Chapter 4 - Physical Development in Infants and Toddlers

What are the risk factors for a premature birth?

-Lack of prenatal care -Vaginal infections -Amniotic fluid infections -Short interval between birth and subsequent pregnancy -Malnutrition -Underweight or overweight before birth -Cigarette smoking -Drug use -Maternal age -Marital status -Maternal illness affecting blood vessels (high blood pressure) -Genetic background -History of spontaneous abortion or preterm labor -Physical injury or trauma -In-vitro fertilization -Multiple gestations

How many infants die of SIDS?

1/2,000 with most occurring between 1 and 3 months of age.

How big are the heads of newborns?

1/4 the newborn's total length but only 1/8 of the adult's height.

Brain Stem

At the top of the spinal cord, it controls automatic functions such as breathing and heart rate, and regulates the general level of alertness throughout higher levels of the brain.

Sudden Infant Death Syndrome

Sudden death of an infant before 1 year of age that is not explained by autopsy, medical history, or investigation of the scene of death. The cause is NOT known.

In what tribe to babies typically take their first steps at 14 months?

The Hopi tribe in Arizona, and Tewa tribe of New Mexico. 1 to 2 months later than infants in North America.

Synapses

Responsible for sending the signal to other neurons. They are the open spaces between terminal buttons of one neuron and the dendrites of the next neuron.

What is the leading cause of death for infants between 1 month and 1 year of age?

SIDS

Sucking Reflex

Something touches the infant's lips and the infant automatically begins to suck.

When do infant's usually take their first steps?

Sometime around their 1st birthday. 25% at 11 months, 25% at 13 months, 10% don't walk until 15 months.

What do researchers estimate the visual acuity in newborns to be?

Somewhere between 20/150 and 20/600.

Neurons

Specialized cells that process information and allow communication in the nervous system.

What is important to the growth and pruning of synapses?

Stimulation from the environment. Nature provides the basic materials (neurons, a brain, and nervous system), but nurture and experience are needed to sculpt and optimize the system.

Visual Acuity

The ability to see fine detail.

Spinal Cord

The body's "information superhighway" allowing for was amounts of information to be exchanged.

What body structures are already more than half their adult sizes at birth?

The brain and head.

What is one of the first structures to form when tissue differentiation begins in the embryo?

The brain.

Who are less likely to breastfeed their babies?

Younger mothers and mothers who are African American.

How big do stripes need to be for a 1-month-old infant in a visual acuity test?

At least 1/8th thick.

Broca's Area

At the bottom of the frontal lobe, organizes articulation for speech output.

DeCasper and Spence Experiment

1986, Pregnant women read aloud a particular children's story twice each day during their last 6 weeks of pregnancy. The researchers tested the newborns for recognition of the story 2-3 days after birth by using different tracks of the recording; different stories, different people. Infants chose which story they preferred by adjusting their rate of sucking on a pacifier. It appeared that the newborns adjusted their rate of sucking based on certain qualities they heard in stories. They preferred the familiar story when they were recorded by their mother over unfamiliar female voices. The results indicated that auditory perception before birth was adequate to process and retain the acoustic qualities of the story and that the newborns' perception and memory were sufficient to differentiate the two soundtracks and recognize which one was familiar.

How much do infants sleep?

1st Month: Newborns spend nearly 2/3 of their time asleep, sleeping for appx 3-4 hours at a time with only brief periods of being awake throughout day and night. 6 Weeks: Infants begin to adjust their patterns by staying awake for longer stretches during the day and sleeping more at night. This is an early indicator that cues in the environment (nurture) are exerting an influence on the infant's need for sleep (nature). 6 Months: Most are sleeping through the night. 9 Months: 70% are sleeping through the night. 2 Years: Most toddlers are sleeping through the night and are taking appx 1 nap during the day. Toddlers sleep a total of 12 to 14 hours per day.

At what age do newborns turn their heads toward the smell of their mothers?

2 weeks old.

How many infants are born in the USA earlier than 32 weeks gestation?

2%; accounting for 54% of all infant deaths.

How long is a full-term pregnancy?

38 to 40 weeks long

What is the weight of an average full-term newborn?

7.5lbs

What is the rate of low birth weight births in the USA?

8%

Low Birth Weight

A baby born weighing less than 5.5lbs.

