Baby - Baby Development Stage

Newborn

Similac - Baby's development: Month 1

My newborn baby: a whole new world

Congratulations, and welcome to motherhood. You might feel elated and anxious or be experiencing any range of emotions, but one thing is certain: You have a year of incredible firsts ahead for both you and your newborn. Here is some useful information as you begin your first month of motherhood:

Newborn baby sleep patterns and tips

- Your baby will likely sleep for two to three hours at a time, 16 to 18 hours a day.
- Try to feed your ba...

Month 2

Similac - Baby's development: Month 2

Your baby is growing more attached to her world

My 2-month-old baby: a more familiar world

Babies use many of their senses to get to know their mothers while they are still in the womb. As your baby takes in everything in the "outside" world, she uses that information to communicate with you.

2-month-old baby sleep patterns and tips

- Your baby probably will sleep for shorter periods during the day and longer stretches at night.
- To help her get used to falling back to sleep on her own, gently place her down in the crib whil...

NutriciaProgram - Baby Week 8

Your baby will discover the use of hands around this time – their instinctive grasp reflex lessens so as to explore different objects using a wider range of movement. Undoubtedly, your baby will be fascinated by anything new, so encourage him or her with baby-safe objects that can be easily gripped.

NutriciaProgram - Baby Week 9

In this month, your baby may begin to experiment with certain sounds, which are more familiar to you, such as the letters P, B and M, which can easily be made with the lips. No surprises then that 'mama' and 'papa' are often the first words spoken by babies!

NutriciaProgram - Baby Week 10

By now, your baby's body will have completely uncurled, leaving his or her spine long and straight. Your baby should be able to hold his or her head up in line with the body and may soon be using arms for support. Your baby's hands, however,are still a constant source of fascination – keep an eye on them, as your baby may try to reach for objects, though he or she may not be able to exert much control over them yet.

NutriciaProgram - Baby Week 11

Although loud noises may startle your three-month old baby, the sound of your voice should quickly soothe them. Babies' curiosity is limitless; they take a keen interest in what's going on around them and use as many senses as they can to explore their world. Touch is the only sense that gives your baby the three things he or she needs: a sense of safety and security, involvement with the world and a channel through which you can communicate with your baby and he or she can respond to you.

Month 3

NutriciaProgram - Baby Week 12

At this point, it's very important to keep stimulating your baby's mind and body. A moving or musical mobile above your baby's cot, placed at a level that's just beyond reach will help to strengthen your baby's muscles as he or she reaches up for it. It will also stimulate his or her mind as your baby registers what's above and the effect he or she can have on it. Bright colors, rattles and chimes will entertain your baby well enough and are excellent for encouraging hand-eye co-ordination. Your baby may also be showing signs of having a sense of humor and more powerful kicks – so beware!

Similac - Baby's development: Month 3

Your baby begins showing his personality

My 3-month-old baby: full of discoveries

By month three, your newborn will probably begin developing a personality all his own. He also might be reaching for objects, smiling spontaneously, and turning in the direction of your voice. Now might be a good time to familiarize him with new toys, textures, and people.

3-month-old baby sleep patterns and tips

- Your baby might be sleeping for five- to six-hour stretches during the night, but not all night.
- A regular bedtime...

NutriciaProgram - Baby Week 13

You may notice that your baby is much more attentive and able to express his or her feelings and personality. Grabbing things comes more easily, and he or she has a tendency to express excitement through gurgling and much waving of arms.

NutriciaProgram - Baby Week 14

Your baby is on the verge of a new set of developments. As the arms, upper body and neck become stronger, your baby will be able to sit up, wriggle and roll around. If nappy-changing has become trickier, move the changing mat down onto the floor to avoid accidents and never leave your baby alone for any length of time.

NutriciaProgram - Baby Week 15

A lot can happen from four to six months. Your baby may have learnt to roll over (from front to back, not the other way around just yet!), sit up, try solids for the first time and even form his or her first words. Continue to encourage and reassure your baby by smiling, or giving a round of applause! Your baby's development will become even more dramatic, which means that soon, some of your baby's much-needed nutrients will come from solid foods, though milk remains his or her core diet for now and up to 12 months.

