Baby week by week · 3–6 months · 5–6 months: exploring

Your baby at 21 weeks

From Brittany Ryan, Founder and Mom of Two

What’s happening at about 4 months

Your baby may be making more sounds, experimenting with different pitches, and "talking" throughout the day. They are learning that communication is a two-way exchange, even before they understand words.

What’s ahead

The months ahead may bring rolling, sitting, first foods, and even more opportunities for adventure. It's amazing how quickly these little changes add up.

A memory to keep this week

A sitting-practice moment

Safety first

Use close adult supervision for every activity. For sleep, follow current safe-sleep guidance and use a firm, flat approved surface. Keep small parts, cords, button batteries and magnets out of reach.

In the app this week

Try this together: Narrate Your Day, plus this week's memory prompts, a private journal and your Journey, quick logs for firsts like practiced sitting and passed a toy. One simple idea at a time, never 47.

Become a Founding Mom Join the launch list

Guided by: CDC milestones + AAP (HealthyChildren.org) + CPSC, written in Brittany's words.

Every pregnancy and every baby is different. This is general, educational information, not medical advice. If something worries you, check with your provider or pediatrician.

Meet our founder

Brittany Ryan

Founder and Mom of Two

Brittany is a mom of two with a background in early childhood development. Little by Little Together began with a beautiful, blank baby book. Like so many parents, she bought baby books with every intention of filling them; instead, they sat in a closet while life kept moving. So she built a personal assistant for parenthood that tells you what matters right now, offers one simple idea at a time, and keeps your story safe.

“You don’t have to remember everything at once. Little by little, there is a story worth keeping.”

Read Brittany's story

Founding 500 · applications open until Mother's Day 2027

Help shape the app as a founding mom

Open to moms and expecting moms across the US. Brittany reads every application; selected founding moms get Plus access. Fields marked * are required.

First name *

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Your stage *

Why would you love to be a founding mom? *

I’m 18 or older, I’m a mom or expecting mom, and I live in the US. * I agree to the Founding 500 application terms (Draft, pending legal review), including Plus access for five years if selected. * I give Little by Little Together permission to use the introduction and other content I choose to submit to the Founding 500 program, with my first name, for app improvement and marketing. This includes publishing, editing for length without changing my meaning, and distribution across the brand’s website, social channels and app materials. Monthly check-ins are optional. This permission does not include my private in-app memories. * Send me launch news and sneak peeks. I can unsubscribe anytime. (Optional)

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