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Your 12-Week-Old Baby: Development & Growth

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12-Week-Old Baby

Table of Contents

Your baby's twelfth week after birth

Your little munchkin has been with you for three whole months now and you’re also getting used to their new routine. As parents, your sleeping schedule must be messed up and how long has it been since you’ve had the time to look after yourself? Especially new moms, understand exhaustion but one look at your little one, and it’s all forgotten. As your baby has finally reached the 12th-week mark, you must be eager to know about their developmental milestones.

In this 3-month mark, your baby undergoes yet another phase of rapid growth which will result in more feeding (possible erratic feeding times), fewer breaks, and unfortunately, late-night feeding.

Your 12-week-old baby's development and physical growth

Let us look at what is happening with your baby and in their body in terms of their physical development in the twelfth week after birth.

1. Your baby’s weight:

  • During these three months, your baby will learn a lot about what is around them. 
  • A 12-week-old baby should weigh on average around 1.5 to 1.8 kg more than what they were earlier. 
  • If your little one seems to gain a little too much weight, or a little too little weight, consult your healthcare provider about their rate of growth. 
  • Your doctor will let you know if your little one is overweight or underweight.

2. Your baby’s sleep:

  • A 12-week old baby needs 14 to 16 hours of sleep in 24 hours. 
  • They’ll usually wake up every 2 to 4 hours to eat. 
  • Although, every baby is different, which means there is a slight chance that your little one might wake up during the night and demand feeding. 
  • Besides, usually, the sleep schedule of a 12-week old baby is pretty predictable. 
  • Once they are fed, most of them sleep for a good portion of the night. 
  • If your little one is used to being cuddled to sleep, it could be a problem as they might not sleep without cuddling. 
  • As an alternative, when your baby is sleepy, lay them down and hum as they drift off to sleep. This might take a couple of days, but they’ll get used to it. 
  • Additionally, when a 12-week old baby is sleeping, keep them wrapped up as they are eager to roll around. After wrapping them up (eg swaddles), lay them securely on their back and secure their position with some small pillows.

3. Your baby’s diet: 

  • At this age, a breastfeeding baby should eat as much as they want. 
  • Approximately, your baby needs 4 ounces of breastmilk or formula every 3 to 4 hours over 24 hours. 
  • At this stage, your little one is growing rapidly so their feeding demands might increase a bit. 
  • As a baby’s maximum growth happens while they’re sleeping, they wake up with intense hunger and cry out for more food.
  • However, just because there’s an increase in demand, doesn’t mean you can switch to different food products to satisfy the need for more food. 
  • You might need to supplement breastmilk with some formula at-first because your breasts might not be able to give as much milk. 
  • Nevertheless, your body will understand the increase in demand within a couple of days, and ramps up the production of breastmilk internally.

Your newborn and 12-week-old baby's reflexes

  • When your baby is at 12 weeks, they’ll probably be in for another growth spurt. 
  • This leads to lots of crankiness, restlessness, and more feeding.
  • By now, they’ll straighten up, gain more muscle control, and their movements are less jagged. 
  • When your little one is lying on their tummy, they might even push themselves up. 
  • As your baby is playing, try laying down and encourage them to look up at you. 
  • Moreover, tummy time is extremely important. 
  • During playtime, spend a few minutes on your tummy with your baby and then build this up to 15 to 20 minutes.
  • Your baby will start to understand cause and effect because their movements are becoming much more controlled. 
  • Pretty soon, your little one will start to realize that kicking, punching things, or grabbing at toys, means that they can move.
  • Also, this is a good time to improve your baby’s sense of touch with more skin-to-skin contact. 
  • To increase bonding and help their digestive system you can try massaging your baby.

Your newborn and 12-week-old baby's health

Baby eczema:

  • Did you notice some dry, flaky, or rash skin on your little one? Well, they might have infant eczema. 
  • Usually, in babies rashes tend to start on the scalp and face. 
  • Additionally, babies with lighter pigmented skin have a pink or red version. 
  • Meanwhile, babies with darker pigmented skin have a red-brown, purplish or grayish rash.
  • Do visit your pediatrician for more information.

Ear infections:

  • Generally, babies tend to get ear infections when they catch a cold or any other upper-respiratory infection. 
  • This will lead to the lining of one of the ear tubes swelling. 
  • Then, it becomes congested and accumulates fluid.
  • Consult your healthcare provider as soon as possible.

