Heredity, of course, has a lot to do with how smart your child will turn out. But the environment in which he or she develops is an important factor.
By Laurie Barclay
Reviewed By Cynthia Haines
Can you do anything to make your child smarter -- before he or she is born? Some say it's possible. Here's why they think so.
Nature Versus Nurture
Remember the old "nature versus nurture" debate from biology class? In a nutshell, we're stuck with whatever talents nature gives us, but our environment can nurture -- or hinder -- those gifts.
How important is heredity to intellect?
"Intelligence emerges from the interaction of a person's genetic makeup and the environment in which they develop," Thomas J. Darvill, PhD, tells WebMD. "We have little control over nature's contribution, but the uterine environment is of critical importance and often overlooked by new parents."
Prospective parents with a family history of genetic diseases may benefit from screening and counseling, says Darvill, chairman of psychology and associate director of the Center for Neurobehavioral Effects of Environmental Toxics at Oswego State University in New York.
Biological signs of intelligence suggest, but don't prove, that heredity is an important determinant of IQ, explains Linda Gottfredson, PhD, a professor of education at University of Delaware in Newark.
When it comes to the biological basis of intelligence, size and speed matter. Larger hat size is loosely linked to IQ, although the largest human brain on record belonged to someone with severe mental retardation. Faster reaction time, impulse transmission in nerves, and response of brain waves to unusual sounds are all linked to higher intelligence.
Research by Richard Plomin, PhD, at the Institute of Psychiatry at King's College in London, has identified specific genes predicting high intelligence, reading disability, and mental retardation.
The extent to which genetics accounts for differences in IQ increases with age from about 40% in the preschool years to about 80% in adulthood. "To increase the chances of having a smart baby, marry someone smart!" Gottfredson says.
First, Do No Harm
Perhaps the best practical advice for how to have a smarter baby is not to hinder nature's miracle-in-progress. Even before conception, the mother and probably the father should avoid drugs, alcohol, tobacco, and caffeine, says Stephen J. Schoenthaler, PhD, a professor of nutrition and behavior at California State University in Long Beach.
Brain cells depend on chemical signals to tell them where to go, how to connect, and which genes to turn on or off. "Any foreign substance that interferes with the clear transmission of these chemical messages can impact negatively on development," says Darvill.
While the evidence is most clear-cut for alcohol, pregnant women should avoid all drugs, says Acheson, an assistant professor of psychology at Western Carolina University in Cullowhee, N.C.
"It's commonsense stuff, but I still see incredibly intelligent pregnant women who should know better continuing to smoke," she says.
Less obvious enemies can be equally deadly to the developing brain. One of these is lead from old paint and plumbing. Families living in older homes should have their air and water tested, Darvill says.
Seafood from contaminated waters may harbor brain toxins such as PCBs, methyl mercury, lead, cadmium, and pesticides. Warnings by authorities against eating local fish should be taken seriously by pregnant women, says Philippe Grandjean, MD, professor of environmental health at Boston University School of Public Health. The FDA says moms-to-be should avoid swordfish, king mackerel, tilefish, and other large ocean fish that tend to concentrate toxic chemicals.
Especially during the first trimester, infections like German measles or toxoplasmosis, which is caused by a parasite that can be contracted through contact with infected cat feces, can wreak havoc on the embryonic brain. So pregnant women should stay away from sick children and avoid changing the litter box whenever possible.
Thyroid disease is another culprit that can sneak up unnoticed, says endocrinologist John Lazarus, MD. Babies born to women with low thyroid function are more likely to have low IQ. To determine whether thyroid replacement in similar women might help, his group at the University of Wales College of Medicine in Cardiff has started a seven-year clinical study.
Can you jump-start Junior's brain by playing Mozart through earphones wired to your belly?
No, says Kenneth M. Steele, PhD, an associate professor of psychology at Appalachian State University in Boone, N.C.
"There is no solid scientific evidence that human fetuses either need or benefit from additional stimulation of the 'Mozart-effect' variety," Steele tells WebMD. Sounds entering the fluid-filled womb are muffled and distorted. It's much like hearing the noise of a pool party when your head is under water.
Cranking up the stereo volume could eventually damage the mother's hearing, and transmitting sound directly to the unborn child through earphones could permanently damage the baby's sensitive ears. Steele recommends that pregnant women also avoid prolonged exposure to high intensity sounds, especially those of lower pitch than the human voice: "If it's too loud for the mother then it's probably too loud for the baby."
When you're eating for two, remember that both of you need a whole host of nutrients to support the dramatic changes taking place. As your child travels that amazing journey from single cell to fully developed baby, her brain cells are especially finicky about what they need to achieve their greatest potential.
"Prenatal nutrition for the mother is essential," Schoenthaler tells WebMD. "A supplement is an insurance policy rather than a replacement for good eating."
In addition to a prenatal vitamin/mineral supplement, he recommends five or six daily servings of fruits and vegetables and five of whole grains. As fat and protein are crucial for fetal brain development, total calories should include at least 12% in lean proteins and not more than 30% in fat or 10% in sugar.
Eat More Eggs?
Exciting news from animal research on choline, a substance plentiful in eggs, may have profound implications for developing babies, explains H. Scott Swartzwelder, PhD, a clinical professor of psychiatry at Duke University in Durham, N.C. Nerve cells transform choline into acetylcholine, a chemical messenger involved in memory and lacking in patients with Alzheimer's disease.
When Swartzwelder gave pregnant rats a diet containing three times the usual amount of choline, their offspring did better on maze-learning and similar tests of spatial memory. They also had improved function in the brain region known as the hippocampus, which is vital for memory and learning. Conversely, offspring of rats lacking choline in their diet had fewer connections between nerve cells in the hippocampus and had trouble learning.
Because some women may become choline-deficient during pregnancy and breastfeeding, the Institute of Medicine increased the recommended choline requirement during pregnancy.
"I have three kids, and each time my wife got pregnant, the prenatal vitamin and supplement pill they prescribed for her got larger," Swartzwelder says.
Steven H. Zeisel, MD, professor and chairman of nutrition at the University of North Carolina at Chapel Hill, will be studying the effect of choline-rich diet in about 100 pregnant women, and following the development of their babies over time.
Until the results are in, Swartzwelder sees no harm in most moms-to-be eating more eggs, nuts, meats, and other foods rich in choline. Of course, it's always wise to get your doctor's blessing before changing your diet drastically.
Even more exciting is Swartzwelder's unpublished research suggesting that the rat superstars whose mothers feasted on choline were protected from memory loss in later life. When he gave them a drug known to damage crucial areas of the hippocampus, they had less cell loss than did rats born to mothers fed a normal diet.
"It's really exciting to think that if we make a benign change in the diet of pregnant moms, we might be able to increase the intelligence of our children and even help prevent age-related diseases affecting memory," Swartzwelder says. "It's very fulfilling to me as a scientist to see human trials beginning. When my kids are having kids, maybe we'll know how to make healthier, smarter babies."
Originally published Oct. 8, 2001.
Medically updated February 2005.
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