[Paleopsych] WSJ: Grandma's Behavior While Pregnant Affects Her Grandkids' Health
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Mon May 16 20:20:49 UTC 2005
Grandma's Behavior While Pregnant Affects Her Grandkids' Health
The Wall Street Journal
May 13, 2005; Page B1
[Thanks to Louis for this.]
Although life offers no guarantees, parents-to-be can increase their chances of
having a healthy baby by, among other things, undergoing prenatal testing and
making sure mom has a healthy pregnancy. But almost 2,500 years after Euripides
noticed that "the gods visit the sins of the fathers upon the children,"
scientists are discovering that nature can be even crueler than the ancient
Greek imagined: It can visit the sins of the grandparents on the children.
Such "transgenerational" effects are the latest focus of a growing field called
fetal programming, or the fetal origins of adult diseases. It examines how
conditions in the womb shape physiology in a way that makes people more
vulnerable decades later to cardiovascular disease, diabetes, immune problems
and other illnesses usually blamed on genetics or lifestyle, not on what
arrived via the placenta. If a fetus is poorly nourished, for instance, it can
develop a "thrifty phenotype" that makes it really good at getting the most out
of every meal. After birth, that lets it thrive if food is scarce, but it's a
recipe for Type 2 diabetes in a world of doughnuts and fries. Poor fetal
nutrition can lead to hypertension, too: If it causes the fetus to produce too
few kidney cells, the adult that the fetus will become won't be able to
regulate blood pressure well.
Now, in a finding that seems to put our fate even further outside our control,
researchers are seeing generation-skipping effects.
Last month, scientists reported that a child whose grandmother smoked while
pregnant with the child's mother may have twice the risk of developing asthma
as a child whose grandma didn't flood her fetus with carcinogens. Remarkably,
the risk from grandma's smoking was as great as or greater than from mom's.
Kids whose mothers smoked while pregnant were 1.5 times as likely to develop
childhood asthma as children of nonsmoking moms. Kids whose grandmothers smoked
while pregnant with mom were 2.1 times as likely to develop asthma, scientists
reported in the journal Chest.
The harmful effects of tobacco, it seems, can reach down two generations even
when the intervening generation -- mom -- has no reason to suspect her child
may be at risk.
"Even if the mother didn't smoke, there was an effect on the grandchild," says
Frank Gilliland of the University of Southern California, Los Angeles, who led
the study of 908 children. "If smoking has this transgenerational effect, it's
a lot worse than we realized."
What causes the grandma effect? One suspect is DNA in the fetus's eggs (all the
eggs a girl will ever have are made before birth). Chemicals in smoke might
change the on-off pattern of genes in eggs, including genes of the immune
system, affecting children who develop from those eggs. Men whose mothers
smoked don't seem to pass on such abnormalities, probably because sperm are
made after birth.
Animal data hint at other grandma effects. Last week, scientists reported the
first discovery that obesity and insulin resistance, as in Type 2 diabetes, can
be visited on the grandkids of female rats that ate a protein-poor diet during
pregnancy, lactation or both. Again, this occurred even when those rats'
offspring, the mothers of the affected grandkids, were healthy, Elena Zambrano
of the Institute of Medical Sciences and Nutrition, Mexico City, and colleagues
report in the Journal of Physiology.
The findings, says Peter Nathanielsz of the University of Texas Health Sciences
Center, San Antonio, "stretch the unwanted consequences of poor nutrition
In people, the type of "nutritional insult" to the fetus doesn't seem to
matter. Too few calories, too little protein, too few other nutrients can all
lead to diabetes, hypertension and other ills decades later. "That suggests
that what links diet to adult diseases is something quite fundamental," says
Simon Langley-Evans of the University of Nottingham, England. The key suspects:
changes in DNA activity in the fetus or in the balance of hormones reaching it
via the placenta.
Alarmingly, the list of what can be passed along to the next generation is
growing. If you are undernourished as a first-trimester fetus, you won't pad
your hips and thighs with enough fat tissue. If, as a child or adult, you take
in more calories than you expend, the extras get stored in and around abdominal
organs rather than on the thighs and hips, says Aryeh Stein of Emory
University, Atlanta. One result is a body shaped like an apple (which brings a
higher risk of heart disease). Another is a higher risk of gestational
diabetes, in which blood glucose levels rise during pregnancy and too much
glucose reaches the fetus. Babies born to moms with gestational diabetes have a
higher risk of Type 2 diabetes.
When undernourished fetuses grow into adolescents, they don't respond as well
to vaccines as babies who had a healthy gestation, scientists led by Thomas
McCune of Northwestern University, Evanston, Ill., find. One reason may be that
the third trimester is a critical time for development of the thymus, which
produces the immune system's T cells. When immune-compromised girls become
pregnant, they have less chance of having a healthy pregnancy and a healthy
baby. Score another for the grandma effect.
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