Baby development by age

First two weeks

Survival mode. Feed, sleep, diapers, repeat. You are doing better than you think.

What's happening

• Sees best 8–12 inches away, exactly the distance to your face while feeding.
• Recognises your voice and smell from day one. Startles at loud sounds.
• Loses 5–7% of birth weight in the first days, back to birth weight by day 10–14.
• Sleeps 14–17 hours a day in 2–4 hour stretches with no day/night pattern yet.
• Reflexes rule: rooting, sucking, grasping, startle (Moro).

Habits forming now

• Nothing you do now creates bad habits. You cannot spoil a newborn; responding fast builds trust.
• Day/night confusion is normal. Bright, noisy days and dark, boring nights start teaching the difference.

What to do

• Skin-to-skin as much as you both like. It steadies breathing, temperature and feeding.
• Talk, sing and narrate what you're doing. Language learning starts now.
• Take shifts at night if you can (one parent 9pm–2am, the other 2am–7am) so each gets a real block of sleep.
• Accept help. Let visitors bring food and hold the baby while you nap or shower.
• Umbilical stump: keep dry, fold diaper below it, falls off in 1–3 weeks.

Feeding and sleep

• Feed on demand, at least 8–12 times in 24 hours. Wake baby if 3 hours pass without a feed until weight is regained.
• Day 1 feeds are 5–7 mL; by day 7 around 45–60 mL (1.5–2 oz). Their stomach is tiny.
• Expect at least 6 wet diapers a day from day 5 and 3–4 yellow seedy stools (breastfed) or firmer tan stools (formula).
• Always on the back, on a firm flat surface, nothing else in the crib or bassinet.

Talk to the doctor if

• Fever of 100.4 °F (38 °C) or higher rectally: call the doctor immediately, day or night.
• Yellow skin or eyes spreading down the body (jaundice), or extreme sleepiness / refusing feeds.
• Fewer than 6 wet diapers a day after day 5, or dark urine.
• Breathing that looks laboured, grunting, or a blue tint around the lips.

2–6 weeks

Crying peaks, growth spurts hit, and the first real smile is coming.

What's happening

• Crying increases and peaks around 6–8 weeks (the PURPLE crying period). Up to 2–3 hours a day can be normal.
• Growth spurts around 2–3 weeks and 6 weeks: suddenly hungry all the time for 2–3 days.
• Starts to follow your face with their eyes and briefly lift the head during tummy time.
• First social smile shows up around 6 weeks. Worth the wait.

Habits forming now

• A short, repeatable bedtime routine (feed, change, swaddle, song, dark room) can start at 6–8 weeks. It becomes their cue for sleep.
• Practise putting baby down drowsy but awake sometimes. No pressure: it only works some of the time at this age.

What to do

• Tummy time 2–3 times a day for a few minutes, on your chest counts. Builds neck strength and prevents flat spots.
• For crying: the 5 S's — Swaddle, Side/stomach hold (awake only), Shush, Swing, Suck. Try them in order.
• If the crying gets to you, put baby safely in the crib and step out for a few minutes. Never shake a baby.
• Check in on each other. Mood swings are expected; sadness or anxiety that lasts more than 2 weeks is not just tiredness. Either parent can get postpartum depression.

Feeding and sleep

• Formula: about 2.5 oz per pound per day (150–200 mL/kg), usually 2–4 oz every 3–4 hours. Breastfed: 8–12 feeds, on demand.
• Cluster feeding in the evening is normal and is not a sign of low milk.
• Total sleep 14–17 hours. The longest stretch slowly grows to 4–5 hours.
• Stop swaddling at the first sign of trying to roll, usually around 8 weeks.

Talk to the doctor if

• Projectile vomiting after most feeds (pyloric stenosis), green vomit, or blood in stool.
• No smile or eye contact by 8 weeks, or not reacting to loud sounds.
• A soft spot that bulges when calm and upright, or a very sunken one.

6–12 weeks

Smiles, coos, and longer nights. The fog starts to lift.

