Fetal Psychology

Your baby can feel, dream and even listen to Mozartin the womb.

By Janet L. Hopson, published on September 01, 1998 - last reviewed on August 30, 2004

DeCasper and others have uncovered more mental feats. Newborns can not only distinguish their mother from a stranger speaking, but would rather hear Mom's voice, especially the way it sounds filtered through amniotic fluid rather than through air. They're xenophobes, too: they prefer to hear Mom speaking in her native language than to hear her or someone else speaking in a foreign tongue.

By monitoring changes in fetal heart rate, psychologist JeanPierre Lecanuet and his colleagues in Paris have found that fetuses can even tell strangers' voices apart. They also seem to like certain stories more than others. The fetal heartbeat will slow down when a familiar French fairy tale such as "La Poulette" ("The Chick") or "Le Petit Crapaud" ("The Little Toad") is read near the mother's belly. When the same reader delivers another unfamiliar story, the fetal heartbeat stays steady

The fetus is likely responding to the cadence of voices and stories, not their actual words, observes Fifer, but the conclusion is the same: the fetus can listen, learn, and remember at some level, and, as with most babies and children, it likes the comfort and reassurance of the familiar.

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FETAL PERSONALITY

It's no secret that babies are born with distinct differences and patterns of activity that suggest individual temperament. Just when and how the behavioral traits originate in the womb is now the subject of intense scrutiny.

In the first formal study of fetal temperament in 1996, DiPietro and her colleagues recorded the heart rate and movements of 31 fetuses six times before birth and compared them to readings taken twice after birth. (They've since extended their study to include 100 more fetuses.) Their findings: fetuses that are very active in the womb tend to be more irritable infants. Those with irregular sleep/wake patterns in the womb sleep more poorly as young infants. And fetuses with high heart rates become unpredictable, inactive babies.

"Behavior doesn't begin at birth," declares DiPietro. "It begins before and develops in predictable ways." One of the most important influences on development is the fetal environment. As Harvard's Als observes, "The fetus gets an enormous amount of 'hormonal bathing' through the mother, so its chronobiological rhythms are influenced by the mother's sleep/wake cycles, her eating patterns, her movements."

The hormones a mother puts out in response to stress also appear critical. DiPietro finds that highly pressured mothers-to-be tend to have more active fetuses--and more irritable infants. "The most stressed are working pregnant women," says DiPietro. "These days, women tend to work up to the day they deliver, even though the implications for pregnancy aren't entirely clear yet. That's our cultural norm, but I think it's insane."

Als agrees that working can be an enormous stress, but emphasizes that pregnancy hormones help to buffer both mother and fetus. Individual reactions to stress also matter. "The pregnant woman who chooses to work is a different woman already from the one who chooses not to work," she explains.

She's also different from the woman who has no choice but to work. DiPietro's studies show that the fetuses of poor women are distinct neurobehaviorally-less active, with a less variable heart rate--from the fetuses of middle-class women. Yet "poor women rate themselves as less stressed than do working middle-class women," she notes. DiPietro suspects that inadequate nutrition and exposure to pollutants may significantly affect the fetuses of poor women.

Stress, diet, and toxins may combine to have a harmful effect on intelligence. A recent study by biostatistician Bernie Devlin, of the University of Pittsburgh, suggests that genes may have less impact on IQ than previously thought and that the environment of the womb may account for much more. "Our old notion of nature influencing the fetus before birth and nurture after birth needs an update," DiPietro insists. "There is an antenatal environment, too, that is provided by the mother."

Parents-to-be who want to further their unborn child's mental development should start by assuring that the antenatal environment is wellnourished, low-stress, drug-free. Various authors and "experts" also have suggested poking the fetus at regular intervals, speaking to it through a paper tube or "pregaphone," piping in classical music, even flashing lights at the mother's abdomen.

Does such stimulation work? More importantly: Is it safe? Some who use these methods swear their children are smarter, more verbally and musically inclined, more physically coordinated and socially adept than average. Scientists, however, are skeptical.

"There has been no defended research anywhere that shows any enduring effect from these stimulations," asserts Filer. "Since no one can even say for certain when a fetus is awake, poking them or sticking speakers on the mother's abdomen may be changing their natural sleep patterns. No one would consider poking or prodding a newborn baby in her bassinet or putting a speaker next to her ear, so why would you do such a thing with a fetus?"

Als is more emphatic. "My bet is that poking, shaking, or otherwise deliberately stimulating the fetus might alter its developmental sequence, and anything that affects the development of the brain comes at a cost."