Your Baby from Birth to 3 Months
There's more to your newborn baby than meets the eye. Here's what's going on inside his head.
Welcome to Your Baby!
Does anyone really know what a newborn baby is capable of? In the early days and weeks after birth, to the naked eye, not much. Eating, crying, sleeping, and pooping seem to take up the majority of her day, with a few moments of alertness thrown in for good measure. But recent research has shown that she's doing a lot more than that. "Even in the first minutes of life, babies are a wonder," says Naomi Steiner, MD, a developmental and behavioral pediatrician at Tufts-New England Medical Center, in Boston. "The newborn has a superactive brain and is primed to learn."
Recent research, much of which relies on high-tech advances in intrauterine photography and brain imaging, now offers empirical proof of what parents have known all along: Babies are smart. What's more, each baby is born with a unique personality that becomes readily apparent within the first few weeks of life. "Babies come into the world as themselves," says Dr. Steiner. "It's our job to get to know them."
Your Infant's Brain & Development
We leave our mother's womb when we're ready. But when a human baby arrives in the world, she is far from finished. Compare a human newborn to a puppy: An 8-week-old puppy runs, plays, eats, and drinks on his own; a human baby of the same age can barely see and can't control her arms and legs. Why? The newborn nervous system and brain are only partly developed, says Dr. Steiner, and the brain is the central command center for the rest of the body. At birth, a baby's brain weighs only a quarter of an adult's brain. It's capable of controlling his most vital functions, such as breathing, crying, sleeping, and feeding. However, the cerebral cortex -- the area of the brain that controls more sophisticated thinking and emotions -- is still growing and developing to allow him to act in accordance with his will rather than simply react to his environment.
So how does a newborn go from a helpless bundle to a laughing, learning infant? At birth, a baby has 100 billion neurons (brain cells). But neurons alone don't spur growth and abilities. In order for baby to get the hang of everything from tracking an object with his eyes to smiling, those brain cells need to connect with one another, sprouting long dendrites, which form bridges between cells. These brain-cell connections are called synapses. When baby is born, he doesn't have many synapses, which is yet another reason he's unfinished: An infant's brain transmits information about 16 times more slowly than an adult's. Speeding up that transmission takes time, too; at birth, your newborn's brain cells are only beginning to develop myelin, a dense, fatty substance that accelerates connections. In the first 3 months of life alone, your baby's brain synapses will multiply more than 20 times.
Your Role in Baby's Brain Development
But your baby's "finishing touches" don't just happen automatically. New research confirms that brain development is "activity-dependent." Every experience your baby has -- from staring at that black-and-white mobile you hang over the crib to learning that cries bring food or comfort -- excites certain neural circuits and leaves others inactive. So what does all this mean to a parent? You needn't break out the flash cards. Talking to your baby, rocking him -- all of the normal parent-child interactions that occur in early life -- contribute to brain growth and make baby smarter.
According to T. Berry Brazelton, MD, professor of pediatrics at Harvard University and author of dozens of parenting books, the most important reason our brains aren't fully formed at birth is that humans are social beings who live and work together in a community. "Individuality isn't as important to a puppy or a giraffe as it is to humans," says Dr. Brazelton. "Our individual differences would be at risk if we were born any more competent. But make no mistake. We continue to be amazed at babies' competence. They take in cues from their environment remarkably early, learning and laying down memories."
Baby's Remarkable Abilities
Born with a Can-Do Attitude
Even though your baby can't care for herself, what she is capable of at birth may surprise you. She's born with 70 innate reflexes designed to help her thrive, some of which are truly remarkable. "Reflexes like the tonic neck reflex -- in which your baby turns his head to one side, straightens one arm, and holds the other out -- are critical to labor and delivery, helping your baby squirm around during the birth process, stimulating the uterus to keep contracting," says Dr. Brazelton. In essence, he's helping your labor progress.
