Infant Growth and Development

This blog is dedicated to all the new mummies. I am hoping to make it as easy and user friendly as possible, but please give me time to do so – I need to refine my notes, and edit this blog constantly. If you have any questions – feel free to leave a comment, or email me on

Growth is defined as “the process by which an organism or any of its parts increases in sizes”. This means PHYSICAL size, the art of unfolding biological events of an increase in length and width. Indicators for this are: mass, weight, length, body proportion, head circumference.

Development on the other hand, is very different to growth. It is defined as “a process in which something passes by degrees to a different stage (especially a more advanced or mature stage)”. It is a change in skill, increase in capacity to function that is not accidental and the ability to fulfill certain tasks. It regards the brain, and its ability to develop from a simple function of eat, sleep, poop to an incredibly complex organ that is able to multitask and carry out extremely difficult tasks, such as revoltingly difficult mathematical skills.

For an infant, growth and development are intertwined. As your infant grows, its development increases.

Thus we need to ensure that the infant is growing, to make sure that it is developing in the correct systematic stages.

This can be simply done – by measuring the baby’s weight. At a clinic, your baby’s weight (and so forth) will be measured on percentile charts and other charts, and this is very important not to lose, However, most mothers have the incorrect perception that a baby simply needs to be measured only when going to the clinic – and this is certainly not true. It is difficult to do so at home if you do not have a baby scale, but you could always go to someone who does. It is best to always use the same scale as measurements on different scales can be off by a few grams – and when we regard an infant’s weight, what may appear as a “few” grams can actually make a lot of difference!
Note: When measuring an infant, the infant must not be wearing any clothes (the gram difference is big remember?), and no nappy either (You can place the nappy above the infant’s genital parts – you know those pesky boys who like to pee all over you??).
WHY do we weigh? – We want to see if the child is gaining weight, as if the child is not then development will not take place/delayed as no energy.
HOW OFTEN should we weigh – Initially weekly, then every 2 weeks, then can prolong it. In clinic they usually only weigh the infant when vaccinated. If the infant is diagnosed as “Failure to Thrive” (whereby it will not eat and loses weight, and does not move much because it has no energy) then you can weigh until the baby’s weight is stabilized and the baby is gaining weight adequately according to age, then you can make periods longer.
REMEMBER – if you weigh the baby immediately after the baby has been fed – it will weigh more. E.g. if you bottle-feed a baby 100mls, it should gain 100g after feeding. (TEST – ensure baby is gaining weight by weighing baby before and after feeds)
BREAST vs BOTTLE – Breast feeding is once again in fashion, ladies! It provides the PERFECT amount of nutrients and fats and carbohydrates for the baby, that no formula can achieve such perfection, although they can come bloody close. However, we do understand that not every mother can or is willing to breastfeed, due to pain, lack of time, baby not willing/unable to latch and so forth. And we understand – really we do. So – I would just like to point out a few differences in your baby’s weight gain that differs with regards to Baby being fed breast milk or formula.
With breast milk – You are unable to tell how much the baby has ingested, because you “feed-on-demand”. Therefore you will NOT see as much weight gain as is always expected. Baby’s stools should also change. you should have about 8 stools in 24 hours and it will be yellowish, loose, with an acidic smell, and sometimes with white particles (Remember – baby cannot always digest things properly because its stomach cannot always handle everything at once, or certain things in the food – this is completely normal for now). When being fed on solids, stool will change in consistency and smell.
With bottle formula – you know exactly how much milk baby is taking in and therefore you WILL see more weight gain with the bottle. The stools will be a greenish colour (as formula has added iron), more formed, and more alkaline in smell. When being fed on solids, stool will change in consistency and smell.

NOTE: Mothers of newborns – Baby WILL lose 5 – 10% of its body weight during the initial days after birth, but should regain this weight within 10 days. If they do not regain this weight then Baby is having problems with feeding (Remember failure to thrive?). Babies lose this weight because of defecating the muconium (first stool –tarry black in colour, removes all the amniotic fluid that the baby swallowed in the womb) and because of frequent urination. Also if Baby is well hydrated then it should have a wet nappy of about 8 – 10 in 24 hours = well hydrated = well fed. Good on you, Mummy!

Okay, the following dsplays how many gramy baby should be gaining per day and per week according to its age. (Bear with me – I am going to try make this in a table form to amke it easier for you – okay its not working now, will try again when I get another chance!) Remeber – the first 2 years are Baby’s fastest period of growth!

–          Birth – 4 months: 30g per day (270g per week)

–          4 – 8 months: 20g per day (140g per week)

–          8 – 12 months: 15g per day as babies become more active (105g per week)

Double birth weight by 0 – 4 months, then triple, then quadruple weight by 2 years.