Month 4

NutriciaProgram - Baby Week 16

At four to six months, you may be amazed at the range of new sounds that your baby can make. Along with coos and babbles, you may even be able to hear 'ma' and 'pa'. Don't get too excited, though! Your baby is still learning how to make words and it will be a while before your baby knows to call you 'mama' by name. Nonetheless, it will be entertaining to listen to.

Similac - Baby's development: Month 4

Your baby might join the conversation

My 4-month-old baby: a sound foundation

In month four, your baby's personality has probably grown even more pronounced. By the end of the month, she might be laughing out loud and attempting to carry a conversation. Try imitating her laugh and communicating with her. This is also the time to start learning how you can help protect her from diseases.

4-month-old baby sleep patterns and tips

- Your baby might be sleeping about 12 to 15 hours total every day, including naps.
...

NutriciaProgram - Baby Week 17

At 17 weeks, your baby needs approximately 14 to 16 hours of sleep a day, with three naps during the day. Moreover, your baby should be able to sleep though the night without the need for a nighttime feed. You can encourage your baby to drop a night-time feed by feeding him or her more during the day. You should be able to snatch quick moments of rest during the day, for your baby would have learnt to entertain himself or herself by now – albeit, by experimenting to see the results of his or her actions. Do not fret, as long as your baby is within the cot, he or she should be safe!

NutriciaProgram - Baby Week 18

During your baby's fourth month, you might start to hear genuine laughs or giggles, especially during playtime. Tickling is the most obvious way to encourage laughter, but you should laugh along with your baby (which shouldn't be too difficult!) as this will give him or her positive encouragement. Remember not to startle your baby too suddenly, though, while trying to make him or her laugh – this might have the opposite effect instead.

NutriciaProgram - Baby Week 19

Studies have shown that chatting and singing to your baby can aid speech development. Although he or she might not be able to understand you, your baby will process the sounds and eventually copy what has been heard. Simple, daily interaction, whether it's talking, laughing or smiling, will help your baby to develop. Another way to aid learning is to fill a plastic container with rice or pasta and let your baby hold it to practice using his or her hand and finger muscles. Make sure you implement a routine as well, this will help your baby to connect with you better and sleep more easily at nig...

Month 5

NutriciaProgram - Baby Week 20

Babies learn faster in the early years than at any other time of life and you can help encourage this development in a number of ways. Talking and singing to your baby helps with speech development, while teaching your baby actions or signs for certain words will help him or her to understand the meaning.

Similac - Baby's development: Month 5

Your baby grows more curious and cautious.

My 5-month-old baby: growing stronger, and wary of strangers

By the end of this month, your 5-month-old baby will probably be able to sit up with some support, and be able to pass toys from one hand to another. Depending on how long your friends and family visit you, your baby might start displaying a wariness of strangers.
5-month-old baby sleep patterns and tips

- Your baby could start waking up more during the night to feed, and might not yet sleep longer than five to six hours at a time....

NutriciaProgram - Baby Week 21

The floor is an ideal place to play. Place your baby on the tummy and encourage him or her to stretch for toys that are slightly out of reach. This will strengthen your baby's stomach muscles and provide the ideal opportunity to roll over, an important milestone in your baby's development. If your baby is ready to sit up without support, move him or her into a comfortable sitting position and once it appears that your baby is unlikely to fall over, place some pillows around him or her. Keep an eye on your baby while he or she is playing in an upright sitting position, just in case!

NutriciaProgram - Baby Week 22

Your baby's vision should have improved to the point that he or she is capable of tracking moving objects. Your baby may also be able to mimic certain actions, which should provide you with some entertainment for a change during playtime!

NutriciaProgram - Baby Week 23

Babies at this age will soon learn what happens to an object if they release it from their grasp or throw it. Practicing this newly acquired skill can be most enjoyable for them – although, understandably, perhaps not quite so much fun for you! This is also a time when some babies learn how to crawl, although not all babies will take to crawling – some will prefer to shuffle around on their bum and others progress straight from standing up and leaning to walking. Babies at 23 weeks old are generally able to perceive the world almost as well as adults, hence, it is important to maintain a conve...

Month 6

NutriciaProgram - Baby Week 24

As your baby's natural grasp reflex turns into more controlled hand and finger movements, he or she will be able to explore objects by grasping and shaking them with his or her hands, rather than simply sucking on them. Your baby may also experience his or her first tooth during this month, which will appear on the bottom gum, up front and centre!