Other reflexes are less subtle to a new parent. If left on his mother's abdomen in a dim, quiet room after birth, a healthy newborn "will rest for about 30 minutes and will gaze at his mother's face on and off," reports Marshall Klaus, MD, who wrote the first textbook on neonatology and has coauthored a number of popular books for new parents, including Your Amazing Newborn (Perseus). Then he'll begin smacking his lips and moving toward the breast completely unaided, using a powerful stepping reflex and bobbing his head up and down to gather momentum. Once at the breast, a newborn will open his mouth wide and place his lips on the areola, latching on all by himself for his first feeding. From that point on, these inborn responses will affect your newborn's every move. The rooting reflex, for example, helps your baby seek nourishment. However, seemingly random, reflexive movements may be more intentional than we first thought. "When in a quiet, alert state, and in communication with a caregiver, some babies will reach out to try and touch something," says Dr. Klaus.
Normal newborns at birth apparently have the underlying potential to reach for things, he explains, but their strong neck muscles are linked to their arms, so that a slight neck movement moves the arms as well. This connection protects the baby's head from suddenly dropping forward or backward.
Can Babies Think?
It depends upon how you define thought; of course, a newborn can't share ideas. But some researchers believe that babies do put concepts together (albeit on a primitive level), evidenced by the fact that they remember and recognize their mother's voice from birth, and express and respond to emotions before and immediately after birth. One could argue that memory and emotion are inextricably linked to thought. "A baby's brain grows very differently depending on what sorts of experiences the baby has both in utero and after birth," says Wendy Anne McCarty, PhD, the founding chair and faculty of the Prenatal and Perinatal Psychology Program at the Santa Barbara Graduate Institute, in California. "During gestation, birth, and early infant stages, we learn intensely and are exquisitely sensitive to our environment and relationships. From the beginning of life, we're building memories." Other experts say that a baby's brain is too undeveloped to do more than orchestrate vital body functions. One fact remains clear: Newborns learn every day and apply that knowledge to their growing repertoire of skills. So can a newborn really think? Watch your baby, and judge for yourself!
Development in Reverse?
Dr. Klaus discovered that newborns instinctively reach out until about 3 weeks of age, when this ability apparently disappears until about 3 months of age. This coincides with the time it takes your baby to start learning how to integrate his senses and gain control over his muscles. This is a prime example of how your baby's need to learn so much, so quickly, means he must set aside some tasks while focusing on other, more important ones, such as regulating his sleep-wake cycles and figuring out how to focus his brand-new eyes on all the new sights around him.
So why do all these useful survival instincts seem to disappear so early -- some as early as the 2-month mark? A baby spends the first few months of his life reacting to the world around him. But once he starts to understand where he ends and the world begins, which is partly a matter of brainpower, and partly a matter of practice, some behaviors that were once reflexive become active, as gradually baby learns that he can make things happen on his own and affect his environment. And, says Dr. Brazelton, "Just watching a baby learn is enough to give you hope for the human race."
Fun Facts About Your Baby's Senses
What Baby's Doing
Month 1: Recognizes his parents' voices and mimics facial expressions
Month 2: Knows enough about cause and effect to realize that crying gets results and smiles back
Month 3: Maintains regular eye contact and cries differently to express distinct needs
Senses and Sensibility
Touch: Your newborn's skin is his largest and most highly developed sensory organ. At birth, your baby can respond to variations in temperature, texture, pressure, and pain. Your newborn's lips and hands have the largest number of touch receptors, which may account for why newborns enjoy sucking on their fingers.
Smell: By the 28th week of pregnancy, your baby can use her nose. One piece of evidence: Newborns placed between a breast pad from their mother and one from another woman most often turn toward the one with the alluring Mom-smell.
Taste: In your womb, your baby gets a sampling of flavors as he swallows amniotic fluid. Studies have shown that fetal swallowing increases with sweet tastes and decreases with bitter or sour tastes.
Hearing: Although your baby's middle ear is still somewhat immature at birth, as are the sound processing centers of his brain, your newborn can hear you and will prefer human speech over any other sounds, especially if the voice is yours.
Vision: By the time you actually meet your baby, her eyes are capable of excellent vision; however, her brain is still too immature to distinguish between different shades of color. By the time your baby is 3 months old, she will want to look at the world around her. She'll prefer bright colors or sharp contrasts, and her favorite thing to look at will be faces.
Holly Robinson lives with her husband and their five children outside Boston.
Originally published in American Baby magazine, October 2005.
All content here, including advice from doctors and other health professionals, should be considered as opinion only. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.