–          Birth: 48 – 50cm

–          6months: 65cm

–          1 yr: 75cm

–          2 yrs: 87cm

–          3 yrs: 95cm

–          4 yrs: 100cm (1m)

–          4 – 10: 100cm +6cm per year


At the clinic, Baby will be measured lying flat on a mattress with length measurements on it, and will be measured from the top of the head to its heels. Length is more or less average for boys and girls.
Please remember that genetics does play a role – e.g. if you have a tall mother and father, chances are that Baby will also be tall.
Average length measurements are:

–          Birth: 48 – 50cm

–          6months: 65cm

–          1 yr: 75cm

–          2 yrs: 87cm

–          3 yrs: 95cm

–          4 yrs: 100cm (1m)

–          4 – 10: 100cm +6cm per year

Head Circumference

Baby’s head circumference will be measured to ensure that adequate brain development takes place, and for this to occur – the brain must increase in size, which means that the skull must increase in size to accomodate the growing brain.

The baby’s head during birth is not (and should not) be fused at birth, because during a vaginal delivery, the bones of the skull will be pushed together and even overlap in order to get the head through the vaginal canal. There are 2 soft points on Baby’s head – one on the front, and one on the back, and they are shapped sort of like diamonds. They will be soft and can be very easily felt. the one on the front of baby’s head is called the anterior fontanel and the one at the back is the posterior fontanel. When the brain has grown to its correct size, they will fuse. The anterior fontanel should close at 12 – 18 months, and the posterior should close at 4 – 6months.

Factors such as genetics, race, feeding and sex can affect Baby’s head circumference. Sometimes Baby will have a big head because Daddy has a big head. This would mean Baby is normal – and there would be nothing for you to worry about. In the clinic, baby will be put on a percentile chart (Please let me know if you would like me to explain this chart to you?) to monitor head circumference. However, abnormalities can take place. A big head (not genetic) can mean a big baby, a family feature OR hydrocephalus (whereby fluids collect – small veins, bulging head, baby cannot look up, mostly brain damaged as growth cannot take place). On the other hand, Baby can have a small head, which could mean that it is a familial trait, a small baby OR that the sutures and fontanels closed too quickly (microcephaly – percentile lower than normal, brain development impacted on).

The head circumference is also generally the same for girls and boys, and the average sizes are below:

–          Birth: 34 – 35cm

–          0 – 6 months: 40cm

–          6 – 12 months: 44cm

–          1yr: 47cm

–          2 yrs: 50cm

–          5 yrs: 52cm

 Primary Reflexes

When Baby is born – it will be born with a number of primitive reflexes. Please note that Baby should be BORN with them – if Baby does not display them at appropriate age and manner, some form of developmental problem may have occurred in utero, during birth, or after the birthing process (too much oxygen for example). Below if the following Primary Reflexes:

1) The Moro reflex (present at birth. Should disappear by 3 -4 months. Presence at 4 – 6 months is abnormal (cerebral palsy?))
How to test: Hold Baby firmly by back of neck while Baby is in a sitting position facing you and gently drop baby towards a lying position and grab baby after a few cms with your other hand, to ellicit a fright reflex. This tests the quality of Baby’s muscle tone and symmetry of movement.

2) The Sucking Reflex (Essential for survival. Disappear at 1 year of age)
Tests the coordination  of the activities of sucking and swallowing and breathing – to indicate a normal Central Nervous System.
How to test: Place your finger in baby’s mouth and check to see that Baby is sucking on your finger
Will not always appear in a preemie and a mother who has ingested barbiturates due to central nervous system depression.

3) The Rooting Reflex (Essential for survival. Should disappear at age 3 – 4 months)
Tests the coordination  of the activities of sucking and swallowing and breathing – to indicate a normal Central Nervous System.
How to test: If you stroke Baby’s cheek with your nipple or finger, Baby should turn head in that direction and open his mouth (Can plop nipple in immediately to breastfeed).
If absent can indicate frontal lobe lesions.


4) Automatic Stepping/Walking Reflex (disappears at 4 – 6 weeks)
Used to evaluate normal muscular strength and tone, which enables Baby to bear weight for a short while, and tests integrity of the peripheral nervous system.
How to test: Baby will lift one foot and place it in front of the other when baby is placed vertically on a flat surface.
If remains after 3 months of age, can indicate Cerebral Palsy.

Palmar and Plantar Grasp reflexes
Palmar (Should disappear by 4 months of age – if not is indicative of frontal lobe lesions)
A strong symmetrical reaction of the hands and feet indicates integrity of the central nervous system.
How to test: Place your finger in Baby’s hand. Baby should react tightly by clasping the finger (normally in flexion)

Plantar (Should disappear by 8 months)
A strong symmetrical reaction of the hands and feet indicates integrity of the central nervous system.
How to test: Elicited in same way as palmar reflex in the dorsum of the foot, and Baby claps fingers with toes.
Should be present on BOTH feet. If not present in both or one foot –> an obstructive lesion such as an abcess or tumour means reflex will be absent on the affected side. Bilateral absence can occur in cerebral palsy.





3 responses to this post.

  1. Posted by AngelinAfrica on July 26, 2010 at 10:51

    Thanks Cybelle, some great information and I’m looking forward to the next instalments 🙂


    • They should be coming in quickly now!
      Learning so much new info and am enjoying watching people use it!
      Let me know if you have any specific questions you want me to answer.



  2. Well done TimTim!!
    Easy to read and easy to find info quickly.
    Thank you!


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