Effects of classical music on cognitive development

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 1/120

PRINTED BY: lbethune82@email.phoenix.edu. Printing is for personal, private use only. No part of this book may be reproduced or transmitted without publisher’s prior permission. Violators will be prosecuted.

chapter 3 Prenatal Development, Birth, and the Newborn Baby

An expectant mother reacts with amazement on hearing the robust heartbeat of her nearly full-term fetus. High-quality prenatal care and preparation for the events of childbirth enable her to approach labor and delivery with confidence and excitement.

78

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 2/120

PRINTED BY: lbethune82@email.phoenix.edu. Printing is for personal, private use only. No part of this book may be reproduced or transmitted without publisher’s prior permission. Violators will be prosecuted.

chapter outline

Prenatal Development

Conception

Period of the Zygote

Period of the Embryo

Period of the Fetus

Prenatal Environmental Influences

Teratogens

Other Maternal Factors

The Importance of Prenatal Health Care

■ SOCIAL ISSUES: HEALTH The Nurse–Family Partnership: Reducing Maternal Stress and

Enhancing Child Development Through Social Support

Childbirth

The Stages of Childbirth

The Baby’s Adaptation to Labor and Delivery

The Newborn Baby’s Appearance

Assessing the Newborn’s Physical Condition: The Apgar Scale

Approaches to Childbirth

Natural, or Prepared, Childbirth

Home Delivery

Medical Interventions

Fetal Monitoring

Labor and Delivery Medication

Cesarean Delivery

Preterm and Low-Birth-Weight Infants

Preterm versus Small-for-Date Infants

Consequences for Caregiving

Interventions for Preterm Infants

78

79

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 3/120

■ SOCIAL ISSUES: HEALTH A Cross-National Perspective on Health Care and Other Policies

for Parents and Newborn Babies

Birth Complications, Parenting, and Resilience

The Newborn Baby’s Capacities

Reflexes

States

Sensory Capacities

Neonatal Behavioral Assessment

■ BIOLOGY AND ENVIRONMENT The Mysterious Tragedy of Sudden Infant Death Syndrome

Adjusting to the New Family Unit

When I met Yolanda and Jay one fall in my child development class, Yolanda was just two

months pregnant. Approaching age 30, married for several years, and their careers well

under way, they had decided to have a baby. To prepare for parenthood, they enrolled in

my evening section, arriving once a week after work full of questions: “How does the baby

grow before birth?” “When is each organ formed?” “Has its heart begun to beat?” “Can it

hear, feel, or sense our presence?”

Most of all, Yolanda and Jay wanted to do everything possible to make sure their baby

would be born healthy. Yolanda started to wonder about her diet and whether she should

keep up her daily aerobic workout. And she asked me whether an aspirin for a headache, a

glass of wine at dinner, or a few cups of coffee during work and study hours might be

harmful.

In this chapter, we answer Yolanda and Jay’s questions, along with a great many more that

scientists have asked about the events before birth. First, we trace prenatal development,

paying special attention to environmental supports for healthy growth, as well as damaging

influences that threaten the child’s health and survival. Next, we turn to the events of

childbirth. Today, women in industrialized nations have many choices about where and

how they give birth, and hospitals go to great lengths to make the arrival of a new baby a

rewarding, family-centered event.

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 4/120

Yolanda and Jay’s son Joshua reaped the benefits of his parents’ careful attention to his

needs during pregnancy. He was strong, alert, and healthy at birth. Nevertheless, the birth

process does not always go smoothly. We will consider the pros and cons of medical

interventions, such as pain-relieving drugs and surgical deliveries, designed to ease a

difficult birth and protect the health of mother and baby. Our discussion also addresses the

development of infants born underweight or too early. We conclude with a close look at the

remarkable capacities of newborns.

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 5/120

PRINTED BY: lbethune82@email.phoenix.edu. Printing is for personal, private use only. No part of this book may be reproduced or transmitted without publisher’s prior permission. Violators will be prosecuted.

Prenatal Development

The sperm and ovum that unite to form the new individual are uniquely suited for the task

of reproduction. The ovum is a tiny sphere, measuring inch in diameter—barely visible

to the naked eye as a dot the size of the period at the end of this sentence. But in its

microscopic world, it is a giant—the largest cell in the human body. The ovum’s size makes it

a perfect target for the much smaller sperm, which measure only inch.

