can be a sign of a neurological disorder. Infants need to be able to do it within five months of birth. It is time limited, though; its persistence beyond five months is also a sign of a neurological disorder.
The Moro demonstrates that a great deal of motor (movement) and vestibular (balance) abilities have already been laid down by eight months. Vestibular abilities allow muscles to be in constant communication with the ears, all coordinated by the brain. You need a fairly sophisticated form of this communication in order to do a Moro.
Babies don’t start off capable of doing full-tilt gymnastics, of course. But they are capable of “quickening,” which is a flutter of embryonic limbs, at about six weeks post-conception, though the mother usually can’t feel anything for another five weeks. This movement is also important. It must occur, or your baby’s joints will not develop properly. By the middle of the third trimester, your baby is fully capable of deliberately commanding her body to perform a coordinated series of movements.
Taste
The tissues that mediate “gustatorial sensations” don’t emerge from your embryo’s tiny tongue until about eight weeks after conception. That doesn’t mean your baby simultaneously acquires the ability to taste something, of course; that doesn’t happen until the third trimester. Once again we see the reception-before-perception pattern of sensory development.
At that point, you can observe some behaviors familiar to all of us. Third-trimester babies change their swallowing patterns when mom eats something sweet: They gulp more. Flavorful compounds from a mother’s diet cross the placenta into the amniotic fluid, which babies in the third trimester swallow at the rate of a quart a day. The effect is so powerful that what you eat during the last stages of pregnancy can influence the food preferences of your baby.
In one study, scientists injected apple juice into the wombs of pregnant rats. When the rat pups were born, they showed a dramatic preference for drinking apple juice. A similar taste preference happens with humans. Mothers who drank lots of carrot juice in the later stages of pregnancy had infants who preferred carrot-flavored cereal. This is called flavor programming, and you can do it soon after your baby is born, too. Lactating mothers who eat green beans and peaches while nursing produce weaned toddlers with the same preferences.
It’s possible that anything that can cross the placenta can incite a preference.
Getting it just right
From touch and smell to hearing and vision, babies have an increasingly active mental life in the womb. What does this mean for parents eager to aid that development? If motor skills are so important, shouldn’t moms-to-be do cartwheels every 10 minutes to induce the Moro reflex in their in utero partners? If food preferences are established in the womb, shouldn’t moms-to-be become vegetarians in the last half of pregnancy if they want their kids to eat fruits and vegetables? And is there an effect, beyond creating potential preferences, of pumping Mozart or Dr. Seuss into your unborn baby’s brain?
It is easy to start making assumptions. So a word of caution. These studies represent the edge of what is known, and it is very easy to over-interpret what the data mean. These are all interesting research questions. But today’s data are not strong enough to solve the mystery of early mental life. They are just enough to reveal it.
The Goldilocks Effect
The biology of infant brain development reminds me of “Goldilocks and the Three Bears.” The classic version of the story describes a young girl with blond hair breaking into and essentially vandalizing a bear family’s vacant hut. She samples and renders judgments over their bowls of porridge, chairs, and beds. Goldilocks doesn’t like Papa Bear’s or Mama Bear’s belongings; the physical characteristics are just too extreme. But Baby Bear’s stuff is “just right,” from temperature to sturdiness to the bed’s cozy comfort. Like so many legendary children’s stories, there are many renditions of this odd little tale. The first published version, by 19th-century poet Robert Southey, had an angry old woman breaking into the bears’ hut and sampling the wares of three male bears. Some literary historians suggest Southey borrowed from the story of Snow White, who breaks into the dwarves’ house, tastes their food, sits on their stools, and then falls asleep on one of their beds. In one early version of “Goldilocks,” the intruder was a fox, not a woman; later she became a girl variously called Silver Hair, Silver-Locks, and Golden Hair. But the “just right” principle is preserved throughout.
So many creatures have this just-right characteristic embedded in their biology that scientists have given the phenomenon its own rather unscientific name: the Goldilocks Effect. It is so common because biological survival in this hostile world often calls for a balancing act between opposing forces. Too much or too little of something, such as heat or water, often hurts biological systems, most of which are obsessed with homeostasis. A full description of many biological processes involves this “just right” idea.
Four things proven to help baby’s brain
The behaviors proven to aid and abet brain development in the womb—especially important in the second half of pregnancy—all follow the Goldilocks principle. We will look at four of these balancing acts:
• weight
• nutrition
• stress
• exercise
And there’s not a pregaphone in sight.
1. Gain just the right weight
You’re pregnant, so you need to eat more food. And if you don’t overdo it, you will grow a smarter baby. Why? Your baby’s IQ is a function of her brain volume. Brain size predicts about 20 percent of the variance in her IQ scores (her prefrontal cortex, just behind her forehead, is particularly prescient). Brain volume is related to birth weight, which means that, to a point, larger babies are smarter babies. The increase slows as baby reaches 6.5 pounds: There is only 1 IQ point difference between a 6.5-pounder and a 7.5-pounder.
The fuel of food helps grow a larger baby. Between four months and birth, the fetus becomes almost ridiculously sensitive to both the amount and the type of food you consume. We know this from malnutrition studies. Babies experiencing a critical lack of nutriment have fewer neurons, fewer and shorter connections between the neurons that exist, and less insulation all around in the second trimester. When they grow up, the kids carrying these brains exhibit more behavioral problems, show slower language growth, have lower IQs, get worse grades, and generally make poor athletes.
How much do you need to eat? That depends upon how fit you are going into the pregnancy. Unfortunately, 55 percent of women of childbearing age in the United States are already too fat. Their Body Mass Index, or BMI, which is a kind of a “gross domestic product” of how fat you are, is between 25 and 29.9. If that’s you, then you need to gain only about 15 to 25 pounds to create a healthy baby, according to the Institute of Medicine. You want to add about half a pound a week in the critical second and third trimesters of pregnancy. If you are underweight, with a typical BMI of less than 18.5, you need to gain between 28 and 40 pounds to optimize your baby’s brain development. That’s about a pound a week in the critical last half of pregnancy. This is true for women of healthy weight, too.
So the amount of fuel is important. There is increasing evidence that the type of fuel you eat during the critical period also is important. The next balance comes between foods that a pregnant mom wants to eat and foods that are optimal for a baby’s brain development. Unfortunately, they are not always the same thing.
2. Eat just the right foods
Women have strange experiences with food preferences during pregnancy, suddenly loathing foods they used to love and craving foods they used to loathe. It’s not just pickles and ice cream, as any pregnant woman can tell you. One woman developed a craving for lemon juice on a burrito—a need that lasted for three months. Another wanted pickled okra. A surprising number crave crushed ice. Women can even desire to eat things that aren’t food. Items that regularly make the Top 10 List of Weird Pregnancy Cravings include baby talcum powder and coal. One woman wanted to lick dust. Pica is a common disorder: a craving lasting longer than a month for eating things that aren’t