Your 12 Week Old Baby – Development, Milestones & Care


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A full 3 months. 90 days. That is how long you’ve been with your baby, staying awake at nights, feeding him at absurd hours, cleaning an endless supply of dirty diapers, and so on. But all of that has been worth it when you see your baby at the 12 week mark. He is grown up quite a lot and will be close to understanding the family that he has.

12 Week Old Baby Development

A 3 month mark is a huge development for you as well as your baby. Even the baby’s body realises the amount of growth that has happened, and the growth that is yet to take place. This is mostly the time when your baby will undergo yet another phase of rapid growth. This means more feeding and possibly erratic feeding times, with lesser breaks in between and even nighttime awakenings.

[Also Read: 3 Months Old Baby Development]

Twelve Week Old Baby Milestones

Within a span of 3 months, a baby tends to learn a lot of what is around him, start picking up things from people and begin understanding the call and response logic when communicating. Physically, the average weight of a 12-week-old baby is about 1.5-1.8 kg higher than what it was earlier. That physical growth is just going to keep increasing.

In the span of 12 weeks, your baby does get a hang of what’s going on around him and how things work. At least the ones related to him. Therefore, when the feeding time is imminent and he sees you approach, he will inherently understand that he is going to be fed and prepare for it. Similarly, sleeping times might also start affecting him such that he begins to fall asleep around the same time as before. These might be interrupted in the phase when growth spurt occurs.

If your child manages to get through the sleep cycle properly, it is a good time to grab all the pending sleep you missed in the last 3 months. A quarter of a full year’s growth has been successfully completed and you can have a small dinner party at your home to celebrate that, too. Keep the party short because you would want to feed your baby quickly and then doze off into a slumber the moment you get an opportunity.

[Also Read: 3 Months Old Baby Milestones]


With the rapid growth occurring around this stage, your baby’s feeding demands might ramp up a bit. At times, if the growth is substantial, there might be instances where you are barely done with one feed and it is already time for the next. A lot of energy is spent in the growing of the body and also the daily activities of your child. Maximum growth occurs while your baby sleep, which is why he might wake up with an intense hunger and cry out for food.

An increased demand for food doesn’t automatically entail switching to different food products to satisfy it. Initially, your breasts may not be able to give as much as milk as your little one requires, and you might need to supplement that with some formula. But in most cases, within a few days, your body understands the increased demand, and internally ramps up the production of breastmilk, too.

[Also Read: 3 Months Old Baby Food]


Since the growth phase is on them, there are slight chances that your baby might wake up at night and demand food. Apart from that, a 12 week old sleep schedule of the baby is pretty much in place and most of them sleep for a good portion of the night once they are fed.


Your baby might be used to being cuddled to sleep and that could soon spell a problem for you if he refuses to sleep unless cuddled. Alternatively, when really sleepy, you could lay him down on his bed and hum to him as he drifts off to sleep. A few days might be required but soon he will get used to sleeping without cuddling constantly. If you are extremely tired and have missed sleep for multiple nights, rope in your spouse to help out by preparing formula milk at night and feeding it to the baby using a bottle. If you choose to breastfeed instead, do not fall asleep with your baby on the breast since that could pose a risk of harm to both of you.

Babies at 12 weeks old will be eager to start rolling around. Therefore, keeping them wrapped up when they sleep and laying them securely on their back is more important than before. You can secure their position by using small pillows to keep them facing upwards at all times.

[Also Read: 3 Months Old Baby Sleep]


The concept of cause and effect starts developing inside your baby’s brain around this time and he begins to understand why something seems to work the way it does. If they have been used to seeing a rattle or other noisy soft toys, they will begin to understand that shaking the rattle will make the sound that they want.

Funnily, their hands will not have the coordination they require and, in the process of shaking the rattle, they may end up whacking themselves in the face. As hilarious as it might be, do ensure that your baby doesn’t harm himself and opt for using softer toys instead. With an increase in strength, the grip of your baby’s fist will soon be extremely powerful and you will start seeing that if they grab your finger, they won’t let go of it that easily. Their feet begin to move a lot and the classic foot-in-mouth tendencies begin to manifest.

At times, if your baby gets a little too excited, or make guttural sounds, you might spot some drops of milk in the mouth which he has regurgitated. This is normal as long as the amount is not too much, else it might be a sign of his vomiting. Your baby’s demeanour is a good sign for it.


It is still a long time to go before your baby stops crying without reason. But, by now, you would be at a much better position to understand what your baby is asking for when he cries. If you are one of those mothers who have a baby that seems to be crying all the time, it can soon get overwhelming. Take the help of other family members to keep your baby engaged while you go take a break for yourself. Getting angry or irritated with your baby will just aggravate his crying and leave you even more frustrated.

12 Week Old Baby Care Tips

  • The growth spurt of the baby will make him demand more food. Keep formula at hand or pump out breast milk and store it to be fed via a bottle later at night or so.
  • Make sure that no hard or sharp objects are kept near your child since his eager hands will find them in no time and start playing around.
  • Keep a routine of feeding, pooping, play and sleep that is repeated on a daily basis. Your baby will start getting used to it and feel safe and secure since he will know what to expect next.

[Also Read: 3 Months Old Baby Care]


Tests And Vaccinations

Even at the 3 month mark, no other vaccinations are necessitated by the doctor as long as all the previous vaccines around the 2 month mark have been successfully administered.

Games And Activities

As your baby grows, he begins to understand that certain sounds and what they make you feel go hand in hand. This is especially true with certain words and the same can be demonstrated to them in a fun-filled game. Using words like “clap” or “bang” and making that noise while doing a relevant facial expression can help your kid connect all the three. By understanding that when you clap your hands and say “clap clap”, they will attempt to do the same to show you, when you say clap. Babies learn a lot by mimicking us and giving them more opportunities to do the same is necessary. This can also be done with nursery rhymes or any favourite song of their kid, which brings together the excitement of listening to their favourite music and clapping along to it.

If your baby is able to hold his head up a little bit and sit up with good support, you can further strengthen your bond with him. Sitting cross-legged on a soft mattress, let your kid sit in the centre between your stomach and the crossed feet. Then, either bend over him or use a soft blanket to cover the both of you and make soft sounds. Open up the blanket and make different sounds to make your child laugh. If your spouse or other child is around, you could play peek-a-boo but join your baby in it as well.

[Also Read: 3 Months Old Baby Games and Activities]

Consult A Doctor If

Certain kids might pick up a few things later than other kids. But if your kid has barely any signs of growth, response, or recognition, such as eyes failing to follow you, or absolutely unaffected by music or sounds, it is important to get your doctor to take a look at your child.

With 3 months already completed, you might be on the verge of saying goodbye to taking care of your child. But the process has just begun and as your baby grows, he brings along new challenges, as well as new adorable behaviour to look at. These would all make the entire journey of motherhood a memorable one.

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