4 month old baby: Development, growth and milestones

four month old baby

by Stephanie Spencer |
Updated on

Medically reviewed by Dr Alexis Missick General Practitioner with over 10 years experience working in the NHS.

It’s hard to believe that your little one is now four months old, they’re starting to roll, hold up their own head and are well on their way to lots of exciting baby milestones like crawling and weaning.

Around 16 weeks is also the age your baby could be starting teething, and may experience a growth spurt. Here’s everything you need to know about this month of your baby’s development.

How much should a 4 month old baby sleep?

4 month baby sleep

Around four months old your baby’s sleep pattern will start to mature, most babies this age should sleep 8–16 hours per 24 hour period, which includes a longer stretch of 11-12 hours at night and at 3-4 naps during the day lasting 1-2 hours. "Shorter sleep times at night broken by periods longer than needed for a feed may indicate a growth spurt or other concerns depending on if there are any additional complaints." Says Dr Missick.

To optimise how much sleep your baby should have at this age, a good rule of thumb to stick to is that no nap should go longer than 2 hours, and wake windows should be around 90 to 120 minutes.

4 month old baby cognitive development

By now your baby will be showing increasing coordination between their hands and eye. They are able to recognise familiar faces, respond to affection, smile, and might even laugh. "At 4 months babies look at their hands with interest; the movement, shape, sensation." Says Dr Missick. "They also open their mouths if hungry when they see bottles or breasts in front of them. Parents can help by following cues." She adds.

They'll begin to develop their talking skills, raising and lowering the pitch of their babbling as if in conversation. You can encourage your baby's talking skills by chatting to them, Libby Hill, a speech and language therapist says, "Engaging with your baby from birth has an invaluable impact on his speech development. Babies love to listen to your voice, so talk, sing and coo, making eye contact as you go."

Here are a few activities you can try to encourage your baby's speech development:

• Talk in a sing-song voice

• Hold your baby close and look at them while talking

• Chat about what you are doing

• Sing

• Repeat the sounds your baby makes back to them

Remember, it doesn't matter what you talk about, and besides they'll love the attention! With your encouragement they may be saying their first words by five months old.

4 month old baby physical development

4 month old baby play

As your baby reaches four months and beyond, you'll find they get a lot more active.

"At 4 months we should notice improved head control where they hold their head steady without support." Says Dr Missick. "They should be able to bring their hands to their mouth, hold a toy when placed in their hand, attempt to get a toy (by swinging their arm at it) and begin to push up on their arms or elbow during tummy time."

Babies typically begin rolling over from their back and on to their front any time between four and five months). They may be reaching and touching their feet and might also push down on their legs when their feet are on a hard surface – clear indicators that they’re preparing themselves for crawling and walking.

"Parents can help by giving tummy time and by playing games such as giving them colourful, attractive, or noisy toys that they can try to reach for a hold." Adds Dr Missick.

4 month old activity ideas, play and development

From how to encourage rolling and sitting up, using tummy time and lap rhymes to strengthen their core, to reading stories and reaching out to grab and hold objects, there are lots of fun ways to encourage your baby's development at this age.

"By putting objects near to your baby when they’re on their tummy or on their back, you will be able to encourage them to not only reach out and grab those objects but also pick them up and bring them closer to themselves," says Sophie Pickles, infant and early childhood development specialist and mum of three. "You can also help them perfect that grabbing reflex by putting a toy in their hand for them to hold."

One of the best things to do at this age is to put your baby on their tummy in front of a mirror. "They will really enjoy looking at their reflection," explains Sophie, "although they won’t actually know its them! You can also get down on the floor with them and look into the mirror so they can see your face reflected back at them, you’re guaranteed to get lots of happy smiles!”

4 month old baby growth

By four months your baby will have doubled their birth weight. The average weight for a 4-month-old baby is 14.2 pounds for girls and 15.4 pounds for boys; the average length (aka height) is 24.4 inches for girls and 25.2 inches for boys. The 3 month or 4 month growth spurt can come on fast, is likely to be the biggest of the first year, and will cause your baby to be cranky, sleepy, and hungry, just like the first couple.

How much should baby be feeding at 4 months?

baby feeding 4 months

Breastmilk is still the only food your baby needs at this stage. "At 4 months, babies usually take 4-6 ounces every 3-4 hours." Says Dr Missick. You may also notice them teething at four months in preparation for solid foods. The most common signs of teething are drooling, flushed cheeks and red gums, a temperature, gnawing and chewing on things more, you may also notice them crying or rubbing their ear.

