabetes may result
in prevention of birth defects.
So, what are those next frontiers
in birth defects prevention?
Mitchell: Well, it's interesting that when I started
out in this field which was quite a while ago,
the idea that some agent could actually reduce the risk
of birth defects.
We knew about infections, we knew about certain medications
but the idea that something simple might actually reduce the
risk of birth defects was unheard of.
But research, and again research in the area of birth defects,
identified about 30 years ago that a simple B vitamin,
folic acid, could dramatically reduce the risk of spina bifida
and other defects of the spinal cord called neural tube defect.
And so we're hopeful that the horizon
for birth defects prevention includes both identifying other
causes and if we're lucky identifying other factors
which might if taken, such as a B vitamin, reduce the risk
of birth defects themselves.
Iskandar: Thank you very much for being with us today, Allen.
Please join us again next month for another episode
of CDC's Beyond the Data.