Infancy Flashcards
Infant’s growth in the first year
Babies grow at a faster rate in their first year than at any later time of life. Birth weight doubles by the time the infant is 5 months old, and triples by the end of the first year, to about 10 kilograms on average.
Height also increases dramatically in the first year, from about 50 centimetres to about 75 centimetres, at the rate of about 2.5 centimetres per month.
Cephalocaudal principle
Where growth begins at the head and then proceeds down the rest of the body.
Proximodistal principle
Where growth proceeds from the middle of the body outwards.
First tooth
For most infants the first tooth appears between 5 and 9 months of age and causes discomfort and pain called teething.
Brain growth in infants
At birth, the brain is one-third the size of the adult brain; after birth, the brain resumes its explosive growth. Initially, the brain increases in volume by 1% per day, and by 3 months has increased 64%.
There are about 100–200 billion brain cells, or neurons, in the average infant brain. Brain growth in first year primarily involves building connections, not producing more neurons. The number of neurons at the age of 2 is about half of the amount at birth.
overproduction or exuberance
Dendritic connections multiplying vastly. By age 2, each neuron is connected to hundreds or even thousands of other cells.
Myelination
The process by which the axons become encased in a myelin sheath, an envelope of fatty material that increases the speed of communication between neurons.
Myelination is especially active in the early years of life but continues at a slower rate past the age of 40.
Synaptic pruning
As neurons create vast networks of dendrites to connect to other neurons, a process begins that enhances the precision and efficiency of the connections. ‘Use it or lose it’ is the principle that applies, as dendritic connections that are used become stronger and faster and those that are unused wither away.
The cerebellum
Part of the hindbrain, coordinates muscles and movement, and is the fastest growing part of the brain after birth, doubling its size in the infant’s first 90 days.
The hippocampus
Part of the limbic system in the forebrain, crucial in memory, especially the transfer of information from short-term to long-term memory. It is the part of the brain with the slowest growth initially, increasing only 47% in the first 90 days of life.
The cerebral cortex
Outermost part of the forebrain, far larger in humans than other animals, three to four times larger than a chimpanzee.
It accounts for 85% of the brain’s total weight, and it is here that most of the brain’s growth takes place after birth. The cerebral cortex is the basis of our distinctively human abilities, including the ability to speak and understand language, to solve complex problems and to think in terms of concepts, ideas and symbols.
Because the infant’s brain is not as specialised as it will be later in development, it is high in plasticity, meaning that it is highly responsive to environmental circumstances.
Plasticity
Because the infant’s brain is not as specialised as it will be later in development, it is high in plasticity, meaning that it is highly responsive to environmental circumstances.
Damaged parts of brain can have functions replaced, however, deprivation can also have permanent effects.
Infant’s sleep changes
By 3–4 months old, infants sleep for longer periods, up to 6–7 hours in a row at night, and REM sleep has declined to about 40%. By age 6 months, cultural practices influence how much infants sleep. Infants around 6 months old in Australia, New Zealand and the United States sleep about 14 hours, including overnight and daytime naps.
However, among the Kipsigis people of Kenya studied by Charles Super and Sara Harkness, infants slept only about 12 hours a day at 6 months of age, perhaps because they spent much of the day strapped to their mothers or an older sibling, and so expended less energy than infants in other cultures do. A study in Israel examined cultural differences among families and found significant differences in overnight sleep, with Arab infants sleeping about 1.5 hours less than Jewish infants. This difference was due to Arab children having later bedtimes and waking more at night, which is likely related to cultural parenting practices involving co-sleeping, frequent settling and soothing.
Sudden infant death syndrome (SIDS).
Infants at 2-4 months are at highest risk. Sleeping on back is a protective factor. So is sleeping in a room with parents, breast feeding, dummy use, and immunisation. Infants who die of SIDS do not have any apparent illness or disorder; they simply fall asleep and never wake up. SIDS is the leading cause of death for infants 1–12 months of age in developed countries.
Indigenous Australian infants are at much greater risk, with rates about three to four times higher than non-Indigenous infants.
