prolog
How to calculate your baby's age

Chapter 0.
Pregnancy~Birth Baby Development

“A baby’s brain development begins in early pregnancy.”
Baby's brain development during pregnancy
Nutritional status of pregnant women / The impact of stress during pregnancy on the baby's brain development / The importance of exercise during pregnancy / Misconceptions about prenatal care / Misconceptions about breastfeeding

Chapter 1.
Baby Development from Birth to 3 Months

“Babies can see and hear from the moment they are born!”
Baby's visual development
Even newborns can see blurry / Gently shake your face in front of your baby / They can also understand their parents' emotions
*** TIP Early detection of congenital cataracts
+++Visual response test: Moving the eyes sideways

Baby's hearing development
Even newborns can hear / You need to find out quickly if your baby is deaf / If your baby is born deaf, their motor development will be delayed
+++Auditory response test: Turning the head to the sound of a rattle
*** TIP Early detection and treatment of congenital hearing loss

Development of baby's large muscles
You need to understand the 'physiological bending state'/There is no need to intentionally stretch out the baby's legs/Use a carrier during waking hours/When the baby is asleep, you should put the baby to sleep on his/her back on the floor/Reduce random movement/Check if the baby's neck is tilted to one side/Check the length of the baby's legs
*** TIP How to Massage Your Baby's Neck
*** TIP How to check leg length at home
+++Large muscle development test: Head lifting from prone position

Development of baby's small muscles
A newborn's hand is clasped with the thumb in the palm / A rattle should be about the thickness of a pencil / A pacifier helps lip movement and reduces stress / A home environment that activates the brain's neural network

Baby's emotional regulation skills
Soothe a crying baby with small stimuli first.
*** TIP: Soothing a Crying Newborn Step by Step

Q&A Birth to 3 months
Baby Column 1 Should my 1-month-old baby have a developmental checkup?
Baby Column 2 Is it dangerous to raise a baby face down?

Chapter 2.
Baby development at 4-6 months of age

“A baby’s brain development requires a variety of stimulation!”

Baby's body measurements
Measure head circumference regularly/Be aware of weight loss in breastfed babies/Test breastfed babies for iron deficiency anemia
+++Body Measurements: Measuring Baby's Head Circumference
+++Body Measurements: Weighing Your Baby

Baby's visual development
Mom's face is clearly visible / Don't play with eye contact too much / Can distinguish different shapes / Shows interest in face in mirror / Baby starts to feel shy / Needs a neighbor
*** TIP: Becoming friends with a shy baby
+++Visual Response Test: Eye Following

Baby's hearing development
Turn your head toward the sound/Please expose your child to a variety of sounds/Please refrain from arguing with family members.
+++Auditory response test: Turn your head toward the sound

Baby's skin sensory development
Please be physically intimate often.
Vestibular stimulation in babies
Vestibular stimulation provides a sense of security to babies.
Development of baby's large muscles
You can lift your upper body up to your chest (Elbow Support) / Do not try to stand the baby up / If possible, do not sit the baby down / Always put the baby on his/her stomach during waking hours
+++Large muscle development: Supporting the upper body with the elbows Elbow Support
+++Large Muscle Development: Head Control
+++Large muscle development: Support with palms and raise the upper body Hands Support
+++Large muscle development: Grasping one's own feet with one's own hands

Development of baby's small muscles
I can reach out and grab a toy / I can grab a bean / When my back muscles get stronger, I can't reach forward / I can eat with a spoon / Don't force me to eat with a spoon
+++Fine muscle development: reaching out and grabbing a toy
+++Small muscle development: Grabbing beans with the palm of the hand

Baby's language development
Don't worry if your baby can't babble/Don't be surprised if they scream/They may even say 'mamma'/Talk to your baby through facial expressions and voice tones/They can recognize you just by hearing your voice/Express your feelings accurately about your baby's behavior/Let them hear different people's voices
+++Interaction: Make eye contact

Baby's emotional regulation skills
Babies cry even when they are bored
+++Emotional Control: Finding the Cause of Crying

Q&A 4-6 months old
Baby Column 1 Only use the walker for 20 minutes at a time!
Baby Column 2 Caring for a Baby with a Difficult Temperament

Chapter 3.
Baby development from 7 to 10 months old

“I can sit up and crawl on my own!”