Conception

About once every 28 days, in the middle of a woman’s menstrual cycle, an ovum bursts from

one of her ovaries, two walnut-sized organs located deep inside her abdomen, and is drawn

into one of two fallopian tubes—long, thin structures that lead to the hollow, soft-lined

uterus (see Figure 3.1). While the ovum is traveling, the spot on the ovary from which it was

released, now called the corpus luteum, secretes hormones that prepare the lining of the

uterus to receive a fertilized ovum. If pregnancy does not occur, the corpus luteum shrinks,

and the lining of the uterus is discarded two weeks later with menstruation.

The male produces sperm in vast numbers—an average of 300 million a day—in the testes,

two glands located in the scrotum, sacs that lie just behind the penis. In the final process of

maturation, each sperm develops a tail that permits it to swim long distances, upstream in

the female reproductive tract, through the cervix (opening of the uterus) and into the

fallopian tube, where fertilization usually takes place. The journey is difficult, and many

sperm die. Only 300 to 500 reach the ovum, if one happens to be present. Sperm live for up

to 6 days and can lie in wait for the ovum, which survives for only 1 day after being released

into the fallopian tube. However, most conceptions result from intercourse occurring

during a three-day period—on the day of ovulation or during the 2 days preceding it

(Wilcox, Weinberg, & Baird, 1995).

With conception, the story of prenatal development begins to unfold. The vast changes that

take place during the 38 weeks of pregnancy are usually divided into three phases: (1) the

period of the zygote, (2) the period of the embryo, and (3) the period of the fetus. As we look

at what happens in each, you may find it useful to refer to Table 3.1, which summarizes

milestones of prenatal development.

79

80

1 175

1 500

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 6/120

Period of the Zygote

FIGURE 3.1 Female reproductive organs, showing fertilization, early cell duplication, and implantation.

(From Before We Are Born, 6th ed., by K. L. Moore & T. V. N. Persaud, p. 87. Copyright © 2003, reprinted with permission from Elsevier, Inc.)

The period of the zygote lasts about two weeks, from fertilization until the tiny mass of cells

drifts down and out of the fallopian tube and attaches itself to the wall of the uterus. The

zygote’s first cell duplication is long and drawn out; it is not complete until about 30 hours

after conception. Gradually, new cells are added at a faster rate. By the fourth day, 60 to 70

cells exist that form a hollow, fluid-filled ball

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 7/120

PRINTED BY: lbethune82@email.phoenix.edu. Printing is for personal, private use only. No part of this book may be reproduced or transmitted without publisher’s prior permission. Violators will be prosecuted.

called a blastocyst (refer again to Figure 3.1). The cells on the inside, called the embryonic

disk, will become the new organism; the outer ring of cells, termed the trophoblast, will

become the structures that provide protective covering and nourishment.

TABLE 3.1 Milestones of Prenatal Development

TRIMESTER PERIOD WEEKS LENGTH AND WEIGHT MAJOR EVENTS

First Zygote 1

2

The one-celled zygote multiplies and forms a blastocyst.

The blastocyst burrows into the uterine lining. Structures that feed and protect the developing organism begin to form—amnion, chorion, yolk sac, placenta, and umbilical cord.

Embryo 3–4

5–8

¼ inch (6 mm)

1 inch (2.5 cm); ounce

(4 g)

A primitive brain and spinal cord appear. Heart, muscles, ribs, backbone, and digestive tract begin to develop.

Many external body structures (face, arms, legs, toes, fingers) and internal organs form. The sense of touch begins to develop, and the embryo can move.

80

81

1 7

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 8/120

TRIMESTER PERIOD WEEKS LENGTH AND WEIGHT MAJOR EVENTS

Fetus 9–12 3 inches (7.6 cm); less than 1 ounce (28 g)

Rapid increase in size begins. Nervous system, organs, and muscles become organized and connected, and new behavioral capacities (kicking, thumb sucking, mouth opening, and rehearsal of breathing) appear. External genitals are well- formed, and the fetus’s sex is evident.

Second 13–24 12 inches (30 cm); 1.8 pounds (820 g)

The fetus continues to enlarge rapidly. In the middle of this period, fetal movements can be felt by the mother. Vernix and lanugo keep the fetus’s skin from chapping in the amniotic fluid. Most of the brain’s neurons are in place by 24 weeks. Eyes are sensitive to light, and the fetus reacts to sound.