Back sleeping halved mortality rates in New Zealand after campaign for awareness.
Theories for SIDS
One theory is that babies’ vulnerability to SIDS at 2–4 months old reflects the transition from reflex behaviour to intentional behaviour.
For their first 2 months of life, whenever infants’ breathing is blocked, a reflex causes them to shake their heads, bring their hands to their face and push away the cause of the obstruction. After 2 months of age, once the reflex disappears, most babies are able to do this as intentional, learned behaviour, but some are unable to make the transition, perhaps due in part to respiratory and muscular vulnerabilities.
Co-sleeping
If either parent smokes, has been using drugs or alcohol, or has taken a sedative, it is not safe to co-sleep with a baby.
Safe co-sleeping recommendations include keeping the infant on the back, using a firm mattress free from bedding that can cover the infant’s face and avoiding situations where the infant can be trapped (between the bed and a wall, pillows or two parents).
Outside the West, nearly all cultures have some form of co-sleeping during infancy. Many parents from Western cultures believe it is better for infants to have their own cot (and maybe in their own room) within a few weeks after birth.
In Japan and South Korea, almost all infants co-sleep with their mothers, and children continue to sleep with or near their mothers until puberty.
Custom complex
A distinctive cultural pattern of behaviour that is based on underlying cultural beliefs.
Parents in an individualistic culture may fear that co-sleeping will make infants and children too dependent. However, children who co-sleep with their parents in infancy are actually more self-reliant (e.g., able to dress themselves) and more socially independent (e.g., can make friends by themselves) than other children are.
Nutritional needs for infants
During the first year of life nutritional energy needs are greater than at any other time of life, per kilogram of body weight. Infants also need more fat in their diets than at any later point in life to fuel the growth of their bodies and (especially) their brains.
Marasmus
a disease in which the body wastes away from lack of nutrients. The body stops growing, the muscles atrophy, the baby becomes increasingly lethargic and eventually death results.
Introduction of solid foods
Age 4–5 months is common, in part because that is an age when infants can sit up with support and often begin to show an interest in what others are eating. Still have a gag reflex that causes them to spit out any solid item that enters their mouths.
Infant mortality
Most infant mortality is in fact neonatal mortality. That is, it takes place during the first month of life and is usually due to birth complication, infections, birth defects or preterm birth.
In Australia, infant mortality for Indigenous infants is 1.9 times higher compared to non-Indigenous infants.
Causes for infant mortality
In addition to deaths due to malnutrition, diseases are another major cause of infant mortality worldwide. Respiratory infections, primarily due to pneumococcus and Haemophilus influenzae type b (types of bacteria), are a major cause of death.
Malaria is a major killer of infants, responsible for about 1 million infant deaths per year, mainly in Africa.
Dysentery, an illness of the digestive system, is also one of the top sources of infant mortality, especially in tropical regions where dysentery bacteria thrive.
Overall, the number-one cause of infant mortality beyond the first month but within the first year is diarrhoea. In developing countries, infants who bottle-feed have a mortality rate five times higher than those who breastfeed, and many of the deaths are due to diarrhoea caused by mixing formula powder with unclean water.
COVID 19 and immunisations
23 million children missing regular vaccinations due to disruptions in health care and immunisation efforts, and 17 million did not receive a single vaccine that year. The countries that were the most critically impacted were India, Pakistan and Indonesia.
Cultural beliefs to protect children
The people of Bali, in Indonesia, believe that infants should be treated like gods, since they have just arrived from the spirit world, where the gods dwell. Consequently, for the first 3 months of life, infants should be held constantly and their feet should not touch the ground, out of respect for their godly status.
The Fulani people of West Africa believe that a sharp knife should always be kept near the baby to ward off the witches and evil spirits that may try to take its soul. Compliments to the baby should be avoided at all costs, as this may only make the baby seem more valuable and beautiful, and therefore more attractive to the evil spirits. Instead, the Fulani people believe that parents should give the infant an unattractive nickname, such as ‘Cow Turd’, so that the evil spirits will think the baby is not worth taking.
