Milestones: what typical development looks like in the early years

Transcript

RyanA grandfather is babysitting his nine-month-old granddaughter. She drops her spoon off the high chair, and then she leans over and looks down for it. He laughs. And then he opens a little app on his phone and taps a box.

SoheeBecause looking for an object that's dropped out of sight is one of the milestones for nine months from the Centers for Disease Control and Prevention, the CDC. He's doing something with a name. It's called developmental monitoring.

RyanWelcome to EPPP Prep, the podcast. I'm Ryan.

SoheeI'm Sohee. Today we're walking through normal development in the first years of life: the reflexes, the motor sequence, the growing brain, language, and how milestones are actually used.

RyanLet's start at birth. All healthy babies are born with newborn reflexes. The psychology textbook calls them inborn automatic responses to particular forms of stimulation.

SoheeAnd they help the newborn survive until more complex behavior is possible. They're present in babies whose brains are developing normally, and they usually disappear around four to five months.

RyanThe rooting reflex: stroke a baby's cheek, and the baby turns the head that way and begins to suck. The sucking reflex is the automatic sucking motion itself. The grasping reflex: put a finger in the palm, and the baby grabs it.

SoheeAnd the Moro reflex is the response to the sensation of falling. The baby spreads the arms, pulls them back in, and usually cries.

RyanNewborns also come ready to connect. Vision is their least developed sense, yet they already prefer faces. In one study, three-week-old babies sucked harder on a pacifier when it played their mother's voice.

SoheeNow motor development. Lifespan Development describes two patterns. Cephalocaudal means growth starts at the head and moves downward. Proximodistal means development begins at the center of the body and moves outward.

RyanSo, cephalocaudal: babies first hold their heads up, then sit, pull up, and finally walk. Proximodistal: they grab an object with their whole hand before they can manipulate it with individual fingers.

SoheeAnd that's the difference between gross and fine motor skills. Gross motor skills use large muscle groups, for balancing, running, jumping. Fine motor skills coordinate small actions, using the muscles in the fingers, toes, and eyes, like grasping a toy or using a spoon.

RyanWhat about timing? The psychology textbook says that on average babies sit alone at seven months, and ninety percent reach that milestone between five and nine months.

SoheeSame idea for walking. Lifespan Development puts the average at twelve months, but says infants can begin as early as eight months or as late as seventeen to eighteen months. There's a range.

RyanSo when is a delay a concern? The psychology textbook gives a clear rule of thumb. If a child is showing delays on several milestones, that's reason for concern, and the caregiver should talk with the pediatrician.

SoheeLet's go inside the head. After neurons form, they connect to each other. That's synaptogenesis. Lifespan Development says by age two, children have about fifteen thousand synapses per neuron.

RyanAnd then the brain gets selective. Connections that are used often grow stronger. The ones that aren't die off, in a process called synaptic pruning.

SoheeBecause synapses are overproduced in the first two years, toddlers may have twice as many synapses in the cerebral cortex as adults. So pruning continues into the teen years.

RyanThe psychology textbook calls that early surge blooming, followed by pruning, which is thought to help the brain work more efficiently. And the brain grows fast. A two-year-old's brain is fifty-five percent of adult size. By six, it's about ninety percent.

SoheeNow my favorite part. Language. Babies begin to coo almost immediately. Then they babble, repeating syllables like ma-ma or ba-ba. Around twelve months comes the first meaningful word, and around eighteen months, they start combining words.

RyanAnd early words carry a lot of weight. When a baby uses one word to convey a whole thought, that's a holophrase. Ball might mean, where's the ball, or give me the ball.

SoheeThen there are two classic errors, and they're exam favorites. Overextension is using a word too broadly. A child calls a tiger a kitty. Underextension is using it too narrowly. The child calls her own cat kitty, but no other cats.

RyanBy eighteen to twenty-four months, children combine words into short sentences that skip grammar. More cookie. Go papa house. That's telegraphic speech, named for the old telegraph messages.