What's happening

• By 2 months: smiles when you talk to them, calms when picked up, looks at your face, makes sounds other than crying, holds head up on tummy.
• Starts cooing (ooo, aah) and taking turns making sounds with you.
• The body starts making melatonin around 8–12 weeks, so a real day/night rhythm begins to form.
• Crying starts to ease after the 6–8 week peak.

Habits forming now

• Sleep associations form now: however baby falls asleep at bedtime is how they will expect to fall back asleep at 2am. Rocking to sleep is fine; just know it becomes the expectation.
• A consistent bedtime between 7 and 8 pm and a dark room make the longest stretch land at night.
• Wake windows of about 60–90 minutes; overtired babies fight sleep harder.

What to do

• Serve and return: when baby coos, answer. Pause, let them reply. This back-and-forth builds the brain more than any toy.
• Read to them daily, even the newspaper. It is the rhythm of your voice that matters.
• Get out of the house every day. A walk resets both of you.
• 2-month checkup: first big round of vaccines (DTaP, IPV, Hib, PCV, rotavirus, HepB). A fussy day after is normal.

Feeding and sleep

• Typical bottle 4–5 oz (120–150 mL) every 3–4 hours, 24–32 oz a day. Breastfed intake stays around 25 oz a day from here until solids.
• Longest night stretch of 5–6 hours is common by 12 weeks, but many healthy babies still wake every 3 hours.
• Vitamin D 400 IU daily for breastfed babies (formula already has it).

Talk to the doctor if

• Not smiling by 3 months, not tracking a moving object, or not lifting the head at all during tummy time.
• A consistent head tilt or flat spot on one side (ask about torticollis / plagiocephaly).

3–4 months

Laughing, grabbing, and the famous 4-month sleep change.

What's happening

• By 4 months: chuckles, makes sounds to get your attention, holds head steady, brings hands to mouth, pushes up on forearms, swats at toys, opens mouth when they see the bottle or breast.
• Discovers their hands. Everything goes in the mouth (that is exploring, not teething yet).
• Around 4 months sleep permanently reorganises into adult-like cycles, so baby now wakes briefly between cycles. This is the '4-month sleep regression'.
• Some babies roll front-to-back as early as 3–4 months.

Habits forming now

• Now sleep habits really stick. If you want baby to fall asleep without being held or fed, this is the window to start practising gently.
• Routines help: wake, feed, play, nap. A predictable rhythm (not a strict schedule) settles most babies.
• 3–4 naps a day, wake windows 1.5–2.5 hours.

What to do

• Offer toys to grasp: rattles, soft rings, crinkly books.
• Sing, make faces, play peek-a-boo. Laughter is their new favourite thing.
• 4-month checkup: second round of vaccines.
• Once they can roll, stop swaddling completely and move to a sleep sack.

Feeding and sleep

• Bottles of 5–6 oz, 24–32 oz a day. Feeds may become quicker and more distracted. Feed in a quiet room.
• Hold off on solids and cereal in the bottle. The AAP recommends waiting until around 6 months.
• Total sleep 12–16 hours. Many babies can go 6–8 hours at night now; some can't yet. Both are normal.

Talk to the doctor if

• Doesn't watch things move, doesn't smile at people, can't hold head steady, doesn't bring hands to mouth, doesn't push down with legs when feet are on a hard surface.

4–6 months

Rolling, sitting with help, and getting ready for real food.

What's happening

• By 6 months: knows familiar people, likes the mirror, laughs, blows raspberries, squeals, rolls tummy to back, pushes up on straight arms, leans on hands while sitting, reaches for toys.
• Babbling begins: ba, ma, da strings with no meaning yet.
• Teething can start (drool, chewing, mild fussiness). First tooth usually 6–10 months.
• Signs of readiness for solids: sits with support, good head control, watches you eat, has lost the tongue-thrust reflex.

Habits forming now

• Night feeds may naturally drop to 0–1 for formula-fed babies; breastfed babies often keep 1–2. Either is fine if weight gain is good.
• Falling asleep independently at bedtime becomes possible for most babies now. Gentle methods work; consistency matters more than the method.
• Stranger awareness starts creeping in toward 6 months.

