Month 4
Key points
- Babies become increasingly social and aware at this stage.
- Your baby’s usual milk is still the sole source of food and nutrition for babies at four months.
- Physically, your baby moves with more intention as their limbs get stronger.
Congratulations! You and your baby have hit the magical milestone of four months! Perhaps you’re enjoying this stage of parenthood as your little one’s personality starts to shine through and their physical and cognitive changes continue at quite a pace. It’s good to remember that life is slightly different for everyone at the various stages of parenting.
After 16 busy weeks, life before children might feel like a distant memory as you can’t imagine not being a parent. Your baby may be sleeping around 10 to 18 hours in a 24-hour period and having up to three naps a day – and you’re all managing the ‘leaps’ as best you can![i]
Nutrition at Four Months
At about four months, your baby may have doubled their birth weight and they continue to rely on breast milk (or infant formula) as their sole source of food and nutrition. The clever composition of breast milk changes to provide everything your baby needs, from quenching their thirst to supplying protein for growth and muscle development. [ii]
The fats in breast milk provide an excellent source of essential fatty acids, which are vital for brain development, cognitive function and the nervous system. The essential fatty acid Omega-3 DHA, in particular, plays an important role in brain and retina (eye) development. The fats in breast milk also provide approximately 50% of your baby’s daily energy needs and help keep them feeling full.
Just as it does for adults, in babies, protein is used for muscle and bone growth and development, which makes it an important component in breast milk. The level of protein in your milk will have decreased slightly since you started feeding, although it still provides whey and casein proteins that are easy to digest while also building muscles, organs and tissues.
What is Breast Milk Made Up Of?
- Breast milk provides the ideal balance of fats, proteins, carbohydrates and vitamins, which adapts as your baby’s needs change.
- Whey and casein are the proteins present in breast milk, in a ratio of about 80% whey to 20% casein in the first few weeks, moving to 50:50 at about six months of lactation.
- The protein levels in breast milk remain stable regardless of a breastfeeding mum’s protein intake.
- Prebiotics like Human Milk Oligosaccharides are present to help establish a healthy gut microbiome, and aid in digestion and overall health, including reducing the risk of allergies and improving the body’s ability to absorb nutrients.
- Antibodies, white blood cells and other bioactive components help protect against infections and strengthen your baby’s immune system.
How Protein in Breast Milk Changes Over Time
In the early weeks of breastfeeding, breast milk contains a high level of protein at about 1.1g/100mL of breast milk to support your newborn’s rapid growth. During the later stages, when their growth rate slows, the level of protein is reduced to about 0.9g/100mL to ensure they aren’t getting more than they need. These changes allow for healthy growth patterns by providing the perfect amount to support growth and development.
Whey protein is the most abundant protein in breast milk as it is easier for baby to digest, as well as providing important immune benefits. Casein is a protein that helps create a curd in the stomach that slows digestion and keeps baby fuller for longer. The proteins in the breast milk at four months continue to help with growth and development, enzyme production and hormone regulation. As you breastfeed, the ratio of whey to casein adapts to your baby’s needs. In the first few weeks, the whey to casein ratio is 80:20. By about week three, it’s about 60% whey and 40% casein and levels out at 50:50 in later lactation (around six months).
Weight and Height of Four-Month-Old Baby
If you look back four months, it can be hard to believe that your newborn bundle is now around double the size (based on full-term babies). There are lots of variables when it comes to how a baby grows, including the size and ethnicities of their parents – so keep in mind that weight and height guides are averages. Your baby may…
- Weigh about 6.4 kg (girl) or about 7 kg (boy)
- Be about 62.1 cm tall (girl) or about 63.9 cm tall (boy)
Baby’s Visual & Cognitive Milestones at Four Months
As you can probably see from your baby’s interaction with you and the world around them, there are some important visual and sensory milestones at four months. Their eyes can better track objects or people as they move around them, they may recognise someone when they enter a room and they may be attracted to bright colours – particularly primary colours – and patterns.
These developments work with others including improved memory (recognising faces, toys and patterns, for example), cause and effect (‘if I shake this, it will make a noise’) and increased attention span (listening and looking at you as you talk to them).
By about four months, your baby may also:
- recognise and respond to certain familiar sounds,
- be able to focus on objects that are further away, up to about one metre,
- babble regularly, using rhythms and inflections,
- be more interested in faces as their sharpening vision makes it easier for them to distinguish features, and
- have increased depth perception and be able to gauge how far away something is, like a toy they are reaching for.
Playtime becomes increasingly fun for all of you as your little one is more interactive than ever. Try hiding your face behind a book or a toy behind your back, and playing peekaboo to see their reaction.
Motor Development at Month Four
At four months of age, your baby’s muscle strength, motor coordination and overall physical control improve. Some of the main motor milestones typically include better head control and neck stability when sitting supported or during tummy time. Many of these achievements connect as head stability and tummy time in turn support rolling over, pushing up to crawl and sitting up.
Your baby might enjoy ‘standing’ when you hold them, putting their feet on a flat surface (or your lap) and bouncing up and down. This is all part of them strengthening their muscles and gaining more control over their body. At four months old, your baby might also:
- roll over – usually from their tummy to their back in the first instance,
- grasp and hold objects with better hand–eye coordination, and
- hold their chest up and push onto their hands during tummy time.
Social Development of Your Four-Month-Old
As your little one’s eyesight improves so does their memory and facial recognition. You may find they get excited when they hear a familiar voice or see a familiar person, that they laugh at silly faces and enjoy listening to stories/your voice as their attention span increases.
You may also notice that they:
- start to show their likes and dislikes, by turning away when offered something, for example, and
- have developed different cries that show if they’re tired, hungry or uncomfortable.
Don’t forget!
It’s important to remember that every baby develops at their own rate. Regular checkups with your health nurse or GP will be able to ensure your baby is on track – but always get in touch with them sooner if you have any concerns. For extra resources, you can also head to Karitane or Tresillian online.
What’s next?
The period from 16 to 20 weeks features many exciting milestones that may include regularly rolling over, squealing with delight and taking an interest in solid foods. Read on to learn about your baby’s development milestones and nutritional needs in month five.
We are here to support you on your journey
Making decisions around infant feeding can be challenging and we hope we can help you through this journey.
We want to make sure you are informed and supported.
Before and during breastfeeding, it is important to maintain a healthy and balanced diet and it is recommended to exclusively breastfeed for the first six months of age, as it provides ideal nutrition and promotes a healthy start in life.
We understand breastfeeding is not always possible, and when necessary, infant formula is the most suitable alternative to breastfeeding. Introducing partial bottle-feeding may interfere with breastfeeding your infant and it can be hard to reverse. Other considerations include the social and financial implications of feeding infant formula. We want to make sure your baby is as safe as possible, so please refer to the preparation and storage instructions for safe use of infant formula and be aware that any unnecessary or improper use of infant formula may cause health hazards for your baby.
Your choice, our support, always. With love.
If you require further information, consult your healthcare professional or learn more about the benefits of breast milk.
[i] https://www.betterhealth.vic.gov.au/health/healthyliving/typical-sleep-behaviour-nb-3-6-months
[ii] https://www.tresillian.org.au/baby/development/baby-weight/