Third 25–38 20 inches (50 cm); 7.5 pounds (3,400 g)

The fetus has a good chance of survival if born during this time. Size increases. Lungs mature. Rapid brain development causes sensory and behavioral capacities to expand. In the middle of this period, a layer of fat is added under the skin. Antibodies are transmitted from mother to fetus to protect against disease. Most fetuses rotate into an upside-down position in preparation for birth.

Source: Moore, Persaud, & Torchia, 2013. Photos (from top to bottom): © Claude Cortier/Photo Researchers, Inc.; © G. Moscoso/Photo Researchers, Inc.; © John Watney/Photo Researchers, Inc.; © James Stevenson/Photo Researchers, Inc.; © Lennart Nilsson, A Child Is Born/Scanpix.

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 9/120

Implantation.

Between the seventh and ninth days, implantation occurs: The blastocyst burrows deep into

the uterine lining. Surrounded by the woman’s nourishing blood, it starts to grow in

earnest. At first, the trophoblast (protective outer layer) multiplies fastest. It forms a

membrane, called the amnion, that encloses the developing organism in amniotic fluid,

which helps keep the temperature of the prenatal world constant and provides a cushion

against any jolts caused by the woman’s movement. A yolk sac emerges that produces blood

cells until the liver, spleen, and bone marrow are mature enough to take over this function

(Moore, Persaud, & Torchia, 2013).

The events of these first two weeks are delicate and uncertain. As many as 30 percent of

zygotes do not survive this period. In some, the sperm and ovum do not join properly. In

others, cell duplication never begins. By preventing implantation in these cases, nature

eliminates most prenatal abnormalities (Sadler, 2010).

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 10/120

PRINTED BY: lbethune82@email.phoenix.edu. Printing is for personal, private use only. No part of this book may be reproduced or transmitted without publisher’s prior permission. Violators will be prosecuted.

Period of the zygote: seventh to ninth day. The fertilized ovum duplicates rapidly, forming a hollow ball of cells, or blastocyst, by the fourth day after fertilization. Here the blastocyst, magnified thousands of times, burrows into the uterine lining between the seventh and ninth day.

The Placenta and Umbilical Cord.

By the end of the second week, cells of the trophoblast form another protective membrane—

the chorion, which surrounds the amnion. From the chorion, tiny hairlike villi, or blood

vessels, emerge. As these villi burrow into the uterine wall, the placenta starts to develop.

By bringing the embryo’s and mother’s blood close together, the placenta permits food and

oxygen to reach the organism and waste products to be carried away. A membrane forms

that allows these substances to be exchanged but prevents the mother’s and embryo’s blood

from mixing directly.

81

82

1

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 11/120

The placenta is connected to the developing organism by the umbilical cord, which first

appears as a tiny stalk and, during the course of pregnancy, grows to a length of 1 to 3 feet.

The umbilical cord contains one large vein that delivers blood loaded with nutrients and

two arteries that remove waste products. The force of blood flowing through the cord keeps

it firm, so it seldom tangles while the embryo, like a space-walking astronaut, floats freely in

its fluid-filled chamber (Moore, Persaud, & Torchia, 2013).

By the end of the period of the zygote, the developing organism has found food and shelter.

These dramatic beginnings take place before most mothers know they are pregnant.

Period of the Embryo

The period of the embryo lasts from implantation through the eighth week of pregnancy.

During these brief six weeks, the most rapid prenatal changes take place as the groundwork

is laid for all body structures and internal organs.

Last Half of the First Month.

In the first week of this period, the embryonic disk forms three layers of cells: (1) the

ectoderm, which will become the nervous system and skin; (2) the mesoderm, from which

will develop the muscles, skeleton, circulatory system, and other internal organs; and (3) the

endoderm, which will become the digestive system, lungs, urinary tract, and glands. These

three layers give rise to all parts of the body.

At first, the nervous system develops fastest. The ectoderm folds over to form the neural

tube, or primitive spinal cord. At 3½ weeks, the top swells to form the brain. While the

nervous system is developing, the heart begins to pump blood, and the muscles, backbone,

ribs, and digestive tract appear. At the end of the first month, the curled embryo—only ¼

inch long—consists of millions of organized groups of cells with specific functions.

The Second Month.

In the second month, growth continues rapidly. The eyes, ears, nose, jaw, and neck form.