What to do

• Start solids around 6 months (not before 4): iron-rich first foods like iron-fortified cereal, pureed meat, beans. One new food every 2–3 days.
• Introduce peanut, egg and other allergens early and regularly once solids start (thinned peanut butter, well-cooked egg). Early introduction lowers allergy risk. Ask your doctor first if baby has severe eczema.
• Baby-proof now, before they are mobile: outlet covers, cords, small objects, furniture anchors.
• 6-month checkup: third round of vaccines, plus flu shot in season.

Feeding and sleep

• Milk is still the main food: 24–32 oz a day. Solids are for practice, not calories, at first.
• Offer water in a small cup with meals once solids start (a few sips is plenty).
• 3 naps a day, wake windows 2–3 hours, 10–12 hours at night.

Talk to the doctor if

• Doesn't try to get things in reach, shows no affection, doesn't respond to sounds around them, doesn't make vowel sounds, doesn't roll in either direction, seems very stiff or very floppy.

6–9 months

Sitting, scooting, separation anxiety, and a personality that is impossible to miss.

What's happening

• By 9 months: sits without support, gets to sitting by themselves, passes things hand to hand, rakes food with fingers, bangs two things together, looks when you call their name, is shy or clingy with strangers, plays peek-a-boo, says mamamama / babababa.
• Object permanence arrives around 8 months: they now know you exist when you leave the room, hence separation anxiety and the sudden protest at bedtime.
• Crawling, scooting or bottom-shuffling typically 7–10 months. Some skip crawling entirely.
• Pincer grasp (thumb and finger) develops toward 9 months.

Habits forming now

• Separation anxiety can undo good sleep for a few weeks. Keep the routine, keep goodbyes short and cheerful, and it passes.
• Naps consolidate from 3 to 2 (morning and early afternoon) around 7–9 months.
• A lovey (small blanket or soft toy) can become a comfort object now, but keep it out of the crib until 12 months.

What to do

• Play games with rules: peek-a-boo, pat-a-cake, rolling a ball. Name everything.
• Let them self-feed soft finger foods (banana, avocado, well-cooked pasta, toast strips). Mess is learning.
• Read books with flaps and textures. Point to pictures and name them.
• 9-month checkup: developmental screening, usually no vaccines unless catching up.

Feeding and sleep

• Move toward 3 meals a day plus milk. Milk drops to about 24–30 oz as solids grow.
• Practice with an open cup or straw cup: the goal is to wean bottles by 12–18 months.
• Avoid honey (until 12 months), choking hazards (whole grapes, nuts, hard raw veg, hot dogs), added salt and sugar.

Talk to the doctor if

• Doesn't bear weight on legs with support, doesn't sit with help, doesn't babble, doesn't respond to their name, doesn't look where you point, doesn't transfer toys between hands.

9–12 months

Pulling up, cruising, first words, and a little person with big opinions.

What's happening

• By 12 months: pulls up to stand, walks holding furniture, drinks from a cup you hold, picks things up between thumb and finger, waves bye-bye, calls a parent mama/dada, understands 'no', looks for hidden things, plays pat-a-cake.
• First words often around 12 months, but understanding is far ahead of speaking. They know dozens of words.
• Points to show you things. Pointing is a huge milestone for communication.
• First steps anywhere from 9 to 15 months. Late walkers are usually just cautious.

Habits forming now

• Testing limits starts. Consistent, calm 'no' plus redirection works better than anything else at this age.
• Sleep: 2 naps, 11–12 hours at night. Standing in the crib at bedtime is a phase; practise sitting down during the day.
• Screens: none before 18 months except video chat with family.

What to do

• Talk constantly, use real words not baby talk, and wait for a response. Repeat their attempts back correctly.
• Give safe choices ('red cup or blue cup?') to channel the growing independence.
• Push toys, stacking cups, containers to fill and dump, and lots of floor time.
• 12-month checkup: MMR, chickenpox, hepatitis A, plus Hib and PCV boosters. Iron and lead screening.