Similac - Baby's development: Month 6

Your baby lays the groundwork for speech

My 6-month-old baby: new ways to play and teach

Your 6-month-old baby lays the groundwork for speech with every sound she makes. Keep talking with her this month. Also, your baby is becoming more aware of you as a separate person. A good way to help calm her fear of being alone is by playing "peekaboo."

6-month-old baby sleep patterns and tips

- Once your baby is 6 months old, she'll probably be sleeping through the night. But she occasionally might wake up during the night.

NutriciaProgram - Baby Week 25

Your baby can now see further and focus better, even as far as his or her toes. As the world becomes a more entertaining and colorful place, it's a good idea to keep your hair tied back or glasses out of reach. By the age of six months, your baby's eyesight would have improved even more and he or she will be able to see across the room.

NutriciaProgram - Baby Week 26

Your baby's growing interest in anything and everything will mean that in a short period of time, at seven to nine months, your days will be spent keeping him or her out of harm's way. As your baby's personality develops, he or she may become more assertive and display preferences for favorites, such as foods and toys, while shunning openly what he or she dislikes. Don't be worried if your little one isn't dropping milk feeds just yet. Milk is still an important part of your baby's diet as it provides essential nutrients to compliment your baby's weaning diet. And if your baby should begin sho...

Month 7

NutriciaProgram - Baby Month 7

At seven months, as your baby begins to understand the concept of space, it will dawn upon him or her that you are not joined at the hip. This creates a 'separation anxiety', which means that your baby will become scared and clingy whenever you try to leave the room, even if it's just for a moment. Some babies may get clingy when their parents put them down and move away by just a few feet. To ease your baby's separation anxiety, play hiding games, such as hiding his or her favorite toy and asking your baby to find it.

At this age, babies may also be eager to try and feed themse...

Similac - Baby's development: Month 7

Your baby’s first tooth grows, but you might not see it

My 7-month-old baby: your baby's growing world

Your 7-month-old baby will likely start moving more independently this month, and might begin exploring his surroundings in new ways. In addition, his first tooth could be arriving soon. You'll need to help your baby cope with teething while you continue to foster his development.

7-month-old baby sleep patterns and tips

- Separation anxiety your baby might have developed last month could keep him up at night.
...

Month 8

NutriciaProgram - Baby Month 8

When it comes to your baby's nutrition, no single food can give your baby all the nutrients they need. The only way to ensure that they get the right balance of vitamins and minerals, as well as the energy they need for exploring and growing, is to provide a varied diet. You may want to introduce new flavors and a slightly thicker, mashed consistency once your baby is past the first weaning stage. These new foods will help your baby to learn to eat and develop chewing skills. A thicker, chewier texture helps your baby's speech muscles to develop. If your baby refuses to eat lumpy foods at firs...

Similac - Baby's development: Month 8

Your baby is in the mood to move and explore

My 8-month-old baby: moving in big, new ways

Crawling and cruising are the hallmarks of this month as your 8-month-old baby experiments with all-new ways to explore the world around her. When your baby is standing, you can help by holding her favorite toy just out of reach and getting her to "cruise" along the furniture to get it.

8-month-old baby sleep patterns and tips

- If your baby has started teething, she might start waking up in the middle of the night uncomfortable...

Month 9

NutriciaProgram - Baby Month 9

The part of your baby's brain which controls motor skills (or movement skills) has already developed to help your baby control his or her upper body. However, during this next stage, it's the turn of the lower body, hands and feet to develop. As your baby's control over their leg muscles grow, he or she will be able to bear more weight on their feet and will probably enjoy bouncing up and down on your lap or in a bouncer. This is also a time when you should start baby-proofing your house. Some babies will learn to crawl, though not all babies will take to crawling – some will prefer to shuffle...

Similac - Baby's development: Month 9

Your baby is getting the hang of using his hands

My 9-month-old baby: learning to grab, bang, and throw

Your baby might be developing new skills including the ability to grab anything that is within reach. In addition, he might start shaking, banging, dropping, and throwing any item he can lift, so be careful. If your baby hasn't already, he might say "mama." However, some babies could go months longer before they start using new words. This is completely normal.

9-month-old baby sleep patterns and tips

- Baby separa...

