Prenatal Developmentand the Newborn Period

How Children Develop (3rd ed.) Siegler, DeLoache & Eisenberg

Slides have been adapted.

Chapter 2

Overview: Major Topics

I. Prenatal Development

II. The Birth Experience

III. The Newborn Infant

Guiding Questions

1. What changes occur during prenatal development?

2. How does the environment contribute to prenatal development?

3. How does the developing child’s behavior contribute to its own development?

4. Can learning occur during the prenatal period?

5. What is daily life like for the newborn?

6. What special risks threaten the developing newborn?

Changing Ideas Over Time

Aristotle rejected the prevailing idea that the individual was preformed at the start of life in favor of epigenesis, the idea that there is an emergence of new structures and functions during development.

What changes occur during prenatal development?

The Reproductive Process

An egg is launched from one of the woman’s ovaries into the fallopian tube.

If sexual intercourse takes place near the time the egg is released, then conception will be possible.

Conception Results from the union of two gametes, the egg and the sperm Gametes are produced through a specialized cell division,

which results in each gamete’s having only half the genetic material of all other normal cells in the body.

Population sex differences begin at conception. More males are conceived, but males are more vulnerable after this point.

The Zygote After conception, the fertilized egg, or zygote, has a

full complement of human genetic material, half from each parent.

Processes Occurring During Prenatal Development

These processes transform a zygote into an embryo and then into a fetus. Cell division results in the proliferation of cells. Cell migration is the movement of cells from their

point of origin to somewhere else in the embryo. Cell differentiation transforms the embryo’s

unspecialized stem cells into different types of cells.

Apoptosis, genetically programmed cell death, also enables prenatal development.

Early Development

By the 4th day after conception, the zygote arranges itself into a hollow sphere of cells with a bulge of cells, the inner cell mass, on one side. The inner cell mass eventually forms

into the embryo.

The Embryo After implantation, the inner cell mass

becomes the embryo and the rest of the cells develop into its support system.

The neural tube is a U-shaped groove formed from the top layer of differentiated cells in the embryo. It eventually becomes the

brain and the spinal cord.

How does the environment contribute to prenatal development?

Teratogens Environmental agents that

have the potential to cause harm during prenatal development.

Timing is a crucial factor in the severity of the effects of potentially harmful agents. Many agents cause

damage only if exposure occurs during a sensitive period in development.

Most teratogens show a dose-response relation. Increases in exposure to potential

teratogens are associated with greater probabilities of fetal defects and with more severe problems.

Individual differences also influence the effects of teratogens.

Teratogens

Identifying teratogens is made difficult by the existence of sleeper effects in which the impact of a given agent may not be apparent for many years.

Teratogens include legal as well as illegal substances...

Legal Drugs: Cigarettes Cigarette smoking during

pregnancy is linked to retarded growth and low birth weight. Cigarette smoking has also

been linked to SIDS (sudden infant death syndrome), although the ultimate causes of SIDS are still unknown.

Parents can reduce the risk of SIDS by not smoking, putting babies to sleep on their backs rather than on their stomachs, using firm mattresses and no pillows as bedding for infants, and avoiding wrapping infants in lots of blankets or clothing.

Legal Drugs: Alchohol

Maternal alcoholism can lead to fetal alcohol spectrum disorder (FASD), which is associated with mental retardation, facial deformity, and other problems.

Illegal Drugs

Approximately 4% of pregnant women in the U.S. use illicit drugs.

Marijuana is suspected of affecting memory, learning, and visual skills after birth.

Cocaine-exposed children have reported cognitive and social deficits.

Environmental Pollutants

Toxic metals, synthetic hormones, and various ingredients of plastics, pesticides, and herbicides can be teratogenic.

PCBs (polycholorinated biphenyls) have been associated with small head size as newborns and slightly lower IQ scores as long as 11 years later.

Occupational Hazards

Many women have jobs that bring them into contact with potentially hazardous elements (e.g., automobile exhaust, pesticides, chemicals, noise pollution).

Maternal Factors

The age, nutrition, disease, and emotional state of the mother have an impact on prenatal development Infants born to girls 15 years or younger are three to four times

more likely to die before their first birthday than are those whose mothers 23-29 years of age.

An inadequate supply of specific nutrients or vitamins such as folic acid can have dramatic consequences.

A variety of diseases including sexually transmitted diseases present hazards to the fetus.

A woman’s emotional state can affect her fetus.

Protecting the Fetus

The placental membrane is a barrier against some, but not all toxins and infectious agents.

The amniotic sac, a membrane filled with fluid in which the fetus floats, provides a protective buffer for the fetus

How does the developing child’s behavior contribute to its own development?