What do most experts recommend regarding toilet training?

A child-orientated approach. Allow the child to set the pace according to their own schedule of readiness. There are psychological and emotional benefits to using this approach even though it might delay training success for several months.

What do pediatricians see serious delays in motor development as?

A potential indication of neurological or muscular deficits.

Axon

A relatively long fiber that carries electoral impulses that send messages to other cells.

Wernicke's Area

A small region on the temporal lobe, processes speech input.

NRIS

A technique that uses inferred light to measure the changes in oxygen levels in the brain.

Colostrum

A thick, yellowish substance in breastmilk containing important antibodies that are passed to the newborn. These antibodies offer infants protection against a variety of infections, viruses, and illnesses.

What are babies at lower risk for when they are breastfed?

A variety of conditions including diarrhea, respiratory infections, ear infections, diabetes, asthma, childhood obesity, lymphoma, and SIDS.

What results in healthier babies?

Access to and appropriate use of good-quality prenatal care.

What demographic has the highest rate of low birth weight births, pre-term births and infant mortality in the USA?

African American women. Twice the rate of low birth weight births. 1.5X higher rate of preterm births. 2.5X higher the rate of infant mortality.

Where are infants typically ahead of North American and European infants in major milestones?

African cultures that emphasize physical stimulation. They are ahead in sitting up and walking.

When should parents introduce juices, soft foods, and other supplements to their breastfed infants?

After 6 months

Moro Reflex

Also called Startle Reflex, occurs when an infant is startled by a loud noise or begins to fall. The noise causes the infant to extend their arms and legs outward, spread their fingers and toes, then bring their limbs back to their bodies.

How many mothers have breastfed their babies at some point?

Approximately 75%

How many neurons does the cerebral cortex contain at 20 weeks gestation?

Approximately 80 billion which is the approximate number that infants are born with.

At what age do most toddlers gain voluntary control and coordination over the muscles that control the bladder and bowel movements?

Around 18 to 24 months.

When do the first synapses form in the brain?

Around 23 weeks gestation.

When do girls typically show interest in using the toilet?

Around 24 months.

When do boys typically show interest in using the toilet?

Around 26 months. Typically 2 months later than girls.

When can infants recognize salty flavours?

Around 4 months of age.

When can infants stand by holding onto a table or other form of support?

Around 7 months.

When are infants strong enough to crawl?

Around 7 months. They push and drag their bodies around/along the floor.

When does the American Academy of Pediatrics recommend to begin breastfeeding?

As soon as possible after birth, preferably within the first hour and during the first 6 months.

When do infants prefer human voices over silence/white noise?

At 4 months of age.

At 6 months old what can an infant see?

At a distance of 10 inches, they can see stripes as thin as 1/64th an inch.

Infants as young as 3 and 4 days old prefer the smell of breast milk over bottle formula. How do we know this?

Because of NRIS techniques, it has been found that infants show greater oxygen flow in the orbitofrontal region of the brain in response to the odor of breast milk as compared to the odor of formula - even in their sleep.

Preterm Birth

Birth before 37 weeks gestation, or more than 3 weeks before the expected due date.

Intrauterine Growth Restriction (IUGR)

Born below the 10th percentile of birth weight for gestational age with no known factors that would explain the small size; indicates serious health risks. These babies fare much worse than other preterm infants. They show greater risks of infection, brain damage, and death during their first year and are more likely to show long-term problems in academic achievement as well as an increased risk of later health problems such as obesity, hypertension, and diabetes.

Dendrites

Branch like structures that receive input from other neurons.

What is linked to lower rates of SIDS?

Breastfeeding

What do nearly all health officials agree provides the best form of nutrients for most infants?

Breastmilk

When can infant's hold their head upright?

By 1 month.

When do the dendrites begin to grow?

By 20 weeks gestation.

When can infant's roll over?

By 3 months.

When has the cerebral cortex grown enough that it begins to fold inside the skull?

By 31 weeks into pregnancy (only 7-9 weeks before full term birth).

When can infants recognize their own names being spoken amid other voices?

By 5 months of age, but only if their own name is spoken more loudly than other words.

How old are infants when they respond to a broad range of sounds?

By 6 months of age.

When can infant's sit upright without support?

By 6 months.

When do infants reach 20/20 vision?

By 6-12 months.