Tiny buds become arms, legs, fingers, and toes. Internal organs are more distinct: The

intestines grow, the heart develops separate chambers, and the liver and spleen take over

production of blood cells so that the yolk sac is no longer needed. Changing body

proportions cause the embryo’s posture to become more upright.

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 12/120

Period of the embryo: fourth week. This 4-week-old embryo is only ¼-inch long, but many body structures have begun to form. The primitive tail will disappear by the end of the embryonic period.

Recall from Table 2.4 on page 56 that chorionic villus sampling is the prenatal diagnostic

method that can be performed earliest, at nine weeks after conception.

1

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 13/120

PRINTED BY: lbethune82@email.phoenix.edu. Printing is for personal, private use only. No part of this book may be reproduced or transmitted without publisher’s prior permission. Violators will be prosecuted.

Period of the embryo: seventh week. The embryo’s posture is more upright. Body structures—eyes, nose, arms, legs, and internal organs—are more distinct. An embryo this age responds to touch. It can also move, although at less than one inch long and one ounce in weight, it is till too tiny to be felt by the mother.

At 7 weeks, production of neurons (nerve cells that store and transmit information) begins

deep inside the neural tube at the astounding pace of more than 250,000 per minute

(Nelson, 2011). Once formed, neurons begin traveling along tiny threads to their permanent

locations, where they will form the major parts of the brain.

At the end of this period, the embryo—about 1 inch long and ounce in weight—can

already sense its world. It responds to touch, particularly in the mouth area and on the soles

82

83

1 7

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 14/120

of the feet. And it can move, although its tiny flutters are still too light to be felt by the

mother (Moore, Persaud, & Torchia, 2013).

Period of the Fetus

The period of the fetus, from the ninth week to the end of pregnancy, is the longest prenatal

period. During this “growth and finishing” phase, the organism increases rapidly in size.

The Third Month.

In the third month, the organs, muscles, and nervous system start to become organized and

connected. When the brain signals, the fetus kicks, bends its arms, forms a fist, curls its toes,

turns its head, opens its mouth, and even sucks its thumb, stretches, and yawns. Body

position changes occur as often as 25 times per hour (Einspieler, Marschik, & Prechtl, 2008).

The tiny lungs begin to expand and contract in an early rehearsal of breathing movements.

By the twelfth week, the external genitals are well-formed, and the sex of the fetus can be

detected with ultrasound (Sadler, 2010). Other finishing touches appear, such as fingernails,

toenails, tooth buds, and eyelids. The heartbeat can now be heard through a stethoscope.

Prenatal development is sometimes divided into trimesters, or three equal time periods. At

the end of the third month, the first trimester is complete.

The Second Trimester.

By the middle of the second trimester, between 17 and 20 weeks, the new being has grown

large enough that the mother can feel its movements. A white, cheeselike substance called

vernix protects its skin from chapping during the long months spent bathing in the amniotic

fluid. White, downy hair called lanugo also appears over the entire body, helping the vernix

stick to the skin.

At the end of the second trimester, many organs are well-developed. And most of the brain’s

billions of neurons are in place; few will be produced after this time. However, glial cells,

which support and feed the neurons, continue to increase rapidly throughout the remaining

months of pregnancy, as well as after birth. Consequently, brain weight increases tenfold

from the twentieth week until birth (Roelfsema et al., 2004). At the same time, neurons

begin forming synapses, or connections, at a rapid pace.

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 15/120

Period of the fetus: eleventh week. The fetus grows rapidly. At 11 weeks, the brain and muscles are better connected. The fetus can kick, bend its arms, and open and close its hands and mouth, and suck its thumb. Notice the yolk sac, which shrinks as the internal organs take over its function of producing blood cells.

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 16/120

PRINTED BY: lbethune82@email.phoenix.edu. Printing is for personal, private use only. No part of this book may be reproduced or transmitted without publisher’s prior permission. Violators will be prosecuted.

Brain growth means new behavioral capacities. The 20-week-old fetus can be stimulated as

well as irritated by sounds. And if a doctor looks inside the uterus using fetoscopy (see Table

2.4 on page 56), fetuses try to shield their eyes from the light with their hands, indicating

that sight has begun to emerge (Moore, Persaud, & Torchia, 2013). Still, a fetus born at this

time cannot survive. Its lungs are immature, and the brain cannot yet control breathing and

body temperature.

