Child Development and Milestones: Your 3-Year-and-9-Month-Old

Child Development and Milestones: Your 3-Year-and-9-Month-Old

They grow up so fast! Your child is feeling confident and capable — what should you do to let him reach his full potential?

Now that your little one is all of three years and nine months old, he's more capable than ever and he knows it! 45-month-old development is all about your child being more independent and social. Finding the perfect balance between giving your child enough room to grow while staying watchful will be a challenge, but keep at it and you'll find what works for you eventually.

3-Year-and-9-Month-Old Development and Milestones: Is Your Child on Track?

45 month old development and milestonesPhysical Development

45 month old development and milestones

Your child's gross motor skills are getting more advanced by the day. He'll be able to run around more confidently, and can hop and balance on one foot for up to two seconds. He'll also be able to catch a bounced ball most of the time.

His fine motor skills are also more sophisticated. Your 3-year-and-9-month-old child might be able to even pour, cut, and mash his own food. Your child can now dress himself, but don't be surprised to find his shirt inside-out or buttoned up the wrong way. These little mistakes are totally normal. He might still struggle with snaps or buttons, so give your independent little one clothes he can easily slip on.

At this age, your child is growing fast. Girls should weigh around 15.4 kg (33.9 lbs) and measure around 99.3 cm (39.1 inches), while boys should weigh around 15.8 kg (34.9 lbs) and measure around 100.8 cm (39.7 inches).


  • At this age, your child will be able to ride a tricycle or two-wheeler with training wheels! Just remember to equip your child with a helmet and knee and elbow pads to keep playtime safe and fun.
  • Now that your child's fine motor skills are more advanced, she will enjoy drawing and colouring even more. Get your child a box of crayons and have a stash of scrap paper ready for her to while away the hours drawing simple shapes like circles and squares. Expect a few drawings of your family as well.
  • She can also groom herself already, and can wash her hands and brush her teeth. You will probably have to keep reminding her to do these little things, so make sure that you communicate the importance of hygiene to your child.

When to Talk to Your Doctor

It's important to remember that children develop at different rates. If you don't observe the milestones above just yet, don't fret. However, if your child can't jump on one spot, and has trouble scribbling, talk to your doctor. 

Cognitive Development

Your 3-year-and-9-month-old child has never felt as capable as he does now, and so will start to want to do things himself — or at least try.  He'll start enjoying simple puzzles and will understand concepts like numbers (four candles on his birthday cake means he's four years old!). He'll also be able to name colours better. 

This is also the age when he'll start to grasp concepts like time (e.g. yesterday, today, tomorrow), as well as the idea of "same" and "different". He'll have a lot of questions about almost everything, which can get annoying, but be patient and encourage his curiosity.

Your child will also be more imaginative than ever, but will still struggle with differentiating between fantasy and reality. This can make pretend games extra fun, but can also spell trouble at bedtime if he starts imagining monsters under his bed, so be mindful about the kind of stories that he is exposed to.


  • This is the age when your child starts to reason and figure things out by himself, so feel free to take a few steps back and let him try to understand how to do things alone before stepping in to help.
  • Encourage his learning skills with sorting and counting games, as well as flash cards. You can also use simple board and card games.
  • Pick up on what sparks your child's interest and support it. Your child will probably enjoy celebrating holidays, so let her help out with the decorations. She might enjoy storybooks with rhymes and playing certain games. This is when her personality really starts to shine through.

When to Talk to Your Doctor

Again, each child is different, so don't feel bad if your child can't do everything listed above. But consult your paediatrician if your child shows no interest in interactive games or make-believe. If he can't retell a favourite story or loses skills he once had, speak to your doctor.

Social and Emotional Development

45 month old development and milestones

Even though your 3-year-and-9-month-old child will want to be more independent during this time, you should still continue to spend time with him every day. Your child will continue mimicking your behaviour, so make sure that you set a good example!

Your child will enjoy doing new things, and will enjoy playing with other children more. Because your child will probably have more exposure to other kids, he has learned how to take turns — though he may struggle with this at times.

He might have a best friend that he particularly enjoys playing with. Your 3-year-and-9-month-old little one will be better at understanding rules. You'll also notice that he has more control over his emotions, expressing anger with words rather lashing out physically (expect the occasional lapse, though). 

You child will also understand the idea of "mine" and "his/hers", and will be better at sharing. He is also capable of sharing a wider range of emotions, such as sadness, anger, happiness, and boredom.


