Week 3 old
What to expect at 3 weeks old: feeding amounts, sleep totals, and the normal newborn fussiness that often ramps up around now. Reassuring, range-based guidance for month 1.
In short
At 3 weeks old, most babies are feeding 8 to 12 times a day, sleeping 14 to 17 hours total in short stretches, and many start to seem fussier in the late afternoon and evening. This is a normal, demanding newborn phase, and your baby has likely passed their birth weight by now.
🍼 Feeding
Most 3-week-olds eat 8 to 12 times per day. Breastfed babies typically nurse every 2 to 3 hours, including night feeds and clusters in the evening. Formula-fed babies usually take about 2 to 3 ounces per feeding, often totaling roughly 19 to 24 ounces a day. Feed on demand and watch for early hunger cues (rooting, hand-to-mouth) rather than the clock; expect at least 6 wet diapers a day once feeding is well established.
😴 Sleep
Babies this age sleep about 14 to 17 hours per 24 hours, spread across many short stretches of roughly 2 to 4 hours, day and night. There is no fixed nap count yet. Wake windows are very short, often only 45 to 60 minutes including a feed. 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 newborns become noticeably more alert during brief awake windows and may briefly fix on a face or high-contrast object 8 to 12 inches away.
- •Fussiness and cluster feeding often pick up around weeks 2 to 3 as babies grow quickly; this is common and usually peaks closer to 6 weeks.
- •Many babies this age make small throaty and cooing sounds and turn toward familiar voices, though startle (Moro) reflexes are still very active.
- •During supervised tummy time, some babies briefly lift and turn their head to the side, building the neck strength tracked at the 2-month checkup.
- •Sleep is still driven by hunger rather than day or night, so a settled routine is not expected yet.
Milestones to keep in mind
- ✓By the 2-month checkup, many babies briefly lift their head during tummy time and begin to smile in response to you, but these vary widely from baby to baby.
- ✓Around now, many babies start to calm when picked up, held, or spoken to, though this is gradual and not constant.
- ✓Many newborns this age can briefly focus on faces and follow a slow-moving object part of the way; full smooth tracking develops over the coming weeks.
- ✓Remember there are no official per-week milestones in early infancy; the CDC's first checkpoint is at 2 months, so treat these as broad ranges, not deadlines.
Growth
💡 Tip for this week
Evening fussiness often intensifies around now. Try the calming basics one at a time: skin-to-skin holding, gentle motion, a quiet dim room, and offering a feed. If you ever feel overwhelmed by crying, it is always okay to lay your baby safely on their back in the crib and step away for a few minutes to reset.
⚠️ When to call your pediatrician
Call your pediatrician promptly for a rectal temperature of 100.4°F (38°C) or higher in a baby this young, fewer than 6 wet diapers a day or signs of dehydration (very few wet diapers, sunken soft spot, no tears, lethargy), poor feeding or refusing to eat, no weight gain or weight loss, a yellow tint to the skin or eyes that is worsening, forceful or projectile vomiting, blood in stool, persistent inconsolable crying, or a baby who is unusually hard to wake or floppy. When in doubt about a newborn, call.
Frequently asked
Why is my 3-week-old suddenly so fussy and feeding constantly?
Increased fussiness and cluster feeding are very common around weeks 2 to 3, often tied to a growth spurt. Frequent nursing or bottles help boost your supply and meet your baby's needs. It is exhausting but usually normal; mention it to your pediatrician if your baby seems unwell, is not having enough wet diapers, or is not gaining weight.
How much should a 3-week-old eat?
Most eat 8 to 12 times a day. Breastfed babies nurse every 2 to 3 hours on demand; formula-fed babies often take about 2 to 3 ounces per feeding. Follow your baby's hunger cues rather than a strict schedule, and use steady weight gain and at least 6 wet diapers a day as signs they are getting enough.
Is it normal that my 3-week-old has no sleep schedule?
Yes. At 3 weeks, sleep is driven by hunger, not the time of day, so short, unpredictable stretches around the clock are completely normal. A more day-night pattern usually starts to emerge in the coming weeks. For every sleep, place your baby on their back on a firm, flat surface with nothing loose in the crib.
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.