Feeding and sleep

• Three meals and 1–2 snacks; milk 16–24 oz. Whole cow's milk can replace formula after the first birthday (16–24 oz a day, not more).
• Ditch the bottle between 12 and 18 months. Cups at meals only; no bottle in bed (tooth decay).
• Brush the teeth twice a day with a rice-grain smear of fluoride toothpaste. First dentist visit by the first birthday.

Talk to the doctor if

• Doesn't crawl or scoot, can't stand with support, doesn't search for hidden objects, doesn't say single words, doesn't use gestures like waving or pointing, loses skills they once had.

12–18 months

Toddlerhood. Walking, tantrums, and a vocabulary explosion around the corner.

What's happening

• By 15 months: takes a few steps, tries 1–2 words besides mama/dada, follows simple directions with gestures, points to ask, copies other children, claps when excited, stacks two blocks, uses things the right way (phone, cup).
• By 18 months: walks without holding on, scribbles, drinks from a cup, feeds self with fingers, tries a spoon, climbs on and off a couch, says 3+ words, follows one-step directions without gestures, copies chores, points to show you things.
• Tantrums start because feelings are big and words are few. They peak between 18 months and 3 years.
• Molars come in; expect some rough nights.

Habits forming now

• Transition to one nap around 15–18 months (usually after lunch, 1.5–3 hours).
• Bedtime routine of 20–30 minutes: bath, teeth, books, song, bed. Same order every night.
• Toddlers thrive on predictable rhythm and clear, kind limits. Tell them what to do, not just what not to do.

What to do

• Name feelings for them: 'You're mad because the block fell.' It builds emotional vocabulary.
• Read every day, let them turn pages, ask 'where's the dog?'.
• Offer independence: let them try the spoon, carry a small bag, choose a shirt.
• 15-month and 18-month checkups: DTaP booster, hepatitis A, and autism screening (M-CHAT) at 18 months.

Feeding and sleep

• Appetite drops sharply as growth slows. One good meal a day is common; judge intake over a week, not a day.
• Milk 16–24 oz, water with meals, no juice needed.
• 11–14 hours of sleep a day including the nap.

Talk to the doctor if

• Doesn't point to show things, doesn't walk by 18 months, doesn't know what familiar things are for, doesn't copy others, doesn't gain new words, doesn't notice or mind when a caregiver leaves or returns, loses skills.

18–24 months

Two-word sentences, running, pretend play, and 'no' as a lifestyle.

What's happening

• By 24 months: says at least two words together ('more milk'), points to things in a book when asked, points to at least two body parts, uses gestures like blowing a kiss or nodding, kicks a ball, runs, walks up a few stairs, eats with a spoon, plays with more than one toy at a time, notices when others are upset.
• Vocabulary jumps from about 50 words to 200–300 by the second birthday.
• Pretend play appears: feeding a doll, talking on a toy phone.
• Parallel play: happy next to other kids, not really with them yet.

Habits forming now

• Some children show potty-training readiness (staying dry 2 hours, telling you about a wet diaper, interest in the toilet). Most are ready between 2 and 3. No rush.
• Keep the crib until they climb out or turn 3; a bed too early usually means a wandering toddler.
• Screen time, if any: under an hour a day of quality content, watched together.

What to do

• Expand what they say: 'Truck!' → 'Yes, a big red truck.'
• Give simple jobs: put the cup on the table, bring your shoes. They love helping.
• Outdoor time daily: running, climbing, digging. Big-muscle play helps sleep and mood.
• 24-month checkup: developmental and autism screening, possible hepatitis A dose 2.

Feeding and sleep

• Whole milk 16 oz is plenty; too much milk crowds out iron-rich food.
• Let them serve themselves from small portions; new foods can take 10–15 exposures before they are accepted.
• 11–14 hours of sleep. One nap, bedtime 7–8 pm.

Talk to the doctor if

• Doesn't use two-word phrases, doesn't know what to do with common things (brush, spoon), doesn't copy actions and words, doesn't follow simple instructions, doesn't walk steadily, loses skills.