  • As your child imitates you more and more, make sure that you communicate the dangers of activities like using a knife or lighting matches – he still has limited understanding of the concept of danger.
  • Continue to nurture your child's love of reading by getting him age-appropriate books. You could even enroll him in a library. 

When to Talk to Your Doctor

This is when your child will be highly social, so if she ignores other children or doesn't respond to non-family members, talk to your doctor. 

Speech and Language Development

Your child's language skills are getting more and more sophisticated, with 250 to 500 words in his vocabulary. Now, he should also be able to say his name and age, and can speak in complete sentences. He might even be able to tell stories!

He knows the basic rules of grammar by this point, like using "he" and "she" correctly. He'll be able to sing songs or nursery rhymes from memory, and can answer simple questions. 


  • You can encourage his language skills by having conversations with him and reading together.

When to Talk to Your Doctor

Some toddlers are more talkative than others, but if your child can't follow three-part commands, speaks unclearly, or can't retell a favourite story, talk to your doctor.

Health and Nutrition

You can ensure that your child reaches his full potential — physically and cognitively — by ensuring that he gets the right nutrition, sufficient sleep, and regular physical activity.

Depending on your child's level of activity, his/her daily nutritional needs are about:

  • Boys: 1,554 Kcal/day
  • Girls: 1,456 Kcal/day 

Your child's daily food intake should ideally consist of:

  • Carbohydrates

Your little ball of energy needs lots of carbohydrates to make sure that he/she has enough fuel for the day. Grains are the primary source of carbohydrates. Your child needs 4-5 ounces of grains a day, preferably from whole-grain sources as these are high in nutrients and fibre. 1 ounce of grains equals 1 slice of bread, 1 cup of ready-to-eat cereal, or ½ cup of cooked rice, cooked pasta, or cooked cereal.

  • Protein

Your child is growing a lot a this stage, so he/she needs protein to build muscles and repair tissue. Meat such as beef, poultry and fish, as well plant-based protein such as beans, tofu, quinoa, peanuts and lentils, are great sources of protein for the growing child. At this age he/she needs 3-4 ounces daily. 1 ounce equals 1 ounce of meat, poultry or fish, ¼ cup cooked dry beans, or 1 egg.

  • Fruits and Vegetables

Make it a goal to serve your child colourful food to make giving him/her fruits and vegetables a regular part of your food preparation. Purple grapes, orange squash and carrots, dark green leafy veggies, red strawberries, green broccoli, white cauliflower served throughout the week will ensure that your child gets enough fruits and vegetables in their diet. These are the primary sources of vitamins and minerals for your growing child, and at this age, he/she needs 1-1½ cups of fruits and 1½ cups of vegetables every day.

  • Dairy

Milk remains an important source of nutrition for your little one. Your little one needs at least 2 cups of milk per day. This could also be 2 cups of yogurt, 3 ounces of natural cheese, or 4 ounces of processed cheese.

Water should be your child's primary source of hydration — not sweetened drinks like fruit juice. You can make water more appealing by adding cucumber or fruit slices.

Your little one might be picky with his food at this age, but do what you can to introduce new food to encourage a balanced diet. Sometimes it's all about packaging — try making eating fun with cookie cutters to slice fruit and sandwiches, or come up with interesting names to make them sound more appetising.

Vaccinations and Common Illnesses 

Ideally, your little one should have all of his/her vaccinations complete by this age. To find out what vaccinations your child should have got up to now, and check if this schedule is up-to-date, click here. 

As a reminder, your child should already have the following vaccinations:

  • MMR
  • Flu
  • Hepatitis A
  • Hepatitis B

If your child is missing any of these vaccinations, don't hesitate to consult your doctor.

When to Talk to Your Doctor

You should be visiting your doctor at least once a year for checkups. If your child isn't enrolled in a preschool, be sure that he has the necessary vaccinations before he enters school.

There are no vaccinations due this month, unless your paediatrician advises otherwise. 

If you notice that your child is shorter than other children his age, remember that your child's growth is highly dependent on genetics. However, you can also ask your doctor to find out if this is just normal. You should also consult your doctor if you observe any unusual behaviour or drops in her weight.

Each child is unique and wonderful in their own way, so don't fret if your child is not developing at the rate that other children are. Focus on keeping your little one healthy, happy, and well-adjusted, and seek the guidance of your family physician to make sure that your child reaches her full potential.

Lead image courtesy: Dreamstime

Source: WebMD, Centers for Disease Control and Prevention, Lancaster General Health

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