Developmental Milestones

By: Nicole Hamp, MD, Amy Nasamran, M.A & Suzi Naguib, Psy.D.

Infants and toddlers are quickly learning new things every day. They are learning about their senses, how to move about the world, and how to communicate and speak. There are so many exciting things to see as a child develops. Let’s walk through what typical early development looks like.

2 Months At around 2 months of age, babies start to laugh and coo. Cooing is the adorable vowel sounds a baby makes (e.g., “oooo,” “ahhh”). Also around this time, babies will start to turn their heads in the direction of sound.

4 Months By around 4 months, babies begin to show interest in watching other people’s faces and may also reciprocate a smile. They may also start to add consonant sounds to their vocalizations (e.g., “a-ba,” “a-da”).

6 Months At approximately 6 months babies begin to sit with minimal support. They also smile while playing, respond to their name when called, cry/make sounds to show displeasure, and babble to show joy. Babbling is similar to cooing but involves stringing together consonant sounds (e.g., “ba-ba-ba,” “da-da-da”).

9 Months At around 9 months babies begin to crawl around the room and use their finger to point at things in their environment. They also reciprocate smiles and other facial expressions and start to sound like they may be saying their first words. That is because at this stage in development babies begin to use double consonant sounds (e.g., mama, dada, baba, etc.). However, these double consonant sounds at this stage are nonspecific and do not yet carry a meaning.

12 Months At about 12 months, babies typically start using “mama” and “dada” with meaning (calling “mama” to mean mom and “dada” to mean dad). Babies at this age are also expected to start to saying other single words such as ball, go, and milk, use simple gestures (waving goodbye, pointing to request), and give objects to ask for help (handing a book to request a story be read). Babies also begin to walk while holding on to furniture during this time.  

15 Months Between 12 months and 15 months, it is common to see a dramatic increase in receptive vocabulary (i.e., understood language). During this time period babies also begin “jargoning.” This is when a toddlers begins to use speech with some tone and rhythm, although not all of their words will be comprehensible. Toddlers at this age also begin shaking their head to mean no or nodding their head to mean yes.

18 Months By 18 months, most toddlers are walking without help and can engage in simple pretend play, such as feeding a doll or a stuffed animal. Toddlers will use and understand at least 10 different words, including “yes,” “no,” and other words to express their needs. Between 18-24 months, toddlers are rapidly learning new words and go through what is often called a “language explosion,” which is a term used to describe a time period when their use and understanding of language increases dramatically.

24 Months By 2 years of age, toddlers often have approximately 200 words in their vocabulary and are also expected to be putting 2-4 words together to form simple phrases. In addition to being able to ask simple questions, they are also able to follow two-step directions. During this time children are also engaging in more pretend play, such as feeding and putting the doll to sleep.

3 Years At approximately 3 years old, children typically have a vocabulary of roughly 1,000 words and are putting 4-5 words together to form sentences. They are now able to talk about interests and feelings about the past and the future.

4 Years By 4 years, children are expected to be speaking intelligibly. However, they may still pronounce harder speech sounds (e.g., “th” and “sp”) differently until about 8 years old.

What if my child is not meeting the above milestones?
The above milestones are approximations, and not all children follow this exact same trajectory. Some children may not meet their developmental milestones on time. This is not always a problem, but it is always worth a conversation with your pediatrician. Your pediatrician will help to determine if further evaluation and intervention is necessary.

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