When do the first synapses begin for form?

By the 23rd week of pregnancy.

When do infants double their birth weight?

By the time they are 5 months old.

Visual Cliff Experiment

Classic research by Gibson and Walk (1960). A heavy sheet of glass is extended across a solid surface and a deep drop off. Infants 6-14 months of age were tested. They placed the infants in the middle, then the baby's child called, first from one side and then the other. All the 6-month infants crawled out onto the solid side to reach their mothers but they refused to crawl out onto the deep side. This concluded that depth perception is available by the time infants learn to crawl. Infants 2 months of age were also known to tell the difference between the deep and solid sides. This was done by placing the infants face-down on each side of the visual cliff and measuring heart rates. In infants, heart rate deceleration indicates engrossed attention. Infants in the experiment showed significantly more slowing of their heart rates on the deep side.

Cell Body

Contains the nucleus and governs the function of the neuron.

Infant Mortality

Deaths that occur between birth and one year of age.

Brazelton Neonatal Behavioural Assessment Scale

Designed to assess the health of infants, measures some 20 different reflexes. A lack of reflexive response, or a delay in the emergence/disappearance of certain reflexes, can signal a problem with neurological development.

What are the health benefits for the mother if she breastfeeds?

Faster recovery of the uterus, less blood loss after delivery, earlier return to prepregnancy weight, reduced risks of ovarian and breast cancers, and a delay in the next ovulation which can help to increase the spacing between the next pregnancy.

In the USA, how many mothers follow the recommendation of the AAP and breastfeed their infants until the infants are at least 12 months of age?

Fewer than 1/4

Tripod Grasp

For holding pencils and other writing instruments.

When can infants begin to eat iron-rich sold foods?

From 6 to 12 months of age, they can be introduced gradually, along with breastfeeding until 12 months (and as long thereafter the infant and mother desire).

What do humans loose half of before they are even born?

Half their neurons. During migration and periods of heavy synaptogenesis, about 1/2 die in a process called programmed cell death.

Where are mothers more protective of young infants?

In some South American cultures. They tend to limit their infants' opportunities to explore and exercise motor skills. In Brazil, mothers hold/carry their infants for a large part of the day and believe that sitting or standing can damage the babies legs and spine. These babies lag behind North American infants in motor skills but they catch up around 8 months. There are similar trends in Chile, China, and Taiwan.

Visual Area

In the back of the occipital lobe, receives messages from the eyes for visual processing.

What are the effects of premature births?

Increased risk of infant mortality Increased risk of difficulties in the following: -Respiration (respiratory distress syndrome, apnea, anoxia) -Circulation, leading to brain hemorrhage -Fluid accumulation in the brain -Feeding, due to poor sucking ability -Social interactions (difficult to rouse and calm, ambiguous interpersonal signals) -Regulating sleep, awake, alert cycles Increased longer-term risk of the following: -Cerebral palsy, other neurological problems -Lowered academic achievement, lowered IQ -Attentional problems -Vision and hearing loss -Poor language development -Motor and perceptual difficulties -Specific learning disabilities -Possible increased risk of type 2 diabetes, cardiovascular disease in adulthood

What contributes to the variability in infant's walking?

Individual genetics, different rates of neurological development, and opportunities to practice muscle movements.

Pincer Grasp

Infants using their thumb and opposite forefinger. A more advanced grasp.

When might infants require a specially designed formula?

Infants who inherit certain metabolic disorders such as phenylketonuria or galactosemia.

Palmar Grasp

Infants wrapping their 4 fingers and thumb around an object.

Reflexes

Involuntary movements that are elicited by environmental stimuli such as sound, light, touch and body.

Frontal Lobe

Involved in planning, organizing, higher-level thinking, problem-solving, and creativity.

What can happen if there are disruptions in the process of programmed cell death?

It can lead to a variety of problems such as cancer, (if too few cells die), or neurological disorders such as multiple sclerosis.

Cerebral Cortex

It is the "gray matter" that forms the top portion of the brain; it is divided into four major lobes: frontal, temporal, parietal, and occipital). The many folds, convolutions, in the cortex allow a greater amount of surface area to fit within the confines of the skull.

When is normal color vision present in infants?

Its suggested that the photopigments in the eye are present by 3 months and safe to say that it is relatively mature by 6 months.