Month 10

NutriciaProgram - Baby Month 10

The age of 10 to 11 months is a time for some very special milestones in your baby's development. First words will soon be heard and first steps taken as your baby's strength and co-ordination improves. Your baby will begin to understand that when they throw something, it travels across the room. It sounds simple, but they haven't always held the understanding that their actions have consequences. Keep conversing with your child as well. This is the time when your baby is starting to understand simple words and phrases and doing so will help them to improve their language skills. If your baby...

Similac - Baby's development: Month 10

Your baby is growing more comfortable with her expanding world

My 10-month-old baby: Handling baby's new emotions and abilities

Your 10-month-old baby might be interacting with people and showing off her new skills every chance she gets. She also might be feeling and expressing new emotions and abilities. Whether she is vocalizing or walking while holding on to furniture, you can help her deal with her expanding world this month by reciting nursery rhymes, singing songs, and taking her to new places for the first time.

10-month-...

Month 11

NutriciaProgram - Baby Month 11

Over the past few months, your baby has been strengthening their leg muscles in preparation for walking through crawling and kicking. They may begin pulling themselves up to a standing position all by themselves, or even take their first tentative steps while holding onto your hand, furniture or walls. Each baby develops in his or her own way and at a comfortable pace, so try not to rush them. You can help to build the confidence they need to take those first unaided steps by sitting a little distance away and, once they are standing and stable, opening up your arms and encouraging them to tak...

Similac - Baby's development: Month 11

Your baby is making big, new discoveries

My 11-month-old baby: keep baby-proofing your home

Your 11-month-old baby might explore your home more than ever before. He is probably cruising while holding on to furniture, standing (with a few wobbles), and fascinated with stairs he can climb up but not down. Consider taking new steps to protect him. Plus, keep talking to him and introducing simple concepts.

11-month-old baby developmental milestones

Keep in mind that every baby develops on a different schedule, bu...

Month 12

NutriciaProgram - Baby Month 12

As your baby's hand-eye co-ordination improves, they will gain much more control over their hands and fingers and become increasingly fascinated by 'cause-and-effect' actions, such as the turning of wheels that make toys move. Although they may be able to hold a spoon and try to feed themselves, their attempts will still be quite messy for some months to come.

Similac - Baby's development: Month 12

Your baby is growing up quickly

My 12-month-old baby: reaching milestones together

You and your baby have been together for one year, and she is developing a personality all her own. And she is developing quickly. She will soon experience the physical changes of becoming a toddler, so it is time to plan and prepare for her growing needs.

12-month-old baby developmental milestones

Your baby will develop at her own pace, which is completely normal. Here is a list of 12-month-old milestones your baby likely will...

Month 13

NutriciaProgram - Baby Month 13

During their second year, your toddler will develop rapidly, both physically and mentally. Walking, talking and growing all require iron – it's needed to carry oxygen around the body to your toddler's developing limbs, muscles, tissues and brain cells. Be prepared, if your toddler has yet to make his or her first toddling steps, it should happen soon.

Month 14

NutriciaProgram - Baby Month 14

One of the joys of watching your toddler grow is seeing more of their personality develop day by day. However, be warned: the more they learn about themselves, the fussier they can become! Often, the best opportunity toddlers get to exert their newfound independence is during mealtimes, and this is where you may find that a food they previously loved falls out of favor from one day to the next. Approximately half of all toddlers have fussy eating habits, which means there's a one in two chance of yours becoming a picky eater. So remember this is normal and you're not alone!

Month 15

NutriciaProgram - Baby Month 15

The first few years of a child's life are very important to the development of their immune system. As your baby becomes a toddler, they (and you!) will be out and about much more, going to nursery or toddler groups, making new friends and playing outside – all of which means exposure to new kinds of germs. This is perfectly natural and will help their immune system develop.

Let your child eat at their own pace and don't try and insist that the plate is cleared. Rushing your toddler through a meal puts pressure on them, which can reduce their appetite and come across as fussines...

Month 16

NutriciaProgram - Baby Month 16

As your toddler gets more independent and meets more people, their immune system will encounter new germs. Although picking up an occasional bug is a healthy sign that their immune system is getting the exposure it needs to develop, as a mother, you will want to help your toddler to avoid getting ill. Cleaning plastic toys or washing soft toys with hot water once a week will stop germs from building up.

