GUIDE
Newborns grow faster in their first 12 weeks than at any other time in their lives. Growth spurts at weeks 1-3, 6, and 10-12 drive most of the chaos.
The first three months of your baby's life are a whirlwind of feeding, sleeping, and growing. Your newborn will roughly double their birth weight by 4-5 months, and much of that happens in intense bursts. Here's what to expect week by week — so you can stop googling 'is this normal' at 3 AM.
Your newborn's first three months are the most intense period of growth they'll ever experience. They'll gain roughly 5-7 ounces per week, grow about an inch per month in length, and their brain will be growing so fast you can practically watch their head get bigger.
This growth doesn't happen at a steady, linear pace. It happens in bursts — intense periods of 2-5 days where your baby eats like they've never seen food before, sleeps erratically, and tests your patience. These are growth spurts, and they're a sign that everything is working exactly right.
The major newborn growth spurts typically happen around weeks 1-3, week 6, and weeks 10-12. But every baby is different — your baby might spurt a week early or late, or skip one entirely. The timeline below is a guide, not a contract.
| Week | Weight | Feeding | Sleep | What to Know |
|---|---|---|---|---|
| Week 1 | Initial loss of 5-10% birth weight (normal) | 8-12 feeds/day, colostrum transitioning to mature milk by day 3-5 | 16-18 hours/day in short bursts | Focus on feeding frequency, not schedule. Expect 1 wet diaper per day of life (1 on day 1, 2 on day 2, etc.). |
| Week 2 | Regaining birth weight — gaining 5-7 oz/week | GROWTH SPURT — feeding every 1-2 hours, cluster feeding begins | Still 16-17 hours but more night waking for feeds | First major growth spurt. Baby is placing orders for a bigger milk supply. This is intense but normal. |
| Week 3 | Steady gain of 5-7 oz/week | Still frequent — may ease slightly from the week 2 peak | Starting to have slightly longer sleep stretches (2-3 hours) | Growth spurt may continue or taper. Some babies have a distinct week 3 spurt. |
| Weeks 4-5 | Consistent gain, usually above birth weight now | 8-12 feeds/day, evening cluster feeding is common | May get one 3-4 hour stretch at night | A brief lull between spurts. Feeding starts to feel slightly more predictable — enjoy it. |
| Week 6 | Accelerated gain during the biggest early spurt | MAJOR GROWTH SPURT — feeding constantly, fussy at breast/bottle | Sleep disrupted, nap resistance, more night waking | The 6-week spurt is the most intense. Overlaps with peak fussiness period. Feels relentless. Lasts 3-5 days. |
| Weeks 7-9 | Steady gain of 5-7 oz/week | Feeds may space out slightly, 7-10 feeds/day | Improving — some babies start getting a longer night stretch | Recovery period after the 6-week spurt. Baby becomes more alert and social. First smiles appear. |
| Weeks 10-12 | Another acceleration for some babies | Possible growth spurt — increased feeds, fussiness | Variable — some disruption if spurting, improvement if not | Some babies have a clear 3-month spurt, others don't. By 12 weeks, many babies have nearly doubled their birth weight. |
tinylog makes feed logging fast — one tap to start, one tap to stop. When your pediatrician asks 'how often is the baby eating?' at the 2-week visit, you'll have an actual answer instead of a sleep-deprived guess.
These averages come from WHO growth standards. Your baby may gain more or less in any given week — what matters is the overall trend upward.
The most common worry during newborn growth spurts — especially for breastfeeding parents — is: "Do I have enough milk?"
The answer is almost always yes. When your baby feeds constantly during a growth spurt, they're not signaling that your supply is inadequate. They're building your supply. Breast milk works on a supply-and-demand system: more nursing = more milk production. The growth spurt is the demand signal; increased supply follows within 24-48 hours.
This is worth repeating because the anxiety is real: constant feeding during a growth spurt is not a sign of low supply. It's the mechanism that creates more supply.
For more on feeding frequency at each stage, see our baby feeding chart or our cluster feeding guide.
When your newborn wants to eat every hour during a growth spurt, it can feel like your milk isn't enough. The opposite is true — frequent nursing is exactly how your body knows to make more milk. Supply and demand. The more your baby nurses, the more your body produces. This system works.
At birth, your baby's stomach is the size of a marble (5-7ml). By day 3, it's a ping-pong ball (22-27ml). By day 10, it's an egg (60-80ml). Frequent small feeds in the first week aren't a sign of hunger — they're a reflection of tiny stomach capacity.
Before your milk 'comes in' (day 3-5), your baby gets colostrum — small amounts of incredibly nutrient-dense liquid. A few milliliters per feed is normal and sufficient in those early days. You don't need to supplement with formula unless your pediatrician specifically recommends it.
Almost all newborns lose 5-10% of their birth weight in the first few days. This is normal and expected — they're shedding extra fluid from birth. What matters is that they start gaining by day 4-5 and are back to birth weight by 10-14 days.
If you're seeing most of these, your baby is eating enough — even if it feels like they're never satisfied during a growth spurt.
These signs warrant a call to your pediatrician. They don't necessarily mean something is seriously wrong, but they need professional assessment.
The newborn period is intense. Your baby is growing faster than they ever will again, and growth spurts are the mechanism that makes it happen. They're exhausting, they disrupt whatever fragile routine you've established, and they can make you question whether you're doing everything right.
You are. Feed on demand, track the basics if it helps you feel grounded, and remember that every growth spurt ends. Your baby will be bigger on the other side, your milk supply will catch up, and things will settle — until the next one. But even the next one ends too.
This guide is for informational purposes only and is not a substitute for professional medical advice. If you have concerns about your baby's growth, please consult your pediatrician.