What has the second highest rate of infant mortality?

Low birth weight births; often associated with preterm birth.

Myelin Sheath

Mature axons are covered in this fatty substance that insulates the axon and speeds the axon's transmission of electrical activity.

When do infants accomplish coordinated motor actions such as sitting, reaching and standing?

Not until after the motor areas are myelinated (after 4 months).

Grasping Reflex

Occurs when an object touches an infant's palm. The babies fingers will automatically wrap around the object and grip strongly.

Cerebellum

On the back of the brain, it controls posture, body orientation, and complex muscle movements.

Synaptogenesis

One form of neuron maturation in which dendrites and axons branch out to form an enormously large number of connections with neighboring neurons. The process doesn't accelerate until late pregnancy, and most synapses form after birth, with the peak being between one and two years of age.

What is infant mortality related to?

Poor or absent prenatal care, teenage pregnancy, poor nutrition, risky health behaviors during pregnancy.

In what way does the American Academy of Pediatrics recommend infants to sleep?

Positioned on their backs in their own crib placed near the parents.

What are the potential benefits and consequences of co-sleeping?

Potential Benefits: -Can facilitate parent-infant attachments. -Might help parents notice when their infants stop breathing during a near-SIDS incident. Potential Consequences: -Infants might be suffocated or injured accidentally when they sleep with their parents and siblings contributing to a possible risk of SIDS. This is a controversial issue. Some experts say SIDS rates increase when infants co-sleep. Others disagree. Because co-sleeping occurs more frequently in ethnic minority and lower income families, it is difficult to determine if the SIDS increase is due to the co-sleeping or to other factors such as poor prenatal care associated with these families.

Co-Sleeping

Practice where infants and young children sleep with one or both parents. It is common in Sweden, in Mayan communities of Guatemala, Asian countries including China, Japan, Korea, and Thailand. In many cultures, it corresponds to cultural values of family and community. In Western countries such as the USA, it isn't as common and usually avoided. More emphasis is placed on helping the infants gain independence by moving their children into their own rooms as soon as they can sleep through the night alone. Tends to occur more often in families with parents who are African, Hispanic, or Asian American, Caucasians in rural Appalachia. It can reflect togetherness, but also the socio-economic conditions/factors in the family. Lower income families may engage in this due to necessity or with infants who are difficult to soothe/sleeping troubles.

What is one of the biggest threats faced by infants in the USA?

Prematurity

Programmed Cell Death

Process by which many neurons die during periods of migration and heavy synaptogenesis. Neural activity determines which neurons will survive by diverting the brain's energy supplies toward the neurons that are more useful and active; the neurons that are less important or not very active loose energy or die. Genetics provides an overabundance of neurons, the brain manages to chisel away at the excess until the final form is achieved. This process takes place throughout the life span, but at a much slower rate than during prenatal development.

Fine Motor Development

Process of coordinating intricate movements with smaller muscles such as finger movements.

Axon is to transmission, as dendrite is to _____________________?

Reception

Somatosensory Area

Registers sensory input including touch, pressure, temperature and pain from all areas of the body.

What causes SIDS?

Research suggests that the risk of SIDS increases when infants sleep on their bellies or sides, sleep on a soft surface, or with soft objects on their bed, or when they are overheated. The rates increase when mothers are younger below age 20, have late or no prenatal care, or smoke during pregnancy. Infants that are preterm or low in birth weight are at a greater risk. Higher rates for male infants, and infants who are African American and Native American.

Motor Area

Resembles a band; former to ear over the middle of the cortex, controls voluntary muscle movements (raising eyebrows or wiggling toes).

What pattern does gross motor development follow?

The cephalocaudal pattern. At 1 month the infants' neck muscles are strong enough to hold up the head. At 3 months they can roll over and sit upright without support at 6 months. At 7 months the legs are strong enough to crawl and stand by holding on to something supportive. Around 1 year old they take their first unaided steps. This is the head to tail pattern.

Terminal Buttons

The end of the axon branches out to form this, and it's responsive for sending the signal out to other neurons.

What is one of the last areas in the brain to be completely myelinated?

The frontal lobe. This area is still forming myelin all the way into the early 20s.

Myelination

The growth of the myelin sheath around the axon. The myelin sheath insulates the axon, which more than triples the speed of transmission of the impulse and communication with other neurons.