With a little planning, there is no need to be concerned about your toddler's iron intake. Lean red meat provides iron in its most easily absorbable form. Dark green leafy vegeta...

Month 17

NutriciaProgram - Baby Month 17

Tantrums usually start after a child's second birthday – hence the term "the terrible twos" – but can start a little earlier. At this age, children are more independent and are beginning to think about what they want and don't want to do. Distracting a child with a toy or even something wildly fascinating you've just spotted outside the window is often all it takes. Experts advise avoiding the word "no", and saying "later" or "soon" instead.

Children often copy their parents, so try to stay calm if a tantrum is brewing. They'll progressively get the idea and will settle down by...

Month 18

NutriciaProgram - Baby Month 18

At 18 months, your toddler's language skills are starting to develop, and they will be able to understand most of the words you use, pairing up words more and more, such as 'me' and 'go'. Your toddler should have developed physical co-ordination, so they will now try to kick a ball and will dance to music and push and turn buttons and knobs.

Toddlers learn by copying things that you and others do. Be sure to help them understand why they should share, and the benefits it brings by sharing something with their other people or their friends.

Month 19

NutriciaProgram - Baby Month 19

At this age, your toddler has got lots and lots of energy, so provide at least one opportunity each day for him or her to run around outside. To power all that energy, your toddler needs a healthy balanced diet. You should be aware that your toddler is beginning to understand even more of the words that you use in front of him or her, and can tell when something is wrong.

Month 20

NutriciaProgram - Baby Month 20

Although your toddler seems more and more like a mini-adult every day, they still have a lot of growing up to do and their nutritional needs are still different from ours. They need three times more energy than an adult, yet their tummy is three times smaller, which means that every mouthful counts.

Also, do be aware that at this age, your toddler imitates almost everything he or she sees – hence, make sure that your child is not picking up any form of violent behavior, such as biting, pushing and hitting.

Month 21

NutriciaProgram - Baby Month 21

You may be taken aback to find your once-docile baby becoming aggressive with you and other children. Biting, hitting and pushing are common, and may be carried out for a variety of reasons. Sometimes it's experimental, sometimes it's because your child wants to feel more important. However the situation turns out, do not react by hitting your child as this will demonstrate that hitting people is okay. At this stage, your toddler may also become fussy at mealtimes and you might find that most of his or her food will end up on the floor. In spite of this, never force your toddler to eat a certa...

Toddler Development: 21 to 23 months

Learn about your 21 month old's development milestones and the importance of play and toddler games.

It’s amazing to watch your child become more coordinated, independent, attentive and aware of the world around him. As he enters his 21st month, you’ll see those skills becoming even more refined and polished.

The work of toddler play. At this age, playing is how your toddler learns about behaving in the world. He may be self-centered right now, but he’s slowly mastering the social skills he’ll use later on. Your toddler is starting to understand simple commands, w...

Month 22

NutriciaProgram - Baby Month 22

You may be wondering when is the right time to move your toddler from cot to bed. The truth is, there are no set rules for doing so. Many parents switch their child to a bed when they feel they have outgrown their cot, or the arrival of another baby is also a common reason to make the change.

To mark the occasion as a special event, and help your toddler feel excited about the big move from cot to bed, let them choose their own bedding. Get your child involved in setting up the bed and packing up the cot

Month 23

NutriciaProgram - Baby Month 23

Your toddler should be ready to start potty training around 18 to 24 months. However, just like most other things, there are no set rules. Some toddlers may not ready to start potty training until they are at least three years old. Mastering the steps of potty training may take a long time. While some toddlers will master it in just a few days, others may need weeks or even months.

Whether you use a potty or move straight to the toilet is also a personal decision, for if your child is prepared to sit on the toilet, then there is no need for a potty. Find out what works best for...

Month 24

NutriciaProgram - Baby Month 24

As your toddler becomes increasingly active and independent, they will need key nutrients for growth. But making sure that they get all the vitamins and minerals they need from their food each day can be a challenge, especially if they are going through a fussy eating phase.

At this stage, your two-year-old will need a wide variety of foods. Planning your menu ahead of time, including the day's snacks and drinks, will help to ensure your toddler gets a varied diet.

2-Year Checkup: Your Toddler at 2 Years

The 2-year checkup is coming up. Many parents find this visit more enjoyable than previous ones, as 2-year-olds tend to be interested in the exam and more talkative. Get the details on this checkup.

