Week 15 old
Week 15 of your baby's first year: more predictable feeds, longer night sleep stretches, and lots of grabbing and "talking." Here's what's typical around 3.5 months.
In short
At 15 weeks, most babies take in about 25-32 oz of milk a day across 5-7 feeds and sleep roughly 14-16 hours total, often with one longer stretch at night and 3-4 naps. Development is best measured against the 4-month checkup, not week by week.
🍼 Feeding
About 25-32 oz of milk per day: roughly 5-7 breastfeeds, or 4-6 oz of formula every 3-4 hours. Most babies this age are not ready for solids yet — most start closer to 6 months.
😴 Sleep
Around 14-16 hours total: typically 3-4 naps with wake windows of about 1.5-2 hours, plus a longer night stretch (often 5-8 hours for some babies, though night wakings are still completely normal). Always place baby on the back to sleep, on a firm flat surface with no pillows, blankets, or bumpers.
What's happening this week
- •Around this age, many babies hold their head steady and push up on their forearms during tummy time.
- •Hands are opening up — lots of babies start batting at and grabbing toys, and bringing hands (and everything else) to the mouth.
- •Babbling and cooing often pick up now, with squeals and back-and-forth 'conversations' when you talk to them.
- •Many babies are drawn to bright colors and faces and may turn toward sounds and voices.
Milestones to keep in mind
- ✓The next official check-in is the 4-month checkup — around there, the CDC notes many babies smile to get your attention, coo, and hold their head steady when held.
- ✓By the 4-month visit, many babies push up on their elbows during tummy time and bring hands to mouth — but the timing varies widely from baby to baby.
- ✓Some babies show early signs of rolling around now; others take several more weeks, and both are normal.
- ✓Milestones are ranges, not deadlines — bring any questions to the 4-month checkup rather than worrying about a specific week.
Growth
💡 Tip for this week
Protected, supervised tummy time in short, frequent sessions builds the neck and shoulder strength behind rolling and sitting — aim for a little play on the floor several times a day while baby is awake and alert.
⚠️ When to call your pediatrician
Call your pediatrician if you notice fewer than 5-6 wet diapers a day, poor feeding or no weight gain, a fever of 100.4°F (38°C) or higher, unusual floppiness or stiffness, no response to loud sounds, or that your baby still can't hold their head up at all — and always trust your gut and call if something feels off.
Frequently asked
How much should a 15-week-old eat?
Most babies around 15 weeks take in about 25-32 oz of milk a day — roughly 5-7 breastfeeds, or 4-6 oz of formula every 3-4 hours. Appetite varies, so follow your baby's hunger and fullness cues.
Can my baby start solids at 15 weeks?
Usually not yet. Most babies are ready for solids closer to 6 months, once they can sit with support and hold their head steady. Talk to your pediatrician before starting, especially before 6 months.
Is it normal for a 15-week-old to still wake at night?
Yes. While some babies start sleeping 5-8 hour stretches around this age, frequent night waking is still completely normal at 15 weeks. Keep night feeds calm and low-light, and always put baby back to sleep on the back.
Looking for the bigger picture? See the month 4 overview →
General guidance, not medical advice. Every baby develops at their own pace — talk to your pediatrician with any concerns.