Week 4 old
What to expect at 4 weeks old: your baby is nearing the 1-month mark. Feeding amounts, sleep totals, and early development at week 4, explained for new parents.
In short
At 4 weeks, most babies are eating more at each feed (around 3 to 4 oz, or nursing every 2 to 3 hours), sleeping 14 to 17 hours across the day and night in short stretches, and starting to be alert for slightly longer windows. Your baby is nearly one month old and likely back above birth weight.
🍼 Feeding
Breastfed babies typically nurse 8 to 12 times in 24 hours (roughly every 2 to 3 hours). Formula-fed babies usually take about 3 to 4 oz per feeding every 3 to 4 hours, often totaling around 24 to 32 oz per day. Feed on demand and watch hunger cues rather than the clock; many babies cluster-feed in the evening, which is normal.
😴 Sleep
Most 4-week-olds sleep about 14 to 17 hours total across a 24-hour day, broken into short stretches of roughly 2 to 4 hours with no fixed day-night rhythm yet. Wake windows are very short, often only about 45 to 60 minutes. Always place your baby on their back to sleep, on a firm flat surface, with no pillows, blankets, bumpers, or soft toys.
What's happening this week
- •Around this age many babies start having brief alert, awake periods where they'll study faces and high-contrast patterns held about 8 to 12 inches away.
- •Reflexes like the startle (Moro) and grasp reflexes are still strong now and are completely normal and expected.
- •Many 4-week-olds begin making small throaty cooing or gurgling sounds in addition to crying, though this varies widely from baby to baby.
- •Some babies start briefly lifting their head during tummy time around now, but plenty won't yet, and that's fine.
- •Crying often peaks somewhere around 6 to 8 weeks, so fussy evening stretches starting now are common and usually normal.
Milestones to keep in mind
- ✓Heading toward the 2-month checkup, watch for the first social smile (a real smile in response to you), which appears in many babies between roughly 6 and 8 weeks, not yet for most at 4 weeks.
- ✓Around this age many babies briefly focus on a face and may start to follow a slow-moving object with their eyes, though this is still developing.
- ✓Many babies begin to calm or quiet to a familiar voice or being held; this is emerging, not guaranteed, at 4 weeks.
- ✓By the 2-month visit your pediatrician will check head control, tracking, and early social responses, so think of week 4 as building toward those, not hitting them on schedule.
Growth
💡 Tip for this week
Keep tummy time short and frequent: a few 1 to 3 minute sessions a day while your baby is awake and supervised helps build neck and shoulder strength. Many babies dislike it at first, so start with your baby on your chest while you recline, and never leave them on their tummy unattended or for sleep.
⚠️ When to call your pediatrician
Call your pediatrician promptly if your baby has a rectal temperature of 100.4°F (38°C) or higher, since fever in a baby under 2 to 3 months always needs medical evaluation. Also call for fewer than 6 wet diapers a day, no weight gain or weight loss, poor feeding or refusing to eat, unusual sleepiness or difficulty waking, persistent vomiting (especially forceful or green), labored or fast breathing, or yellowing of the skin or eyes (jaundice) that is new or worsening. Trust your instincts and call if something feels off.
Frequently asked
How much should a 4-week-old eat?
Most formula-fed 4-week-olds take about 3 to 4 oz per feeding every 3 to 4 hours, totaling roughly 24 to 32 oz a day. Breastfed babies usually nurse 8 to 12 times in 24 hours. Feed on demand and follow hunger cues; amounts vary by baby, so ask your pediatrician if you're unsure.
Why does my 4-week-old cry so much in the evening?
Evening fussiness and cluster feeding are very common at this age. Infant crying tends to build over the first weeks and often peaks around 6 to 8 weeks before easing. Try feeding, holding, swaddling, gentle motion, and a calm dark room. If crying seems inconsolable or you're worried, never shake your baby and call your pediatrician for support.
Should my 4-week-old be smiling yet?
Not necessarily. The first real social smile typically appears between about 6 and 8 weeks, so most babies aren't smiling responsively at 4 weeks. Development happens in ranges. If your baby isn't smiling by the 2-month checkup, mention it to your pediatrician, but a quiet 4-week-old is completely normal.
Looking for the bigger picture? See the month 1 overview →
General guidance, not medical advice. Every baby develops at their own pace — talk to your pediatrician with any concerns.