This visit will probably go more smoothly than the 18-month one because your 2-year-old will be more interested in the whole business. It's easier and more enjoyable for her to talk to the doctor or nurse who examines her.

At this visit, your provider will probably:

- Weigh and measure your baby.
- Provide insights into your child's physi...

Month 30

2.5 year old: what to expect

Are you the lucky parent of a 2 1/2-year-old? What milestones should you be looking for in your 30 months old and how can you help her develop her language, imagination and even fine motor skills?

The 30 month-old is delightful, often funny, and fun to be around.

Language.

She's discovering the power of words and has begun commenting on things in her environment just for the joy of sharing and talking. Encourage theseconversations, and give her lots of help when she gets stuck on words she's still struggling to get out. At this age she can form sentences...

Month 36

Good eating habits for a 3 year old

Simple guidelines to establish good toddler eating patterns and make family mealtime fun.

Your three-year-old is more willing to try new foods than he was last year. He's certainly more open to accepting foods presented in a new or interesting way. Unleash your creativity and make mealtime about fun, family and building lasting traditions.

Eating together as a family.

Three-year-olds learn so much about eating and socializing at the dinner table. Studies show that children who eat at least one meal a day with their families have better vocabularies, as we...

Baby Development Stage > Baby

Newborn

Similac - Baby's development: Month 1

My newborn baby: a whole new world

Newborn baby sleep patterns and tips

NutriciaProgram - Baby Week 1

NutriciaProgram - Baby Week 2

NutriciaProgram - Baby Week 3

NutriciaProgram - Baby Week 4

NutriciaProgram - Baby Week 5

NutriciaProgram - Baby Week 6

NutriciaProgram - Baby Week 7

Month 2

Similac - Baby's development: Month 2

My 2-month-old baby: a more familiar world

2-month-old baby sleep patterns and tips

NutriciaProgram - Baby Week 8

NutriciaProgram - Baby Week 9

NutriciaProgram - Baby Week 10

NutriciaProgram - Baby Week 11

Month 3

NutriciaProgram - Baby Week 12

Similac - Baby's development: Month 3

My 3-month-old baby: full of discoveries

3-month-old baby sleep patterns and tips

NutriciaProgram - Baby Week 13

NutriciaProgram - Baby Week 14

NutriciaProgram - Baby Week 15

Month 4

NutriciaProgram - Baby Week 16

Similac - Baby's development: Month 4

My 4-month-old baby: a sound foundation

4-month-old baby sleep patterns and tips

NutriciaProgram - Baby Week 17

NutriciaProgram - Baby Week 18

NutriciaProgram - Baby Week 19

Month 5

NutriciaProgram - Baby Week 20

Similac - Baby's development: Month 5

My 5-month-old baby: growing stronger, and wary of strangers

NutriciaProgram - Baby Week 21

NutriciaProgram - Baby Week 22

NutriciaProgram - Baby Week 23

Month 6

NutriciaProgram - Baby Week 24

Similac - Baby's development: Month 6

My 6-month-old baby: new ways to play and teach

6-month-old baby sleep patterns and tips

NutriciaProgram - Baby Week 25

NutriciaProgram - Baby Week 26

Month 7

NutriciaProgram - Baby Month 7

Similac - Baby's development: Month 7

My 7-month-old baby: your baby's growing world

7-month-old baby sleep patterns and tips

Month 8

NutriciaProgram - Baby Month 8

Similac - Baby's development: Month 8

My 8-month-old baby: moving in big, new ways

8-month-old baby sleep patterns and tips

Month 9

NutriciaProgram - Baby Month 9

Similac - Baby's development: Month 9

My 9-month-old baby: learning to grab, bang, and throw

9-month-old baby sleep patterns and tips

Month 10

NutriciaProgram - Baby Month 10

Similac - Baby's development: Month 10

My 10-month-old baby: Handling baby's new emotions and abilities

10-month-...

Month 11

NutriciaProgram - Baby Month 11

Similac - Baby's development: Month 11

My 11-month-old baby: keep baby-proofing your home

11-month-old baby developmental milestones

Month 12

NutriciaProgram - Baby Month 12

Similac - Baby's development: Month 12

My 12-month-old baby: reaching milestones together

12-month-old baby developmental milestones