Skin rashes:

  • If your baby has bug bites, allergies, viral and bacterial infections, it can cause itchy rashes. 
  • These itchy rashes can range from scaly or pimply to oozy. 
  • Do not worry because rest assured skin rashes are no big deal. 
  • Usually, they go away on their own or you might need some help from the doctor, who might suggest a prescription or OTC cream or medication.
  • Also, as babies have extremely sensitive skin and your baby has diaper rashes, simply use some diaper rash creams to soothe their skin.

Postpartum baby tips: Week 12 after birth

Understanding your baby’s squinting

  • As your little one is growing, their eyes are developed and the 3D vision has improved too. 
  • You might’ve noticed your baby doing a slight squint, that’s all the effort it took for them to focus. 
  • Although, if your 12-weeks-old baby is still squinting, do consult your general practitioner regarding it. 
  • This is to ensure that your little one does not have a vision problem.

Understanding flat-head syndrome

  • Does your little one doesn’t like tummy time? Do they like spending a lot of time on their back? 
  • Well, then you need to look for a flat spot on the back of your baby’s head. 
  • This flat spot is known as the flat-head syndrome. 
  • However, don’t worry about it too much because it can be managed easily.

Understanding your baby’s growing pains

  • As the 3-month growth spurt is approaching, some babies tend to become crankier. 
  • It’s completely normal for this to happen, even though they finally settled down. 
  • Due to all that growing, it takes a toll on your baby. 
  • This will make them restless and cry much more than usual. 
  • When their growth spurt comes to an end, all of this will gradually subside.

The mother's body after childbirth: What is happening in your body in the twelfth week after giving birth?

Your postnatal depression

  • During your baby’s first year, postnatal depression can occur at any time. 
  • You might want to consult your healthcare provider and talk about the possibility of postnatal depression. 
  • You might sometimes feel an overwhelming sense of guilt or failure, or you might feel like everything could go wrong and everything is your fault. 
  • One in ten women deals with postnatal depression. 
  • Remember that you are not alone!

Your post-baby exercises

  • Are you struggling to find time to fit exercise into your schedule? 
  • You need to be easy on yourself. 
  • An exercise can be something as simple as taking your baby out in the stroller.
  • Before getting back into your exercise routine, make sure you’ve gotten the green light from your general practitioner. 
  • Remember to never exercise to the point of exhaustion because you’re probably already exhausted enough (being a parent is tiring!).
  • Apart from that, if you want to lose weight after delivery, try having a brisk walk with your little one. 
  • This is a great way to meet other parents, stay healthy, and clear your mind.

You’re looking for a caregiver

  • The best way to find out about top-notch babysitters or nanny or reputable daycare centers is more often through word of mouth.
  • Don’t hesitate to ask parents for some recommendations on great infant caregivers. 
  • Some other good sources are nursery school teachers, your child’s pediatrician, and bulletin boards at your doctor’s office, library, or house of worship.
  • If you’re looking for a nanny, online agencies sell lists of pre-screened candidates. 
  • Always look into their references yourself. 
  • Make sure you’ve done a thorough background check. 
  • Moreover, do in-person interviews, along with your baby!

Final Thoughts

Some parents describe this as the beginning of the enchanted months. For the next couple of weeks, your little bundle of smiles is going to be pretty happy (hopefully), will sleep longer during nighttime (sometimes), and are not yet independent enough to move (which is less stressful for you).

Don’t be don’t hard on yourself, you’ve been doing great! Remember to take some time out for yourself and your partner!

FAQs-Your 12-Week-Old Baby

1. hat should a 3-month-old be able to do?

Here are some developmental milestones a 12-week-old can do:
  • When lying on the stomach, they can raise the head and chest.
  • When lying on the stomach, they can support the upper body with arms.
  • When lying on the stomach or back, they can stretch their legs out and kick.
  • They can open and shut their hands
  • When feet are placed on a firm surface, they can push down on their legs.
  • They can bring their hands to their mouth.
  • They can partially hold their neck.
  • They can take swipes at dangling objects with their hands.
  • 2. How do I stimulate my 12-week old baby?

    Try some of these simple things to help your baby's development at this age - You can play with them together. You can sing songs, read some books, play with toys, do tummy time and make funny sounds together. Your little one will love it and it helps you bond with your baby. Also, it makes them feel loved and secure. Try to put toys on their cot so that they try to reach it.

    3. How often should I bathe my 3 months old?

    At this age, your little one will only need a bath one to two times per week. However, if your baby loves water or splashing as they get clean, you can consider bathing them more frequently.

    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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