🛏️ Safe sleep (AAP 2022)

• Back to sleep, every sleep, until their first birthday. Once they roll both ways on their own, you don't need to flip them back.
• Firm, flat surface with only a fitted sheet. No pillows, blankets, bumpers, positioners or stuffed toys. No inclined sleepers.
• Room-share (baby's own crib or bassinet in your room) ideally for the first 6 months. Don't bed-share, and never sleep with baby on a couch or armchair.
• A pacifier at sleep time lowers SIDS risk. Don't force it, and don't clip it to clothing in the crib.
• Keep the room comfortably cool, dress baby in one more layer than you'd wear, no hats indoors. Sweating or a hot chest means too warm.
• Swaddle only until the first sign of rolling (often ~8 weeks), then a sleep sack. Avoid weighted sleep sacks and blankets.
• Smoke-free home and car. Breastfeeding, if it works for you, also lowers SIDS risk.

🤱 Soothing a crying baby

Crying peaks around 6–8 weeks and eases by 3–4 months. It is communication, not a judgement of your parenting.

• Run the checklist: hungry, dirty, too hot/cold, tired, overstimulated, wants to be held, gas.
• The 5 S's (Karp): Swaddle snugly, Side or Stomach hold in your arms, Shush loudly near the ear, Swing with small fast jiggles (support the head), Suck on a pacifier or clean finger.
• Movement and white noise: a walk, a carrier, a bouncy chair, the dryer's hum, a fan.
• Dim the lights and lower the noise. Overtired, overstimulated babies cry harder.
• Try each thing for a few minutes before switching. Constant switching is more stimulation.
• If you feel yourself losing it: put baby in the crib on their back, close the door, take 10 minutes. Crying won't hurt them. Shaking can kill or cause permanent brain damage.
• Some evenings nothing works. Hold them, breathe, and know it passes.

🍼 Feeding cues & enough milk

• Early hunger cues: stirring, mouth opening, rooting, hands to mouth. Active: stretching, fussing, more movement. Late: crying, red face. Feed at early cues when you can; calm a crying baby first.
• Fullness: slows down, unlatches, turns away, relaxed open hands, falls asleep. Don't push the last ounce.
• Paced bottle feeding: baby upright, bottle horizontal, pauses every few sucks. Prevents overfeeding and helps breastfed babies accept a bottle.
• Enough milk? 6+ wet diapers a day after day 5, steady weight gain (5–7 oz a week in the first 4 months), content between most feeds.
• Breastfeeding: expect cluster feeds in the evening and during growth spurts (2–3 wks, 6 wks, 3 mo). Supply follows demand.
• Burp midway and after. Spit-up is normal if baby is happy and gaining; forceful vomiting is not.
• Formula: follow the tin exactly (water first, then powder), use within 1 hour once baby has drunk from the bottle, refrigerated prepared formula within 24 hours.
• Breast milk storage: room temp 4 hours, fridge 4 days, freezer 6 months (12 max). Never microwave.

💩 What's normal in a diaper

• Days 1–2: black, tarry meconium. Days 3–4: green-brown transition. Day 5+: yellow seedy (breastfed) or tan/yellow paste (formula).
• Breastfed babies may poop after every feed or, after 6 weeks, only every few days. Both are fine if it's soft.
• Green stools are usually harmless (foremilk/hindmilk, iron, a virus). Call for: white/chalky, black after the first week, or red/bloody stools.
• Constipation = hard pellets and straining with pain, not just going a few days. Formula babies are firmer; talk to your doctor before changing formula.
• Diarrhoea: watery, more frequent than usual, often with mucus. Watch for dehydration (fewer wet diapers, dry mouth, no tears, sunken soft spot).
• Diaper rash: change often, air time, thick barrier cream (zinc oxide) with every change. Bright red rash with satellite spots = likely yeast, ask the doctor.
• Pee: pale yellow is right. Orange-pink 'brick dust' crystals in the first days are normal; after day 4 they mean baby needs more milk.

🩺 Checkups & vaccines (US schedule)

Well visits: 3–5 days, then 1, 2, 4, 6, 9, 12, 15, 18, 24 months. Each visit weighs and measures, so log those numbers in Growth.