Baby's visual cognitive development
They learn that people and toys don't disappear/ They can perceive depth/ They can remember things that happened the day before/ They can tell a puppy from a cup, but have difficulty telling a puppy from a cat.
+++Visual Cognition: Finding the Toy in the Box
+++Visual Perception: Looking Down from the Sofa

Baby's auditory cognitive development
I can hear even the smallest sounds/I can distinguish sounds and words/My baby doesn't respond when I call his or her name
+++Auditory response: Recognizing the direction of small sounds

Development of baby's large muscles
Back crawling/quad crawling/back crawling/back crawling with buttocks up/standing up while holding onto the sofa without back crawling or all fours crawling/sitting up on your own/transitioning from sitting to crawling/standing up while holding onto the sofa
+++Large muscle development: Sitting upright

Development of baby's small muscles
Give them a chance to use their hands/The thumb should extend out from the palm/'Lid hand' is often hereditary/Very small babies may have difficulty with hand control/Give them a chance to move their hands and lips and tongue/Babies with open mouths have difficulty chewing hard foods

+++Fine muscle development: Holding a toy with both hands
+++Fine muscle development: Picking up small snacks with fingers

Baby's language development
Tell me the names of things/The time of first speech varies depending on the mobility around the mouth/The ability to understand speech is more important than speaking.
*** TIP Things to keep in mind when assessing language comprehension
+++Language Development: Remembering Object Names
+++Language Development: Understanding 'No'

Baby's interest in objects
Do you have a particular favorite toy or object?

Baby's intimacy with people
Just because your baby doesn't smile often doesn't mean they're not close enough/Give them time to observe strangers and relax/Check your baby's ability to regulate their emotions in stressful situations/Discipline your baby with silence and distance/When they're bored, they'll whine and throw tantrums
+++ Intimacy test for strangers
+++Test of emotional regulation in stressful situations

Q&A 7-10 months old

Chapter 4.
Baby Development at 11-16 Months

“I can walk by myself!”

Iron Deficiency Anemia Test in Babies
If your baby is not eating well, first test for iron deficiency anemia. In Israel, all babies are tested for iron deficiency anemia at 12 months of age.
*** TIP: Feeding a baby aged 11 to 16 months

Development of baby's large muscles
You should be able to walk sideways while holding onto the sofa.
*** TIP: Babies who are slow to walk on their own
+++Large muscle development: Walking while holding onto a sofa with one hand
+++Large muscle development: walking alone

Baby's visual cognitive development / fine motor development
Hand-eye coordination begins/Baby begins to move their lips and speak.
*** TIP Hand manipulation development by month
+++Fine muscle development: Picking up beans with thumb and index finger

Baby's language comprehension
Can understand words like sit, stand, love, bye bye, etc./The time to first speak varies greatly
+++Language development: Recognizing object names and action words

Baby's emotional regulation skills
Respect your baby's temperamental characteristics/Don't force a thinking baby to play/Send a squirrel-type baby to the playroom early
*** TIP What is the Infant and Toddler Development Screening Test?

Q&A 11-16 months
Baby Column 1 Do babies born in winter have slower development?
Baby Column 2: A baby who can't walk, a baby who won't walk
Baby Column 3 Strong sense of humor increases EQ.

Chapter 5.
Baby Development at 17-24 Months of Age

“As the quality of movement improves, the number of groups increases!”

qualitative mobility of the baby's large muscles
Start walking, climbing stairs, and running in place.
+++Large muscle qualitative mobility: Climbing stairs alone

qualitative mobility of small muscles in babies
If the quality of small muscle movement is poor, toilet training is delayed. / If the quality of small muscle movement is poor, speaking is also delayed. / The baby is receiving speech therapy to correct pronunciation on his own.
+++Small Muscle Qualitative Motility: Putting a Coin in a Piggy Bank

Baby's interaction/communication development
Above all, language comprehension is important. Babies speak through facial expressions and gestures.
+++Language Comprehension: Recognizing Possessive Cases
+++Language comprehension: Understanding 'the same'

Baby's emotional regulation skills
As they become more athletic and larger, their herds grow larger. Overprotection, abuse, and neglect all lead to the same outcome: immaturity in emotional regulation.
+++ Emotional Control: Identifying the Stages of Your Baby's Tantrums
*** TIP Some babies may not have language development delays that are easily apparent.

Q&A 17-24 months
Baby Column 1: Don't force children with poor motor skills to play sports!
Baby Column 2: Emotional Control Methods Based on Your Child's Temperament

Chapter 6.
Child development at 25-36 months of age

“Your body movements become more active and your language comprehension skills improve!”

qualitative mobility of the child's large muscles
A sense of balance is important
*** TIP Sensory-Motor Integration
+++ Sensory-motor integration: Seeing a line and jumping long distance
+++ Sensory-motor integration skills: Following the 'Twinkle, Twinkle, Little Star' rhythm

qualitative mobility of small muscles in a child
I can string beads/I can hold a pencil and write a line/I'm starting to control my bowels
+++ Small muscle qualitative motility: drawing a circle

Child's language development
I can understand big, small, many, few/Please wait even if the time is late
+++ Language comprehension: Understanding 'more' and 'less'

Building intimacy in children
Even with people you disliked for no reason, you can build intimacy by accumulating positive experiences. / Experiences at daycare centers and with peer groups are essential for social development.

Developmental disorders that should be detected early at 25 to 36 months of age
Reactive Attachment Disorder/Autism Spectrum Disorder/Receptive-Expressive Complex Language Disorder
*** TIP How do I conduct a professional development assessment?

