At four months old, your baby is becoming noticeably more social and physically active. This is the age when many babies start laughing out loud, reaching for toys, and beginning to roll over. Every baby develops on a slightly different timeline, but there’s a general set of skills most four-month-olds are working on or have recently mastered.
Social and Communication Skills
Four months is when your baby’s personality really starts to show. Most babies this age smile spontaneously, especially at people, and some have started laughing. Your baby likely coos and babbles, making vowel-like sounds (“ooh” and “aah”) and may try to imitate sounds you make. They’ll turn their head toward your voice and watch your face closely during conversations.
You’ll also notice your baby using crying in more distinct ways now. Different cries signal hunger, tiredness, or discomfort, and by this point many parents can tell them apart. Some babies this age begin to fuss or cry when play stops, a sign they’re starting to understand social interaction and want it to continue.
Movement and Motor Skills
The biggest physical developments at four months involve head control and the beginnings of rolling. Your baby can likely hold their head steady without support when held upright, and during tummy time they should be pushing up onto their forearms, lifting their chest off the floor. Some babies start rolling over around this age, typically from stomach to back first. Rolling from back to stomach usually comes later, closer to five or six months, though doing it in reverse order is perfectly normal.
Your baby’s hands are becoming much more purposeful. They’ll reach for and grasp toys, bring objects to their mouth, and may shake a rattle. You might notice them clasping their hands together or batting at dangling toys. These are early signs of hand-eye coordination that will keep refining over the coming months.
How Much Tummy Time They Need
By four months, your baby should be getting well beyond the starter sessions recommended for newborns. The NIH recommends that by two months, babies get 15 to 30 minutes of total tummy time per day, so at four months you can aim for even more. You don’t need to do it all at once. Spread it across several sessions throughout the day, building up from 3 to 5 minutes at a time to longer stretches as your baby tolerates it. Tummy time strengthens the neck, shoulder, and arm muscles your baby needs for rolling, sitting, and eventually crawling.
Feeding at Four Months
Whether breastfed or formula-fed, your baby is still getting all their nutrition from milk at this age. Most four-month-olds eat about 4 to 6 ounces per feeding, roughly every 3 to 4 hours. By six months, that amount typically increases to 6 to 8 ounces across 4 or 5 feedings per day. Breastfed babies tend to take in slightly smaller amounts more frequently, since breast milk is digested faster than formula.
You may be wondering about starting solid foods. Four months is the earliest age solids can be introduced, but most pediatricians recommend waiting until closer to six months. The key is watching for readiness signs rather than going strictly by age. Your baby is ready when they can sit with support, hold their head steady, open their mouth when offered food, and swallow food instead of pushing it back out with their tongue. If your baby isn’t doing all of these things yet, they’re not ready for solids, and that’s completely normal at four months.
Sleep Patterns
Most four-month-olds sleep around 12 to 16 hours total in a 24-hour period, including naps. Daytime sleep typically settles into at least two naps, one in the morning and one in the early afternoon, with some babies still needing a shorter late-afternoon nap. Nighttime stretches are getting longer, and some babies this age sleep 6 to 8 hours without waking, though plenty still wake once or twice to feed.
This is also the age many parents notice what’s often called the “four-month sleep regression,” a period where a baby who previously slept well suddenly starts waking more frequently. This happens because your baby’s sleep cycles are maturing and becoming more like adult sleep, with lighter stages that make them more likely to wake between cycles. It’s temporary, typically lasting two to four weeks.
Vision and Awareness
Your baby’s vision has improved significantly since birth. At four months, they can see across a room and track moving objects smoothly with their eyes. Color vision is developing, and babies this age are particularly drawn to bold, contrasting colors. You’ll notice your baby studying faces intently and recognizing familiar people from a distance. They may also start looking at their own hands with fascination, turning them over and examining their fingers.
Vaccines at the Four-Month Visit
The four-month well-baby checkup includes the second round of several routine vaccines. Your baby will typically receive their second doses of vaccines protecting against diphtheria, tetanus, and whooping cough (DTaP), as well as vaccines for Hib disease, polio, pneumococcal disease, and rotavirus. These are all second doses, building on the first round given at two months. Your pediatrician will also measure your baby’s weight, length, and head circumference to track their growth curve.
Signs Worth Mentioning to Your Pediatrician
Babies develop at their own pace, and being a little ahead or behind on one skill isn’t usually a concern. But certain patterns are worth bringing up with your doctor: if your baby doesn’t watch things as they move, doesn’t smile at people, can’t hold their head steady, doesn’t coo or make sounds, doesn’t bring things to their mouth, or doesn’t push down with their legs when their feet are placed on a hard surface.
Losing a skill your baby previously had is always worth mentioning. If your baby used to coo and has stopped, or could hold their head up and no longer seems able to, bring that up at your next visit. The CDC recommends acting early with any concerns rather than waiting to see if your baby “catches up” on their own. Early evaluation doesn’t mean something is wrong. It means you’re giving your baby the best chance to get support if they need it.