4 Months Old: Milestones And Red Flags

At 4 months old, many babies are getting stronger, more social and more interactive. At this age, your baby may be able to hold their head steady, push up on their forearms during tummy time, reach for and hold toys, bring their hands to their mouth, and make more sounds like coos, squeals or little laugh-like noises.

That said, development is not identical from baby to baby. Some variation is completely normal. “Children develop at their own unique pace,” said Dr. Jessica Lynch, developmental pediatrician at Holland Bloorview Kids Rehabilitation Hospital. “There are also ranges for reaching developmental milestones.” If you have questions or concerns about how your baby is developing, check in with your doctor or healthcare provider.

Milestones

At 4 months old, babies are usually making progress across movement, communication and social development.

One of the biggest physical changes at this age is stronger head and upper-body control. “They should be able to lift their head and hold it up, and they may also be using their elbows and arms,” said Nadine Korah, Attending Physician in the Division of General Pediatrics at the Montreal Children's Hospital. Some babies may also start rolling from tummy to back.

You may also notice gains in fine motor development. At 3 months old, babies are working on grasping, and by 4 months old, many can reach for toys, hold on to them for a short time and bring their hands toward their mouth. “If they grab a toy, they should be able to hold it, and they may be able to shake it,” Dr. Korah said.

Communication and social milestones matter just as much. Many 4-month-olds are cooing, squealing, making repetitive sounds and reacting more clearly to familiar voices. They may smile to get your attention, laugh when you play with them and copy some facial expressions. Babies this age often watch faces closely and track people or objects with their eyes.

Quick 4-month milestones

• Holds their head steady without support
• Pushes up on their forearms during tummy time
• Reaches for toys and may hold or shake them
• Brings their hands to their mouth
• Coos, squeals or makes repetitive sounds
• Smiles and may laugh during play
• Watches faces and tracks people or objects with their eyes
• Responds to voices or sounds

Red flags to look for

Most babies do not hit every milestone at the same time, but some signs deserve a conversation with your doctor or healthcare provider sooner rather than later.

Movement

“At 4 months, if you notice your child isn’t holding their head up on their own, or is only reaching and grabbing with one hand, check in with your healthcare provider to assess their muscle tone,” suggested Dr. Jessica Lynch. Poor head control, seeming very floppy, seeming unusually stiff or always favouring one side of the body are all worth bringing up.

Hearing and communication

Responding to voices and everyday sounds is an important developmental marker at this age. If your baby is not making sounds, is not reacting to sound, or does not seem to respond when you talk to them, that is something to mention to your healthcare provider.

Social and visual development

“If your baby is not smiling by this time, this is also something that should be assessed,” Dr. Lynch said. It is also worth checking in if your baby is not following people or objects with their eyes, does not seem interested in faces, or is not engaging much with the people around them.

If you notice one of these signs, it does not automatically mean there is a serious problem. But it is a good idea to mention it at your next well-baby visit, or sooner if the concern seems pronounced or your instincts tell you something is off.

Fun age-appropriate activities

At 4 months old, babies benefit from lots of supervised tummy time, face-to-face play, and simple opportunities to reach, grasp and explore. This is around the age when many babies are figuring out how to push up more strongly and may start rolling, so floor play becomes especially useful.

“You can gently help them roll from side to side, coaching and guiding them,” Dr. Korah said. “If you want them to reach for things, put something like a toy in front of them that is slightly out of reach, so they have to work a bit to get it.”

You can also encourage development by talking, singing and reading aloud, especially books with high-contrast images or interesting textures. Toys such as rattles, soft books, mirrors and play gyms can help motivate your baby to watch, reach and bat at objects.

Avoid leaving your baby in things like bouncers or strollers for too long, and follow their lead. If they seem tired or overstimulated, it is time for a break.

What parents should do if they are unsure

If you're not sure whether your baby is on track, try looking for patterns over a few days instead of focusing on one moment. Babies can have off days, and development often shows up gradually.

If a milestone seems delayed, or your baby has a clear red flag such as poor head control, no response to sound, limited smiling or trouble tracking with their eyes, bring it up with your doctor, nurse practitioner or other healthcare provider.

You can also support development in simple everyday ways: make time for tummy time every day, talk and read to your baby, smile and respond to their sounds, and give them safe chances to reach, grasp and explore.