• Birth: hepatitis B (dose 1). RSV antibody (nirsevimab) in RSV season if mom didn't get the RSV vaccine in pregnancy.
• 2 months: DTaP, IPV (polio), Hib, PCV (pneumococcal), rotavirus, hepatitis B.
• 4 months: DTaP, IPV, Hib, PCV, rotavirus.
• 6 months: DTaP, PCV, rotavirus (some brands), hepatitis B, IPV (6–18 mo). Flu vaccine each season from 6 months (two doses the first year); COVID vaccine per current guidance.
• 12 months: MMR, varicella (chickenpox), hepatitis A, Hib and PCV boosters.
• 15 months: DTaP booster. 18 months: hepatitis A dose 2.
• After shots: fussiness, mild fever, sore leg for a day or two is normal. Ask before giving acetaminophen; never aspirin.
• Bring your questions written down. The app's History page shows patterns the doctor will ask about (feeds, sleep, diapers).

🚨 When to call the doctor

Call the same day, or go to the ER, for any of these. Trust your gut: you know this baby better than anyone.

• Any fever ≥100.4 °F (38 °C) rectal in a baby under 3 months. This is an emergency, even if they seem fine.
• Trouble breathing: fast breathing, flaring nostrils, ribs pulling in, grunting, blue or gray lips.
• Very sleepy or floppy, hard to wake for feeds, or inconsolable high-pitched crying for hours.
• Signs of dehydration: fewer than 6 wet diapers a day (after day 5), no wet diaper in 8 hours, dry mouth, no tears, sunken soft spot.
• Repeated forceful vomiting, green (bile) vomit, blood in vomit or stool.
• Refusing two feeds in a row, or a sudden drop in feeding.
• Worsening jaundice (yellow spreading to belly and legs, or lasting past 2 weeks).
• A rash with fever, or a rash that doesn't fade when you press a glass on it.
• Any fall from height, hit to the head, or if you're worried and can't say why.

❤️ Being a good parent (and staying sane)

• Responsive is the whole job: notice what baby needs and answer, most of the time. 'Good enough' is what builds secure attachment; perfect doesn't exist.
• Talk, read, sing, and play face to face every day. Thirty minutes of real back-and-forth beats any educational product.
• Sleep is a health need, not a luxury. Split nights into shifts, nap when baby naps at least once a day, and say yes when someone offers to take a feed.
• Postpartum depression and anxiety hit about 1 in 7 mothers and 1 in 10 fathers, often in the first year. Persistent sadness, rage, dread, intrusive thoughts, or not being able to sleep when the baby sleeps are reasons to call your doctor, not signs of weakness.
• Argue about the load out loud and early. Write down who does what (nights, bottles, laundry, appointments) and revisit it every couple of weeks.
• Protect one small thing for each of you every week: a run, a coffee alone, a show. Parenting is a marathon.
• Baby-proof before mobility, not after: anchor furniture, cover outlets, lock cabinets, lower the crib mattress when they sit, water heater at 120 °F, no small objects within reach.
• Skip the comparison. Every baby has their own timeline for teeth, rolling, words and sleep. The milestone lists above are 'by this age most do', not deadlines.
• Ask for help specifically: 'Could you bring dinner Tuesday?' works far better than 'let us know if you need anything'.

🧸 Tummy time & play by age

• Tummy time from day one: on your chest, across your lap, on a mat. Aim for 15–30 minutes total a day by 7 weeks, building to an hour by 3–4 months.
• 0–3 months: high-contrast cards, your face, a play gym with dangling toys, gentle songs with movement.
• 3–6 months: rattles and rings to grasp, unbreakable mirror, textured cloth books, supported sitting on your lap.
• 6–9 months: stacking cups, balls that roll, boxes to bang, peek-a-boo, water play in the bath.
• 9–12 months: push toys, shape sorters, board books with flaps, containers to fill and dump, cruising along furniture.
• 12–24 months: balls to kick, chunky crayons, simple puzzles, pretend kitchen, blocks, climbing at the playground, and lots of narrated everyday chores.
• Limit time in containers (bouncers, swings, car seats) to 15–20 minutes at a stretch when awake. Floor time is where motor skills grow.