Watching your baby grow inside you during the different stages of pregnancy was NOTHING compared to what you get to witness during their first year of life. Seriously.
We talk a lot about how hard motherhood is, because, um, it’s really hard. But this stuff is what makes it oh so worth it. You’re gonna want plenty of space on your iPhone to capture photos and videos of the magic.
In this guide to your baby’s growth and development, we’ll touch on what to expect during the first weeks and months of their life. But first, a brief disclaimer:
All babies grow and develop at different rates. They’re humans, not robots. They do their own thang. So don’t freak out if your child isn’t hitting every baby development milestone on the list in the right week or month. But if you ever ARE concerned about your baby’s development, it can’t hurt to mention it to your paediatrician.
That said, let’s look at baby development stages and growth expectations in their first year.
No matter what pregnancy complications you encountered, and what happened during labour to f*ck up your birth plan (it happens!), your baby has arrived. Whether they’re bigger or smaller than average isn’t a huge deal – what matters is that they grow consistently over time. So don’t compare your baby to others. But DO know that it’s completely normal for babies to lose between five and 10 percent of their birth weight in Week 1.
This first week is all about learning to live outside the womb. Pretty freaky stuff. Your newborn’s key priorities are breathing, feeding, sleeping, and pooping (lots of pooping).
10–14 days after delivery, your baby will typically be back to their birth weight.
Your two-week-old will be sleeping up to 18 hours a day. It’s hard to manage impressive baby development milestones around that sleeping schedule, but if they’re crying, feeding and pooping lots, it’s a good sign.
In the first few weeks, newborns typically gain around ⅔ of an ounce (20–30g) PER DAY, and grow 1.5–2 inches (4.5–5cm). So no, you’re not just imagining that your baby looks bigger every day. They actually are.
As your little one’s muscle strength grows, they may start to be able to lift their head for a few seconds or even turn their head side to side.
By now, you may have paid a few visits to your doctor or maternal child health nurse for growth checks, so you’ll have an idea of where your bub is tracking against the standardised baby growth chart. While wellbeing checks may vary state-to-state, you’ll generally have a few in your first few weeks. Remember – some babies are bigger, some are smaller, the main thing your doctor will check for is that they’re growing consistently.
By the end of their first month, your baby’s hearing should be fully developed. They may turn towards familiar sounds (your incredible operatic rendition of “Twinkle Twinkle Little Star”), and even make sweet, little cooing sounds themselves.
Other four-week-old baby development milestones include natural reflexes like clutching, holding their head up, making fists, and thrashing their little limbs around like tiny psychotic orchestra conductors.
The median length of a five-week-old according to the official World Health Organization baby girl growth chart is 54.2cm (21.3 inches), while the baby boy growth chart lists 55.3cm (21.7 inches). So your baby is likely to have grown 5cm in the past five weeks! They may have even gone up a size or two already.
By Week 5, they’re likely to be able to hold small objects when placed in their hand, and may start holding their head up for a bit longer. They might even start using actions to communicate, like making noises to get your attention or wiggling when you come near (translation: “pick me UP, my milkmaid!”).
A lot of babies experience a little growth spurt at around the six-week mark. It’s normal for your baby to have faster and slower periods of growth, so don’t worry if they don’t grow a whole lot one week – they’ll probably make up for it the next!
By now, your baby will start to get bored and need stimulation to stay content. They’ll also develop their own little ways of soothing themselves when they’re upset. Your bub might suck on their fist, for example. They might even learn to SMILE at you this week! Mama, get your camera on standby.
The baby boy growth chart lists seven-week-olds at 57.1cm (22.5 inches) on average, while the baby girl growth chart lists them as 55.8cm (almost 22 inches).
Just remember, your little one will be cruising along in their own baby growth percentile. So if they’re in the 15th percentile they’ll be smaller than the average, and if they’re in the 85th percentile they’ll be bigger. All’s swell as long as they’re healthy and following an upward trend in growth.
Your seven-week-old will start to develop an obsession with batting at hanging objects (beware dangly earrings). This is an important addition for tummy time as well, as your baby needs to build strength in their neck and arms.
Up until six months of age, most babies grow about 1.5–2.5cm (1/2 to 1 inches) a month, and gain about 140–200 grams (5 to 7 ounces) a week. While your arms might not appreciate the extra weight, at around 2–3 months your baby will start to develop that classic, adorable infant chubbiness.
Squeeze those chubba cheeks – it’s your motherly rite of passage.
By two-months old your baby will be able to recognise familiar faces, make gurgling noises (the foundations of learning to speak), and move their body with more purposeful movements. By three months, they’ll be able to sit up on your lap and support their own head more (not entirely), focus their eyes better, and lift their torso up with their arms during tummy time.
By five months old, your baby will probably have doubled their birth weight. As they prepare to start eating solid foods, get ready for their growth to really take off over the coming months!
Your little one will pick up lots of new skills over these few months. At your scheduled baby development checkups, your healthcare practitioner will look out for key baby development milestones.
At four months your baby may be able to:
At six months, they may be able to:
Hell, they may even start crawling at six months. Time to baby-proof your house.
Most babies start cutting teeth around six months of age. It could happen earlier or later, though.
From ages six to 12 months, baby growth tends to slow down a little. They might grow about 1cm (3/8 inch) a month and gain 85-140 grams (about three to five ounces) a week. And they’re likely to triple their birth weight by their first birthday!
Expect your little one to hit some serious baby development milestones during this period. As they get more agency over their bodies and start to move around more, they’ll keep you on your toes for sure!
By nine months, they may have learned to:
At 10 months, the average baby girl will be about 71.5cm (28 inches) in length, and weigh 8.5kg (18.5 pounds). A baby boy will be about 73.3cm (29 inches) long, and weigh 9.2kg (20 pounds).
We’ve said it a billion times already but we’ll say it again: we’re just talking averages here. Your paediatrician will measure your child against their baby development chart to determine if they’re on track for their unique baby growth percentile.
By the time they reach 12 months, they’re expected to have tripled their birth weight and be 50% longer than they were when they slid out of your uterus. They might have anywhere between one and eight teeth by now, too.
During the last few months of your baby’s first year, they’ll be developing in leaps and bounds. But we hope for your sake they’re not actually leaping and bounding yet. Some clumsy walking or crawling is hassle enough, thank you.
By 12 months, babies are measured against developmental milestones such as:
At one year old, your doctor will again plot your child’s measurements on a standardised baby growth chart to ensure they’re physically developing in the right pattern. Ensuring they’re eating enough and getting a good level of interaction and stimulation is key to nailing this growth and development thing.
So, now what? Is your kid a toddler? Do you get some kind of medal? Is there an initiation ceremony?
Making it through the first year is a huge achievement. We know it’s not exactly easy, but holy hell can it be amazing at times. (The first GIGGLE!)
If you thought the first year was fun, just WAIT for their second year. As your child continues to develop, they’ll pick up more independence, language skills, physical ability and amazing, amazing personality.
It’s so much fun. It’s also super tough work. But you’re up to the task. If you’ve made it this far, you’re doing great! Learn more and connect with other mums on the same wild ride as you by downloading Mumli today.
MedLine Plus, Normal growth and development
Verywell Family, Welcome to Your Baby’s First Year
Raising Children Network, About baby development and developmental milestones
Centers for Disease and Control Prevention, CDC’s Developmental Milestones
Word Health Organization, Child growth standards
The American Academy of Pediatrics, Starting Solid Foods