For those who say you're never too young to learn, try typing "smart baby" into YouTube. It may give you some doubts.
You'll find plenty of brainy babies who will dazzle you with geography and other skills, their parents pushing them every step of the way. But you might find yourself thinking there is such a thing as too young to learn.
Monique Heller, of Essex, Conn., is nine months pregnant. She's already started trying to teach her new baby... before the new daughter is even born.
"I want to give her every advantage that we're able to," said Heller. "And to a certain extent, I want her to be prepared for school as early as possible."
Heller uses a device called Baby Plus, marketed as a "prenatal education system." The motto: "Your womb ... the perfect classroom."
"I used it in my pregnancy with my daughter Giovanna," said Heller. "And I'm using it now with my second daughter. And the product claims to help babies self-soothe and come out of the uterus a little more calm."
Heller insists it worked for her first daughter. So why not for daughter No. 2? The device straps right onto the mother's belly, for one hour, twice a day.
Baby Plus spokeswoman Lisa Jarrett explained how the device works.
"It plays a sound that is simple and similar to the maternal placental heartbeat. And that encourages a child to discriminate. That discrimination over time strengthens learning skills for life."
Proponents of the device claim it leads to babies that nurse more readily, that soothe themselves, that are more interactive and responsive, more relaxed and more ready for school.
"Ninety-seven percent of parents who utilize this curriculum would use it again, recommend it to a friend, and feel that it has made a difference," said Jarrett.
'I'm Sorry That's Just Crazy'
But Janet DiPietro, a developmental psychologist at Johns Hopkins University, says there's no evidence whatsoever that products like Baby Plus actually help a developing fetus.
"I'm sorry, that's just crazy," she said, laughing. "Nobody buys it. No scientist studying the fetus buys it."
Scientists are likewise skeptical that the fetal brain benefits from so-called educational stimulus.
"Just because fetuses respond to something doesn't mean that they are learning it," said DiPietro. "Or that it's important to give that sound. So what fetuses seem to respond to most are loud sounds: the vacuum cleaner, a rock concert. And just because they might get kind of jazzed up to one of those things doesn't mean it's either good or bad for them. They just react to it."
"Nightline" pointed out that the notion that you can boost your baby's intelligence, maybe by playing a little Mozart, has been around for awhile.
"Yup, it's been around forever," said DiPietro. "It's absolutely untrue."
We asked DiPietro if the term "prenatal education" makes sense to her.
"No, I cringe," she said. "I absolutely cringe. I don't know anybody in the scientific fetal research world -- all of us who love the prenatal period, and think it's fascinating and holds great implications for later development -- that thinks trying to teach fetuses is a good idea. ... There are no studies that say it's good. There are none."
We asked Jarrett if there were any studies to back up her product's claims.
"Yes," she said, "there's a study that was published in the Preimparnatal Psychology Journal. It was small. My experience has been with the anecdotal evidence. ... It's been studied. It's just not been studied in long-term huge clinical trials. ... There's one early study... [by] Dr. Brent Logan ... and a developmental specialist in Russia. And it was years ago."
Why didn't it get studied here?
"Well, we are trying," said Jarrett. "We are trying."
Of course, that hasn't stopped them from selling the Baby Plus. They cost $149 each. This year, the company plans to sell 20,000 of them.
And Baby Plus is just one of a growing number of products making similar claims, trying to cash in on parents who are interested in fetal development.
'I Think He's Dancing!'
Katherine Kranenburg is a middle-class mom in Washington who, like every mom, wants to give her kids every advantage. She has a 2-year-old, Kennedy. And Kennedy's little brother -- not yet born -- already has a teddy bear that plays the sound of a mother's heartbeat.
"We just got it today," said Kranenburg. "We got the latest high chair. Kind of the Jetsons of highchairs."
Kranenburg said she also does prenatal yoga. And she agreed to try out another brainy baby product, made in Israel, called the Ritmo. It hooks up to your iPod, so that mom can play tunes right into her belly.
Kranenburg played Bob Marley. And sure enough, the fetus responded.
"He's responding by kicking," she said. "I think he's dancing! ... He's kicking. I think he's like, 'What's this? This is kinda fun!'"
But our expert at Johns Hopkins was dubious about the Ritmo, too, because, she says, all that fluid in the mother's belly doesn't muffle the sound -- it amplifies it.
"Which is counterintuitive to most people," DiPietro said. "Because as it goes through the amniotic fluid, the sound gets more intense, not less intense. So when you take these devices and you put them on your abdomen, you're blasting sound at the ear. ... You're taping their head to the speaker. It's akin to taking your sleeping newborn -- because fetuses are mostly asleep -- and putting speakers right next to their crib and blasting Mozart while they're asleep. ... Who would do that?"
DiPietro says it isn't just that these products won't help make your baby brainier. She worries they could actually cause harm.
The manufacturers insist they are safe.
Ritmo's manufacturer says its device "works through a sophisticated controller to regulate the output of sound to a level safe for a baby in-utero."
But it may surprise expecting mothers to learn that you have to take their word for it. The government does not require them to meet any special product safety standards.