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Your 15-Week-Old Baby – development & growth

Table of Contents

15-Week-Old Baby

Table of Contents

15-week-old baby – All about 4-month sleep regression and hey, is the baby rolling over on their own? Week 15 is a movement milestone as your baby, quite literally, is on a roll while you deal with some serious postpartum fatigue.

Your baby's fifteenth week after birth

At week 15, brace yourself to see your baby rock and roll! 15-week old babies typically start rolling over and will flip from their bellies to their backs. While it will be an absolute delight to see all these adult movements in your baby’s tiny body, be also prepared to wake up multiple times at right as your baby rolls to their stomach in sleep and gets stuck there. In situations like these, just gently flip your baby on their back and wait until they get the hang of flipping back on their own.

Some babies may also seem naturally inclined to sleep on their stomach and may choose to flip back to being on their stomach every time you try to make them sleep on their back – and this is absolutely OK. You may have heard that babies sleeping on their stomachs are exposed to the risk of SIDS, however, that is usually for newborn babies who are too young to be able to move their head on their own. Hence, not applicable for 15 weeks or 4-month-old babies.

Your 15-week-old baby's development and physical growth

At 15 weeks old when your little one is rolling and rocking on their own, here are some developmental changes to take note of-

  • Your baby’s cognitive development

At week 15, your baby’s cognitive mind would develop enough for them to smile, coo, and respond in their own language when you play with them. For example, if you hide your baby’s toy or play peek a boo, they will start understanding the difference between the toy or you actually not being there v/s hiding for fun. Your baby will also start responding when called out with their name in the form of turning their head and may also whiff a sense when you are not your normal self and are in any emotional state (angry, sad, etc). By now your baby will also begin understanding the meaning of the word ‘no’ and so, it may be a good idea to use your words wisely and selectively. Your baby, after all, will become what they see and learn from you!

  • Your baby’s reflexes

Roll, baby roll! Your baby in their 15th week will most likely impress you by using their own body weight to shift and to roll over on their side or back on their tummy. Try to not leave your baby unattended for a long period of time as the rolling might cause injuries and accidents. If, in case, your baby does not happen to roll as expected, do not feel disheartened and try to instead encourage them by lending a helping hand when you see them struggling. Staring at themselves in the mirror may also become one of their ‘things’ at week 15.

  • Your baby’s vision

By the time your baby turns 4 months old, their vision will almost be fully developed along with all of their other senses beginning to work together for a cohesive sensory network like that of adults. This means that babies at 15 weeks old can very well associate colors with foods; just like how adults think of a big red apple when they read or hear the word ‘apple.’ The understanding between shapes and sizes is soon to follow up.

Your 15-week-old baby's health

  • What to expect from the 4-month doctor visit

Your doctor will probably be calling you in for a 4-month checkup during your baby’s week 15 to check in on the generals like the baby’s weight, head circumference, heart rate, skin, and genitals. The pediatrician may also run tests to determine the baby’s strength and the level of motor-skill development.

  • Teething

How much drool is so much drool? Your baby in week 15 will probably be drooling a lot owing to teething. Most babies grow their first tooth between the 4th-7th month post-birth and drool remains a core element to define the personality of teething babies in general. As your baby struggles with all the wetness of their drool, investing in a couple of baby burp cloths and baby teething toys may be a good idea. You could also use a baby-safe lotion or petroleum jelly as a protective barrier against the drool because very damp skin may over time cause rashes on their sensitive skin.

  • Hand-foot-and-mouth disease

At week 15, you may also want to keep an open eye for any signs of the hand-foot-and-mouth disease which is a mild, yet contagious viral infection common in babies and children under five. The first designs of this disease are fever accompanied by a dead appetite and an excessively lethargic, cranky baby. You may also notice the development of sores in your baby’s mouth/throat and rashes (like small blisters in appearance) on their hands, feet, and butt. HFMD, though contagious, is not a serious condition as per the Centers for Disease Control and babies typically tend to recover from it within 7-10 days. Reach out to your doctor at the emergence of any first signs and do not forget to wash your hand often when tending the baby.

Postpartum baby tips: Week 15 after birth

Here’s what you should be looking out for when taking care of your baby four months into birth-

  • Feeding the baby

As your baby’s cognitive skills and abilities heighten at week 15, your baby may not want to only do one thing – eating- at one time and may give you a hard time wanting to feed and play at the same time. Babies at this age become severely curious about the world around them and hence, tend to get distracted rather easily and quickly, even in the middle of feeds. Try not to force-feed your baby as they will not only possibly throw a tantrum but may also spit out the milk causing another mess for you to take care of. it may be a good idea to try and feed your baby in environments of minimal distraction and perhaps, hold them in a way that their sight is limited to you and nothing else in the room. Be prepared for your baby to often refuse the bottle or your breast half-full, only to ask for it after some time again.

  • Your baby’s sleep pattern

As a growing curious baby, their sleep pattern will also most likely go for a toss but it will now be your responsibility as the parent to ensure that they get ample amount of sleep each night – that is, at least 15 hours each day. Known as the 4-month sleep regression, though this erratic sleep pattern may be annoying, it also is one of the biggest milestones for your little one. This regression signals your baby’s sleep patterns are changing and becoming more like those of an adult! Try and sleep next to your baby to feed him whenever they wake up at night. this may also be a good tie to buy a baby crib so that you can place them in the same room as yours, if not the same bed. You must also try and avoid singing any songs or lullabies that your baby ‘likes’ as such hummings will most likely get them excited, making it harder to put them to sleep.

Final Thoughts

As a mommy to a 4-month-old baby, exhaustion and sleep deprivation are going to be your best friends.

You may feel a lot more normal now than when you just gave birth but in actuality, your body is still recovering and has not fully gone back to what it was like pre-pregnancy. Keeping the physical aspects aside, it is no doubt that taking care of an infant can also get rather mentally exhausting and challenging at times. Hence, try and find some time for yourself to rejuvenate and to connect with yourself at least at some point during the day.

Share responsibilities with your partner, eat healthy, nutritious foods and perhaps, invest in a baby stroller to take your baby on jogs/walks which will also help you find some time in the open to reconnecting with your inner self!


1. How much milk should a 15-week old baby drink?

At week 15, you can expect your baby to drink at least 4-6 ounces (120-180 milliliters) per feed. Though this number depends on the frequency of feeding as well as the size of the baby, it is important to make sure your baby gets their daily dose of nutrition for healthy development and growth.

2. How often does a 15-week old baby eat?

15 week or 4-month-old babies are at a rapidly developing stage and so, their tummies can easily hold more milk than earlier, allowing them to eat/ feed every 3 to 4 hours.

3. At what age do babies rollover?

It is at 4 months/ 15 weeks old that babies begin to roll over from side to side and from tummy to back. However, it will take your baby another two months or so to roll in both directions.

Reviewed By-

 Nimrat, Pediatrics

Nimrat, Pediatrics

Dr. Nimrat S Sidhu is a practicing pediatrician for about 5 years now and holds an MD pediatrics degree. She was the topper of her batch, has always had a keen interest in her core medical field, and is specially trained for neonatal resuscitation.

On behalf of the editorial team at Parenthoodbliss, we follow strict reporting guidelines and only use credible sources, along with peer-reviewed studies, academic research institutions, and highly respected health organizations. To learn about how we maintain content accurate and up-to-date by reading our medical review and editorial policy.

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