At this stage you can expect baby to have up to 10 nappy changes a day.

4 month old baby health

Teething: While teething can begin as early as 3 months, most likely you'll see the first tooth start pushing through your baby's gum line when your little one is between 4 and 7 months old. The first teeth to appear usually are the two bottom front teeth, also known as the central incisors. To soothe any discomfort this causes your baby, try gently rubbing or massaging the gums with one of your fingers. Teething rings are helpful, too, but they should be made of firm rubber.

When these new teeth appear it’s time to start brushing! Simply brush their teeth with a soft child’s toothbrush when you first start seeing her teeth. To prevent cavities, never let your baby fall asleep with a bottle, either at nap time or at night.

Colds: Babies are especially likely to get the common cold, in part because they're often around older children. At 4 months there's normally no need to go to the doctor when your little one gets the sniffles, as is recommended with younger babies. If your baby has a cold with no complications, it should resolve within 10 to 14 days. However, if their symptoms don't improve or if they worsen, visit your GP.

Vaccinations: At 4 months, babies are given their rotavirus vaccines. "Rotavirus vaccines protect against the virus which is responsible for vomiting and diarrhoea related illnesses at these ages" says Dr Missick. Baby is also coming up for the third dose of the 6-in-1 vaccine (diphtheria, tetanus, pertussis (whooping cough), polio, Haemophilus influenzae type b (Hib) and pneumococcal disease), so remember to make an appointment with your GP.

Things to think about at 4 months

Teething and breastfeeding: Nipple biting is common when babies get new teeth, but it only happens because your baby needs comfort as their gums hurt. If you’ve been struggling with breastfeeding or are finding the teething stage a hurdle to nursing, the NHS has a national breastfeeding support helpline.

Tummy time: If you haven’t started tummy time already, give it a go. It’s wonderful for your child’s physical development and will help them work out how to use their muscles properly to get them closer to the walking milestone.

Your own mental health: Dr Missick says now is a great time to start prioritising your mental health if you feel you're struggling. "At this stage, support for mum is always helpful as a means of an outlet to talk to  and unburden themselves but also for respite as the growth spurts and irritability caused by colic. Challenges with wake periods at night and teething experienced at these stages can be emotionally taxing on mothers."

5 tummy time tips

Tummy time baby

Parenting expert Fi Star-Stone says “Tummy time is important for your little ones development to strengthen muscles, improve coordination and help them to eventually crawl. You can start from birth with just two minutes a day, gradually working up to twenty minutes per day by the time they are 6 months old. It's a lovely way to bond with your baby."

Five tips Fi has for tummy time are:

• Introduce basic play by placing brightly coloured blankets or toys in-front of them to focus on and reach for

• One of the nicest ways to do tummy time is with your little one lying on top of you

• If you don't have a tummy time pillow you can use a rolled up towel or blanket to help prop your little one up in a safe position

• Never leave them unattended on their tummy and if tummy time is anywhere off the ground - ensure they are secure and can’t roll off

• Don’t worry if your little one doesn’t like tummy time at first - the more you try, the better they’ll get.

About the experts:

Dr Alexis Missick is an experienced General Practitioner who works with UK Meds. Dr Missick has worked in the NHS for over 10 years and has 6 years experience working internationally, mostly in the Caribbean. Her approach in General practice to prioritise helping patients better understand their health and engage in the process of improving it. She empowers her patients via patient education to share in their journey to better patient health and has lots of experience and knowledge relating to hair loss.

Libby Hill is an award-winning Speech & Language Therapist, to bridge the ever-widening gap between the increasing number of children with communication problems and the shortfall within the NHS.

Sophie Pickles is a BA Hons qualified infant and child development expert with a First Class degree. She is trained in paediatric first aid instruction and soon-to-be registered birth and postnatal doula. With over 16 years of experience working with hundreds of families from all over the world as an au pair, nanny, teacher, private consultant and everything in between, she's also mummy to two sons and a daughter.

Fi Star-Stone is a qualified parenting expert with 30 years working with children and families. Her qualifications include a Degree in Childhood and Youth studies, an NNEB in Nursery nursing, and a Diploma in Childhood studies

Stephanie Spencer is the Deputy Digital Editor at Mother&Baby and auntie to four aged 8 to 6 months old. With a particular interest in health, she loves discovering products that make parent’s lives easier.

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