Week 12 old
Week 12 marks the end of month 3: longer feeds, more predictable sleep, and a more social, smiley baby. Here's what's typical and what to watch for.
In short
At 12 weeks, many babies feed every 3-4 hours (about 24-32 oz of formula a day or nursing on demand), sleep around 14-16 hours total with longer night stretches, and are increasingly alert, smiley, and vocal.
🍼 Feeding
Roughly every 3-4 hours: about 4-6 oz of formula per feed (around 24-32 oz a day), or nursing on demand 6-8 times in 24 hours. No solids yet — most babies aren't ready until around 6 months.
😴 Sleep
About 14-16 hours total, often 9-10 hours overnight (with feeds) plus 3-4 daytime naps. Wake windows are typically around 1.5-2 hours. Always place baby on the back, on a firm flat surface, with no loose bedding, pillows, or bumpers.
What's happening this week
- •Around this age, many babies hold their head steadier during tummy time and may push up on their forearms.
- •Hands open more often now, and many babies start swiping at or grabbing dangling toys.
- •Social smiles and cooing are common around now, and some babies start to laugh.
- •Many babies are more interested in faces, voices, and tracking objects across the room.
Milestones to keep in mind
- ✓By the 4-month checkup, many babies hold their head steady when upright and may push up on their elbows during tummy time — week 12 is the lead-up to that range.
- ✓Around now, many babies smile to get your attention and coo back when you talk to them.
- ✓Some babies bring hands to mouth and reach for toys, though the exact timing varies widely from baby to baby.
Growth
💡 Tip for this week
Build in short, daily tummy-time sessions while baby is awake and supervised — a few minutes several times a day helps strengthen neck and shoulder muscles for the months ahead.
⚠️ When to call your pediatrician
Call your pediatrician for a fever of 100.4°F (38°C) or higher, fewer than 6 wet diapers a day, poor feeding or no weight gain, or persistent floppiness or stiffness. Also mention it if, by the 4-month checkup, your baby isn't making eye contact, smiling socially, or responding to sounds. Trust your instincts and reach out with any worry.
Frequently asked
How much should a 12-week-old eat?
Many 3-month-olds take about 4-6 oz of formula every 3-4 hours (roughly 24-32 oz a day), or nurse on demand 6-8 times in 24 hours. Babies vary, so follow your baby's hunger and fullness cues.
Should my 12-week-old be sleeping through the night?
Some babies start sleeping longer stretches around now, but many still wake to feed at night, and that's completely normal. Night waking at 12 weeks is not a sign of a problem.
Is it normal for my 3-month-old to smile and coo?
Yes — social smiles and cooing are common around this age, and some babies even start to laugh. If your baby isn't smiling or making sounds by the 4-month checkup, mention it to your pediatrician.
Looking for the bigger picture? See the month 3 overview →
General guidance, not medical advice. Every baby develops at their own pace — talk to your pediatrician with any concerns.