5 Key Social and Communication Milestones to Watch for at 4–5 Months

Wondering what your baby should be doing around four or five months? It’s a tender, exciting age—and also a critically important one for developmental foundations. In this post, I’ll walk you through five simple, meaningful behaviors to be watching for in your baby that relate to early social and communication milestones. These are the signs that help us understand how your child is connecting, responding, and engaging with the world—and they matter more than most people realize.

You're not alone if you're unsure what “counts” as typical development at this stage. Most parents haven’t been taught what to look for—but once you see these tiny building blocks, you’ll understand why they matter so much down the line.

A Simple Start: Watch and Listen for These 5 Signs

Here are five approachable signs you can begin watching for in your baby right now, even in the course of a regular day:

1. Does your baby smile to get your attention? Not just smiling in general—but actively using smiles as a way to engage with you.
2. Do they seek you out visually? That means turning to look at you, meeting your gaze, or scanning for you when you're nearby.
3. Are they vocalizing to engage? Listen for little sounds like “ah!” or “ooh!”—these are early efforts to connect.
4. Do they make sounds back to you while you’re talking? This back-and-forth, even with pre-speech sounds, is an early form of conversation.
5. Will they turn their head when they hear your voice? That orientation is how babies begin tuning into social speech and learning from others.

If even one of these feels uncertain or missing for your baby, don’t panic. These are all skills you can support—and the earlier we notice them, the more we can do to help.

Why This Window Matters So Much

Every one of these signs falls under two core areas of development: social connection and language and communication. And these are exactly the areas that, when delayed, are most associated with a later diagnosis of autism.

That doesn’t mean a delay equals autism. But it does mean that careful observation in these areas gives us a head start. Early signals in social attention, reciprocity, and sound play help us notice when a child may benefit from extra support—even before age one.

And the science is clear: the earlier we recognize these signs, the more impact early support can have, thanks to how adaptable the brain is in the early years. Brain plasticity is at its peak in infancy—and that's our window for change.

Here’s How You Can Boost These Milestones

If a milestone isn’t showing up yet, or if it feels inconsistent, there are simple things you can do that help reinforce it.

• For shared smiling: Get face-to-face during cuddle time and pause after smiling—wait a few beats to see if your baby smiles back. Then respond warmly, reinforcing that shared joy.
• For making sounds: Copy their sounds! If your baby says “ooh,” you can echo with an “ooh!” right back. Add a little delighted tone to keep it engaging.
• To support turn-taking sounds: Set up little “conversations.” Say something short, pause, smile, and see what your baby offers. Then go again. This models two-way interaction.
• To encourage head-turning to voice: Try softly calling your baby’s name from different directions during play—and when they look, light up your face and talk or sing so it's a rewarding moment.

Think of these little interactions as seeds. You’re planting the roots of connection, attention, and communication that your child will build on for years to come.

What to Say During These Moments

Here are a few simple scripts I use and share with families to make these interactions feel easy and natural:

• “Hi there! Are you looking at Mama?” (Said with a smile when your baby turns toward you.)
• “Ooh!” “Ahh!” (Repeat their sounds right back with playfulness.)
• “You heard me! You're looking at me, wow!” (When they turn their head to your voice.)
• “You’re talking to me? I love when you talk to me!” (Said during cooing or sound exchanges.)

It doesn’t have to be perfect. Your warmth, responsiveness, and gentle repetition are what matter.

When to Seek More Support

If your baby isn’t showing some of these signs by 5 months, or if you're just not feeling confident in how their communication is unfolding, it’s okay to ask more questions. You are not overreacting. You are not being “too anxious.” You’re tuning in—and that’s exactly what attentive parenting looks like.

Many babies who go on to thrive had early delays that were caught and supported thanks to a parent paying attention. Development is not about perfection—it’s about momentum. And noticing early gives us more time to build that momentum intentionally.

Track All the Milestones with Confidence

If you want a simple way to monitor your baby’s development from 2 months up to 18 months, I created my free developmental milestones guide to give you clarity and peace of mind. It covers all four major categories of development and highlights which milestones are most associated with an autism diagnosis.

You can use it to gently keep track, see patterns, and know what to bring up with your pediatrician or early intervention provider if needed.

Want Personalized Support?

If you'd like more personalized support as you monitor your baby's development, you can schedule a free 30-minute discovery call with me to see if consultation is right for you and your family. We'll look at your unique questions and talk through next steps together—no pressure, just support.

FAQs About Developmental Milestones and Early Signs

How do I know if my 4-month-old is behind in communication?

Look for social and sound-based milestones: smiling to engage, making back-and-forth sounds, turning to your voice, and visually connecting. If those aren’t yet happening, it may be worth a deeper look—but early delays aren’t uncommon and can often be supported effectively.

Is it too early to think about autism at 4–5 months?

It's not about diagnosing autism this early—it’s about noticing patterns. Delays in social and language areas at this age don’t mean autism, but they are associated with later diagnosis. Early noticing helps us give your child the best developmental support possible.

My baby isn’t making many sounds yet—is that okay?

Every baby develops at their own pace, but by 4–5 months we expect to hear early social sounds like cooing and vowel-like noises. You can support this by modeling sounds and engaging in playful sound exchanges. If you’re concerned, getting input is never a bad idea.

What if my pediatrician said to wait and see?

It’s okay to trust your gut. You are the one spending every day with your baby—you’re noticing details others won’t see. Waiting is one approach, but seeking early screening or support never harms and often helps. You're allowed to ask for more.

Where can I get help understanding all the milestones?

You can download my free developmental milestones guide—it breaks down all the categories and flags the milestones most linked to developmental concerns, so you don’t have to do the guesswork alone.