The Role of Hormones

Hormones play a crucial role in sexual differentiation. All human fetuses can develop either male or

female genitalia, depending on the presence or absence of testosterone.

Fetal Behavior

By 12 weeks after gestation, most of the movements that will be present at birth have appeared. Prenatal to postnatal continuity

Swallowing amniotic fluid promotes the normal development of the palate and aids in the maturation of the digestive system.

Movement of the chest wall and pulling in and expelling small amounts of amniotic fluid help the respiratory system become functional.

Behavioral Cycles

Become stable during the second half of pregnancy

Circadian rhythms are also apparent

Near the end of pregnancy, sleep and wake states are similar to those after birth

Can learning occur during the prenatal period?

Fetal Sensory Experience

Sensory structures are present relatively early in prenatal development and play a vital role in fetal development and learning. Visual experience is negligible.

Fetus experiences tactile stimulation as a result of its own activity, and tastes and smells the amniotic fluid.

It responds to sounds from at least the 6th month of gestation.

Evidence of Fetal Learning

At 32 weeks gestation, the fetus decreases responses to repeated or continued stimulation, a simple form of learning called habituation.

Evidence of Fetal Learning

Newborn infants have been shown to recognize rhymes and stories presented before birth.

Newborns also prefer smells, tastes, and sound patterns that are familiar because of prenatal exposure.

What is daily life like for the newborn?

Newborn States of Arousal

State: The infant’s level of arousal and engagement in the environment Ranges from deep

sleep to intense activity

Is an important influence in the newborn’s exploration of the world

Six States of Arousal

1. Active sleep

2. Quiet sleep

3. Crying

4. Active awake

5. Alert awake

6. Drowsing

1. Active sleep

2. Quiet sleep

3. Crying

4. Active awake

5. Alert awake

6. Drowsing

Newborn States

Safe Sleep is Essential Newborns sleep twice as

much as young adults

The pattern of two different sleep states changes dramatically:

REM (rapid eye movement) sleep: an active sleep state associated with dreaming in adults and is characterized by quick, jerky eye movements under closed lids

Non-REM sleep: a quiet or deep sleep state characterized by the absence of motor activity or eye movements and by regular, slow brain waves, breathing, and heart rate

REM Sleep

REM sleep constitutes fully 50% of a newborn’s total sleep time and declines rapidly to only 20% by 3 or 4 years of age.

According to autostimulation theory, brain activity during REM sleep in the fetus and newborn makes up for natural deprivation of external stimuli and facilitates the early development of the visual system.

Crying

Early in infancy, crying reflects discomfort or frustration.

Crying gradually becomes more of a communicative act. With experience, parents become better at

interpreting the characteristics of the cry itself.

Crying

Many effective soothing techniques, including swaddling, involve moderately intense and continuous or repetitive stimulation.

Parents of babies with colic should seek social support and relief from frustration—and remember that colic typically ends within a few months.

What special risks threaten the developing newborn?

Infant Mortality

Death during the first year after birth (infant mortality) has become a relatively rare event in the Western industrialized world. However, rates in the United States are the 20th

highest in the world.

African-American infants are more than twice as likely to die before their first birthday as Euro-American babies.

Poverty and lack of health insurance are associated with high rates of infant mortality.

Low Birth Weight

Infants weighing less than 5.5 pounds (2,500 grams) are considered to be of low birth weight (LBW).

LBW infants born at or before 35 weeks after conception are described as premature.

Other LBW infants are referred to as small for gestation age (SGA) when their birth weight is substantially less than the norm for their gestational age.

Low Birth Weight

As a group, LBW babies experience more medical complications, have more developmental difficulties, and present special challenges for parents. However, the majority of LBW babies turn out

quite well.

Extensive parent contact and more touch for infants in neonatal intensive care are widely used interventions.

Parenting LBW Infants

Parenting LBW babies presents special challenges due to parents’ feelings of guilt and inadequacy, the stress of intensive care treatment, and the infants’ disorganized states.

Parents benefit from understanding that their preterm infants’ development will not follow the same timetable as that of a full-term infant, by learning more about infant development, and by seeking social support and intervention programs.

Multiple-Risk Models

Risk factors tend to occur together.

A negative outcome is more likely when there are multiple risk factors.

Despite multiple risk factors, however, some individuals do well.

Poverty as a Developmental Hazard

The existence of multiple risks is strongly related to socioeconomic factors.

In many countries, minority families are overrepresented in the lowest SES levels.

Risk & Resilience

Developmental resilience refers to successful development in the face of multiple and seemingly overwhelming developmental hazards.

Resilient children often experience responsive care from a particular caregiver and possess personal characteristics such as intelligence and responsiveness to others.