What happens at about 4 weeks after conception?

The human embryo folds over to form a neural tube. The neural tube later develops into the central nervous system (brain and spinal cord).

Rooting Reflex

The infant's head will turn in the direction of the touch.

What controls an infant's involuntary reflexes?

The lower brain centers: spinal cord, brain stem, and midbrain because the cerebral cortex, which governs voluntary movements, isn't well developed yet.

Communication Throughout The Nervous System

The process involves neural impulses (electrical impulses) that travel through the neurons and neurotransmitters (chemical messengers) that transmit the impulses from one neuron to the other. When the electrical impulse reaches the end of the axon, it causes the release of chemical neurotransmitters from the terminal buttons. The neurotransmitters flow across the synapse to the dendrites, where they can stimulate or inhibit the response of the neighboring cells.

Gross Motor Development

The process of coordinating movements with the large muscles in the body. These muscles control larger parts of the body such as head, neck, torso, arms and legs.

What do the cephalocaudal and proximodistal patterns mirror?

The progressive maturation of the centers in the brain. Cells and connections in the part of the brain that controls muscle movements in the head and upper body tend to mature first. Neurological development then spreads, allowing control and coordination of muscles to proceed both downward and outward throughout the body.

What pattern does reaching and grasping follow?

The proximodistal pattern. First, they reach with their arms, followed by fine motor skills of grasping with hands and fingers. Voluntary control of upper arm is around 4-5 months This is when they use the "palmar grasp." Around 10 months the "pincer grasp." At 15 months they can hold a writing implement with the palmar grasp and make scribbles using the large muscles in the upper arm. Later, they use the more precise "tripod grasp" for holding pencils/writing instruments.

The Mozart Effect

The theory that listening to classical music stimulates brain cells and increases IQ.

Dynamic Systems Theory

Thelen and colleagues; Coordinated movements such as reading, crawling, walking, and throwing are dynamic actions that emerge from the complex interplay of individual muscles, nerve pathways, physical growth, learning, and motivation. Neurological development gives infants the ability to exert voluntary control over their muscles. Parental encouragement and interesting objects in the environment motivate infants to raise their heads, turn their bodies, crawl, and take their first steps. Opportunities to exercise give babies the muscle strength they need to lift and control their growing limbs. Maturation of cognitive systems helps babies to remember where interesting objects are located and to figure out how to coordinate their movements to get them. The brain, body and the environment all work in concert to propel the child toward increased strength and coordination. How the various components work together to move the infant and child toward higher levels of development.

What traditional practice to Hopi mothers use?

They strap their infants to cradle boards and then carry the baby on their back for the first 9 months of life. They remain on these boards when nursing and sleeping. The board doesn't impede the infants walking. There is only a delay of around 2 days. All the Hopi infants take their first steps around 14 months.

How fast does an infant grow in length?

Very rapidly. On average, newborns measure just under 20 inches in length and add another 50% in their first year. by 2 years of age, children have already attained about half of their adult height.

Very Low Birth Weight

Weight less than 3.5lbs at birth (4lbs lighter than average); indicates a greater potential for health risks.

When are children ready to potty train?

When they don't show fear of the potty or bodily functions. Cognitive readiness is indicated when the child shows awareness of having soiled diapers, requests to be changed, asks to wear underwear, or shows a positive interest in the bathroom and toilet. It helps if the child is able to follow simple instructions and can stay dry for at least 2-3 hours during the day.

Are infants able to discern small differences in complicated odors?

Yes. Bottle fed newborns don't show a preference for their mothers, but breastfed infants turn their heads towards their mother's smell. This is due to repeated contact with the odor.

Can infectious diseases spread through breast milk?

Yes. HIV can spread this way. Other diseases such as tuberculosis, hepatitis B, and chickenpox. Mothers we are receiving medications for blood pressure, cancer, anxiety, depression, and even migraine headaches should consult their doctor.

Do infants have taste preferences immediately after birth?

Yes. When given a sweet solution, they smile and make sucking movements and they'll suck longer With a sour taste they purse their lips and wrinkle their noses. A bitter taste causes newborns to spit/make a face indicating disgust and rejection. These early taste preferences seem to be governed by areas in the lower brain because they appear even in infants who are born without a cerebral cortex.