Q&A 25-36 months

Chapter 7.
Child development from 37 to 60 months of age

“They adapt well to daycare and kindergarten!”

Child's motor development
A variety of physical activities are needed. One-on-one physical play is recommended for children with poor quality motor skills and sensory-motor integration.

Child's language development
Even when sleeping, you can understand what your parents say in everyday life. / There are still significant individual differences in your child's speech. / There is no need to start speech therapy early just because your child is late in speaking. / Understand your child's pronunciation level. / Even if your child's speech development is excellent, they need various play activities in a peer group.
*** TIP: Communication techniques to improve your language skills
*** TIP A test tool that can evaluate the cognitive ability of children over the age of 3.

Q&A 37-60 months

Appendix 1 - What to do when development is not within the normal range
Appendix 2 - Early Stimulation Methods to Promote Development in Premature Infants
Appendix 3 - Example of Writing a Daycare Center Activity Report

***Special supplement
Baby Development Tests at Home 55 & Baby Development Activities 117

Baby growth and development tests are a measure of the baby's brain development.

A baby's growth and development test is not only a simple test that measures the level of physical growth and development appropriate to the developmental period, but is also an important test that confirms the level of brain development of the baby at each developmental stage.
As babies grow, it may seem like a natural progression for them to learn to hold up their heads, crawl, walk, respond to sounds, talk, pick up beans with their thumbs and index fingers, and play with their peers, but all of this is possible only when their brain networks are well-developed for their age.
This is because when a baby's brain development is not sufficient, it is difficult for the child to achieve motor, language, and cognitive development appropriate to the level of that developmental stage.


This book provides developmental characteristics and parenting guides for each developmental stage of a baby, as well as motor development, language development, and behavioral development tests and developmental play methods that can be easily done at home.
The 'Baby Development Test at Home', organized by developmental stage, consists of tests that can detect any delays in your baby's growth and development at an early stage.
Even if you don't read the entire contents of this book, I recommend that you conduct a 'Baby Development Test at Home' during the appropriate period to quickly detect any developmental delays in your baby and receive professional treatment.

Parenting methods also vary depending on the baby's developmental characteristics.

For new parents with no parenting experience, everything about the baby is a source of worry.
Unlike in the past when families raised their children together, these days it is difficult to receive help from those around them, so parents are anxious about everything, such as when their baby's neck will be raised, whether their head circumference is too big, when they will learn to crawl and walk, and when they will start talking.
The abundance of parenting information online can actually cause parents to lose their way and wander.
Not all babies grow at the same rate and with the same developmental characteristics.
Each baby has a different temperament and inherits different genes.
Therefore, parenting methods and play methods should change depending on the developmental characteristics of my baby.
Efforts that do not match the baby's developmental characteristics can actually cause stress to the baby.
Being a little faster or slower than others doesn't mean much.
That's why it's important to understand your baby's developmental characteristics and have basic knowledge about the entire baby development process.
Based on this basic knowledge, you can reduce parenting anxiety and stress by drawing up a parenting roadmap that suits your baby.

Detailed information and explanations to help you map out your baby's parenting roadmap.

This book consists of two volumes: the main text and a special appendix.
This book provides detailed explanations of the developmental characteristics of babies at each developmental stage, from the fetal stage during pregnancy to 60 months after birth, using various pictures and videos that utilize QR codes.

After the baby is born, you will be so focused on raising the baby that you will not even notice how time flies.
This book is organized by developmental stage and topic, so you can easily find the part you need and get help.


If you are pregnant and still have some time and mental space, I recommend reading this book from the beginning with your family members who will be raising the baby.
Before your baby is born, having a thorough understanding of your baby's growth and development from birth to 60 months will be of great help in understanding your baby's behavior and determining how to raise him or her.


A special supplement that can be used immediately even during busy parenting times.
Baby Development Tests at Home 55 & Baby Development Activities 117

The special appendix, organized as a separate volume, is designed to be used immediately after the baby is born and when the full-fledged parenting begins, making you feel very busy.
It is composed of 55 different developmental test methods for each developmental stage and 117 developmental games to play with parents.
We provide detailed illustrations explaining the test and play methods so that new parents who do not have a parenting expert to ask questions or give advice in various parenting situations can easily use them.
In addition, we have tried to help new parents understand by providing short videos using QR codes for parts that may not be explained well with illustrations.

Discover your baby's developmental characteristics early
Maximize your innate potential!

The goal of parenting should be to provide opportunities for babies to develop their innate potential to the fullest extent possible.
This book contains the 30 years of expertise of Dr. Kim Soo-yeon, a baby development expert, to help new parents who have made the bold decision to have and raise a baby in an era with the lowest birth rate raise their baby more easily.
"Kim Soo-yeon's Baby Development Encyclopedia" will help you check whether your baby is growing and developing well at home and maximize your precious baby's potential through various developmental play and baby care methods that your baby needs.