SoheeAnd by about two years, the psychology textbook says a toddler uses between fifty and two hundred words.

RyanPause and think. A two-year-old points at every man in the grocery store and says daddy. What's that?

SoheeOverextension. The word daddy is stretched to cover far more than it should. If she used daddy only for her own father and refused it for a picture of him, that would be the reverse, underextension.

RyanSo how do children learn language so fast? Two classic answers. B. F. Skinner said we learn language through reinforcement, like approval or being understood.

SoheeAnd Noam Chomsky criticized that, proposing that we're born with an innate capacity for language, which he called the language acquisition device.

RyanAnd the textbook's verdict is diplomatic. Both are right. Researchers now believe language acquisition is partly inborn and partly learned through interaction with our linguistic environment.

SoheeOkay, back to our grandfather and his app. CDC's Learn the Signs, Act Early program defines milestones as things most children, seventy-five percent or more, can do by a certain age.

RyanAnd here's why they chose seventy-five percent. CDC says it's meant to avoid a wait and see approach. Any missed milestone or concern should prompt discussion or action.

SoheeA few examples from the checklists. By nine months, looks for objects when dropped out of sight, and sits without support. By one year, pulls up to stand, walks holding on to furniture, and looks for things he sees you hide, like a toy under a blanket.

RyanBy two years, says at least two words together, like more milk, kicks a ball, and runs.

SoheeNow the distinction the exam cares about: monitoring versus screening. Developmental monitoring is observing how a child grows and changes over time. Parents, grandparents, and caregivers can all do it, with a brief checklist.

RyanDevelopmental screening is more formal. It uses research-based questionnaires or checklists, given by professionals trained in those tools. CDC says the checklists for monitoring are not a substitute for standardized, validated screening tools.

SoheeAnd timing. The American Academy of Pediatrics recommends general developmental screening at nine, eighteen, and thirty months, and autism screening at eighteen and twenty-four months, or whenever a parent or provider has a concern.

RyanPause and think. A nurse at a well-child visit gives a parent a formal, validated questionnaire at eighteen months. Meanwhile, the grandfather keeps his app checklist going every week. Which is which?

SoheeThe nurse's validated tool at a set age is screening. The grandfather's ongoing checklist is monitoring. Who does it, with what tool, and why.

RyanAnd what happens with a concern? CDC says don't wait. If a child isn't meeting one or more milestones, has lost skills they once had, or there are other concerns, talk with the child's doctor and ask about screening.

SoheeNotice that phrase, lost skills. That echoes what we said last episode about regression being a sign something may be wrong.

RyanThen families can request a free evaluation. For children under three, through the state's early intervention system. For three and older, through the local public school, even if the child doesn't attend there. And they don't need a doctor's referral to make that call.

SoheeSo on the exam, if a parent is worried and an answer choice says, let's wait and see how things look in six months, that's the tempting wrong answer. The CDC guidance is to act early.

RyanRecap time. Newborn reflexes, rooting, sucking, grasping, Moro, are inborn and usually fade around four to five months.

SoheeMotor growth is cephalocaudal, head down, and proximodistal, center out. Milestones have averages and ranges, and delays on several milestones are a reason to talk with the pediatrician.

RyanThe brain overproduces synapses, then prunes the unused ones. Language runs from cooing to babbling to first words around twelve months, then two-word combinations and telegraphic speech.

SoheeOverextension is too broad, underextension too narrow. Monitoring is ongoing and informal. Screening uses validated tools at nine, eighteen, and thirty months. And the rule is act early.

RyanIf milestones and ages feel like a lot of numbers, be gentle with yourself. You don't need every age. You need the sequence and the big distinctions, and you just reviewed them all.

SoheeTry a couple of practice questions on development while it's fresh. You're building this one block at a time. Thanks for listening to EPPP Prep.

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