The CDC milestone checklists describe what most babies, meaning 75 percent or more, can do by a given age. They are a conversation starter for your pediatrician visits, not a test to pass. [1]
By 4 months, most babies smile on their own to get your attention, and chuckle when you try to make them laugh. The full belly laugh is usually still ahead. Your baby also coos with sounds like "oooo" and "aahh", makes sounds back when you talk, and turns toward the sound of your voice. [1]
On the movement side, most 4 month olds hold their head steady without support when held, grip a toy placed in their hand, swing an arm at dangling toys, bring their hands to their mouth, and push up onto their elbows and forearms during tummy time. A hungry 4 month old will often open their mouth at the sight of the breast or bottle. Many also discover their own hands and study them with real interest. [1]
That push-up position is the runway to rolling. The strength and coordination for rolling usually appear at about five months, and most babies roll from stomach to back before they manage the reverse. [2] First rolls tend to arrive without warning, so keep a hand on your baby during diaper changes on any raised surface.
For the whole 4 to 12 month stretch, the recommended total is 12 to 16 hours of sleep per 24 hours, including naps. [3] Where those hours land varies a lot from baby to baby, and that variation is normal.
Around this age, many families hit a bump. A baby who had started sleeping in longer stretches begins waking at night again. Parents usually hear this called the 4 month sleep regression. The calm explanation: babies do not have regular sleep cycles until about 4 months of age. [4] Your baby is building a more mature sleep pattern, and extra waking often shows up while that new pattern settles. Nothing you did caused it, and it passes.
What helps, per the American Academy of Pediatrics: from 4 months on, put your baby down when drowsy but still awake, so falling asleep in the crib becomes a practiced skill. Keep night feedings and changes calm, quiet, and dim. Save the talking and play for daytime, which nudges longer sleep toward the night. [4]
Safe sleep rules still apply at every nap and every night: on the back, on a firm, flat surface, with no loose blankets or soft objects in the crib. [5] And with rolling on the horizon, one safety rule matters this month: stop swaddling as soon as your baby shows any sign of trying to roll over. [6] A sleep sack that leaves the arms free is a fine substitute. [6]
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Open the calculatorBreast milk, formula, or a mix: each one is a workable path at this age, and the practical numbers below cover all three. What matters most is that your baby is fed responsively and growing along their curve.
Most exclusively breastfed babies at this stage feed every 2 to 4 hours on average, though some feed more often and some go longer, and the CDC advises following your baby's hunger cues rather than the clock. [7]
Formula-fed babies average about 2 and a half ounces (75 mL) of formula per pound of body weight per day, and should usually drink no more than about 32 ounces (960 mL) in 24 hours. By 6 months that typically looks like 6 to 8 ounces at each of 4 or 5 feedings. [8]
One quiet task to keep up: vitamin D. Babies who receive only breast milk, or breast milk plus formula, need a daily supplement of 400 IU of vitamin D. Babies fed only formula, drinking 32 ounces (960 mL) or more per day, do not need the drops, because formula is already fortified. [9]
Solid foods are not on the menu yet. The Dietary Guidelines for Americans and the American Academy of Pediatrics recommend introducing foods other than breast milk or formula at about 6 months, and introducing them before 4 months is not recommended. [10] You have roughly two months to enjoy the simplicity.
Most of what you will notice this month is ordinary development doing its thing. A few signs deserve a call, so you never have to wonder.
By 4 months, talk with your child's doctor if your baby does not hold their head steady when held, does not bring hands to mouth, does not push up onto elbows or forearms during tummy time, does not coo or make sounds, does not smile at people, or has lost skills they once had. Ask about developmental screening. Acting early matters more than waiting to be sure. [1]
A rectal temperature over 100.4 F (38 C) counts as a fever. Call the doctor if a fever rises above 104 F (40 C) repeatedly, if your baby has had a seizure, if your baby cannot take in fluids, or if your baby still seems sick after the fever comes down. [13]
Watch for dehydration: fewer than six wet diapers in a day, a parched or dry mouth, fewer tears when crying, a sunken soft spot on the head, or playing less than usual. The AAP advises notifying the pediatrician right away if any of these develop. Signs of more severe dehydration, such as sunken eyes or excessive sleepiness, need prompt care. [14]
LEELALU is education, not medical care. Nothing here is a diagnosis. For anything on this list, or any symptom that worries you, contact your provider. If it feels like an emergency, call 911.
The stretch between 4 and 6 months is loud in the best way. By 6 months, most babies laugh for real, take turns making sounds with you, blow raspberries, and squeal. On the movement side, most roll from tummy to back, push up with straight arms, and lean on their hands to sit with support. [15]
Around 6 months, solid foods enter the picture, so the next few weeks are a good time to read up and relax about it. [10] The 6 month checkup also carries its own round of routine vaccines on the CDC schedule. [12]
The change is real, and it is developmental. Babies do not have regular sleep cycles until about 4 months of age, so extra night waking often shows up while that new pattern settles. [4] Total sleep needs stay the same: 12 to 16 hours per 24 hours, including naps, across the whole 4 to 12 month stretch. [3]
By 4 months, most babies chuckle when you try to make them laugh, though it is not yet a full laugh. [1] Full laughs typically arrive by 6 months. [15] If your baby is more of a quiet smiler right now, that is within the normal range too.
The skills that lead to rolling usually appear at about five months, and most babies roll from stomach to back before the other direction. [2] Because first rolls can come without warning, stop swaddling as soon as your baby shows any sign of trying to roll. [6]
LEELALU is education, not medicine. This page cannot diagnose or treat anything, and it never replaces your clinician. For anything on the "call your doctor" list, or anything that worries you, contact your provider. Found an error? Write to hello@leelalu.com and a person will read it. Our method: Editorial Standards.