LIVING IN THE WOMB AND HEALTH AS CHILDREN AND ADULTS!
THE WOMB - YOUR MOTHER - YOURSELF
Cancer. Heart disease. Obesity, Depression. Scientists can
now trace adult health to the nine months befor birth!!!
by Anne Murphy Paul
Part Two
Continued from previous page
Their metabolisms were, in effect, made normal by their
prenatal experience - perhaps through a process known as
epigenetic modification, in which environmental influences affect
the behavior of genes without altering DNA. It may be that the
intrauterine environment is even more important than genes or
shared eating habits in passing on a propensity for obesity, Kral
says. If that's so, helping women maintain a healthy weight
before and during pregnancy maybe the best hope for stopping
obesity before it starts.
The science of fetal origins also offers hope to people who
believe that heredity has doomed their families to disease people
like the Pima Indians of the Gila River Reservation in Arizona,
who have the highest rate of Type 2 diabetes in the world. There
is little doubt that the high incidence of diabetes among the
Pimas, and among Native Americans in general, has a significant
genetic component. But new research from a study that has
followed a large group of Pima Indians since 1965 points to an
additional influence: prenatal experience. During pregnancy, a
diabetic woman's high blood sugar appears to disrupt the
developing metabolism of the fetus, predisposing it to diabetes
and obesity.
Exposure to maternal diabetes in utero accounts for most of
the increase in Type 2 diabetes among Pima children over the past
30 years, says Dana Dabelea, associate professor of epidemiology
at the University of Colorado at Denver and an investigator on
the study, and it may well be a factor in the alarming rise of
the disease nationally. But it also opens a door to intervention.
"If we could intensively control diabetic women's blood sugar
during pregnancy," Dabelea says, "we could really bring down the
number of children who go on to develop diabetes."
What's more, an understanding of the role of gestational
factors in disease can change individual behavior, notes Daniel
Benyshek, a medical anthropologist at the University of Nevada at
Las Vegas, who has interviewed members of Arizona's Native
American tribes. He finds that those who believe diabetes is
their genetic destiny tend to hold fatalistic attitudes about the
illness. When Benyshek shared findings about the fetal origins of
diabetes with tribe members, however, he noticed a different
reaction. "The idea that some simple changes made during
pregnancy could reduce the offspring's risk for diabetes fosters
a much more hopeful and engaged response," he says. "Young women
in particular are enthusiastic about the idea of intervening in
pregnancy to break the cycle of diabetes. They say, 'I tried
dieting, I tried exercising, and I couldn't keep it up. But I
could do it for nine months if it meant that my baby would have a
better chance at a healthy life.'"
The Impact of Air
THE CHANCE OF A HEALTHIER LIFE IS what Frederica Perera is
trying to give children in some of New York City's struggling
neighborhoods. Perera, the director of the Center for Children's
Environmental Health at Columbia University, became interested in
the effects of pollution on fetuses more than 30 years ago, when
she was conducting research on environmental exposures and cancer
in adults. "I was looking for control subjects to compare to the
adults in my study, individuals who would be completely untouched
by pollution," she says. She hit on the idea of using babies just
out of the womb as her controls, but when she received the
results from samples of umbilical-cord blood and placental tissue
she'd sent to a laboratory to be analyzed, she was sure there had
been a mistake. "I was shocked," she says. "These samples I
thought would be pristine already had evidence of contamination."
Since then, research by Perera and others has tied exposure
to traffic-related air pollution during pregnancy to a host of
adverse birth outcomes, including premature delivery, low birth
weight and heart malformations. One of Perera's most striking
studies got under way in 1998, when more than 500 pregnant women
fanned out across upper Manhattan and the South Bronx wearing
identical black backpacks, which they wore every waking moment
for two days. Inside each backpack was an air monitor
continuously measuring levels of polycyclic aromatic
hydrocarbons, or PAHs, a type of pollutant that comes from
vehicle exhaust and is also present in the fumes released by
cigarettes and factory smokestacks.
The monitors revealed that 100% of the women were exposed to
PAHs during their pregnancies. After their babies were born,
analyses of cord blood from the infants showed that 40% had
subtle DNA damage from PAHs - damage that has been linked to
increased cancer risk. Further analysis found that those exposed
prenatally to high levels of PAHs were more than twice as like-
ly to be cognitively delayed at age 3, scoring lower on an
assessment that predicts performance in school; at age 5, these
children scored lower on IQ tests than children who received less
exposure to PAHs in the womb.
Investigations like these have prompted scientists to expand
their list of populations that are especially vulnerable to
pollution. "We used to worry about elderly people and asthma
patients," Perera says. "Now we worry about fetuses." And efforts
to reduce environmental toxins can make a measurable difference,
she says. "Over the years that we've been tracking exposures, New
York City buses have switched to cleaner technology, and
restrictions have been placed on the idling of diesel buses and
trucks," Perera notes. As a result, we've seen the levels of
pollutants in pregnant women's blood coming down, which means
their fetuses are encountering fewer of these substances too."
The Sources of Stress
AT THE FARTHEST EDGE OF FETAL-ORIGINS research, scientists
are exploring the possibility that intrauterine conditions
influence not only our physical health but also our intelligence,
temperament, even our sanity. Evidence indicates, for example,
that pregnant women subjected to starvation or extreme stress
give birth to children with a higher risk of schizophrenia.
Schizophrenia is a complex disorder with many potential causes.
But a study based on 30 years of case records from Anhui province
in China strongly suggests that prenatal factors can play a role.
In the mid-20th century, residents of that region experienced
severe malnutrition during the famine that accompanied the Great
Leap Forward, Mao Zedong's disastrous modernization campaign.
Individuals born to women suffering from the famine were twice as
likely to develop schizophrenia as those gestated at other times.
Likewise, a study of the health records of more than 88,000
people born in Jerusalem between 1964 and 1976 found that the
offspring of women who were in their second month of pregnancy in
June 1967 - the time of the Arab-Israeli Six-Day-War - were
significantly more likely to develop schizophrenia as young
adults.
Catherine Monk, an assistant professor of psychiatry at
Columbia University, has advanced an even more startling
proposal: that a pregnant woman's mental state can shape her
offspring's psyche. "Research indicates that even before birth,
mothers' moods may affect child development," Monk says. "Can
maternal mood be transmitted to the fetus? If so, what is the
mode of transmission? And how do such moods affect fetal
development? These are new questions to be asking," she says.
"We're still figuring out how to get fetuses to answer."
In fact, Monk and her colleagues have gone some way toward
putting the fetus on the couch. At her lab, pregnant women who
are depressed or anxious and pregnant women with normal moods are
hooked up to devices that measure their respiration, heart rate,
blood pressure and nervous system arousal, as well as the
movements and heart rate of their fetuses, and then subjected to
challenging mental exercises. All of the women show physiological
signs of stress in response to the tests, but only the fetuses of
depressed or anxious women display disturbances of their own.
"This difference suggests that these fetuses are already more
sensitive to stress," Monk says. "Perhaps that's because of a
genetic predisposition inherited from the parents. Or it could be
because the fetuses' nervous systems are already being shaped by
their mothers' emotional states." Women's heart rate and blood
pressure, or their levels of stress hormones, could affect the
intrauterine milieu over the nine months of gestation, Monk
explains, influencing
......
To be continued
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