The Third Trimester.

During the final trimester, a fetus born early has a chance for survival. The point at which

the baby can first survive, called the age of viability, occurs sometime between 22 and 26

weeks (Moore, Persaud, & Torchia, 2013). A baby born between the seventh and eighth

months, however, usually needs oxygen assistance to breathe. Although the brain’s

respiratory center is now mature, tiny air sacs in the lungs are not yet ready to inflate and

exchange carbon dioxide for oxygen.

The brain continues to make great strides. The cerebral cortex, the seat of human

intelligence, enlarges. As neural connectivity and organization improve, the fetus spends

more time awake. At 20 weeks, fetal heart rate reveals no periods of alertness. But by 28

weeks, fetuses are awake about 11 percent of the time, a figure that rises to 16 percent just

before birth (DiPietro et al., 1996). Between 30 and 34 weeks, fetuses show rhythmic

alternations between sleep and wakefulness that gradually increase in organization

(Rivkees, 2003). Around this time, synchrony between fetal heart rate and motor activity

peaks: A rise in heart rate is usually followed within 5 seconds by a burst of motor activity

(DiPietro et al., 2006). These are clear signs that coordinated neural networks are beginning

to form in the brain.

83

84

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 17/120

Period of the fetus: twenty-second week. This fetus is almost one foot long and weighs slightly more than one pound. Its movements can be felt easily by the mother and by other family members who place a hand on her abdomen. If born now, the fetus has a slim chance of surviving.

By the end of pregnancy, the fetus also takes on the beginnings of a personality. Fetal

activity is linked to infant temperament. In one study, more active fetuses during the third

trimester became 1-year-olds who could better handle frustration and 2-year-olds who were

less fearful, in that they more readily interacted with toys and with an unfamiliar adult in a

laboratory (DiPietro et al., 2002). Perhaps fetal activity is an indicator of healthy

neurological development, which fosters adaptability in childhood. The relationships just

described, however, are only modest. As we will see in Chapter 6, sensitive caregiving can

modify the temperaments of children who have difficulty adapting to new experiences.

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 18/120

Period of the fetus: thirty-sixth week. This fetus fills the uterus. To nourish it, the umbilical cord and placenta have grown large. Notice the vernix (a cheeselike substance) on the skin, which protects it from chapping. The fetus has accumulated fat to aid temperature regulation after birth. In two more weeks, it will be full-term.

 

 

7/14/2018 University of Phoenix: Development Through the Lifespan

https://phoenix.vitalsource.com/#/books/9781323102527/cfi/6/42!/4/2/2/2/2/2@0:0 19/120

PRINTED BY: lbethune82@email.phoenix.edu. Printing is for personal, private use only. No part of this book may be reproduced or transmitted without publisher’s prior permission. Violators will be prosecuted.

The third trimester brings greater responsiveness to stimulation. Between 23 and 30 weeks,

connections form between the cerebral cortex and brain regions involved in pain

sensitivity. By this time, painkillers should be used in any surgical procedures (Lee et al.,

2005). Around 28 weeks, fetuses blink their eyes in reaction to nearby sounds (Kisilevsky &

Low, 1998; Saffran, Werker, & Werner, 2006). And at 30 weeks, fetuses presented with a

repeated auditory stimulus against the mother’s abdomen initially react with a rise in heart

rate and body movements. But over the next 5 to 6 minutes, responsiveness gradually

declines, indicating habituation (adaptation) to the sound. If the stimulus is reintroduced

after a 10-minute delay, heart rate falls off far more quickly (Dirix et al., 2009). This suggests

that fetuses can remember for at least a brief period.

Within the next six weeks, fetuses distinguish the tone and rhythm of different voices and

sounds. They show systematic heart rate changes to a male versus a female speaker, to the

mother’s voice versus a stranger’s, to a stranger speaking their native language (English)

versus a foreign language (Mandarin Chinese), and to a simple familiar melody (descending

tones) versus an unfamiliar melody (ascending tones) (Granier-Deferre et al., 2003;

Huotilainen et al., 2005; Kisilevsky et al., 2003, 2009; Lecanuet et al., 1993). And in one clever

study, mothers read aloud Dr. Seuss’s lively book The Cat in the Hat for the last six weeks of

pregnancy. After birth, their infants learned to turn on recordings of the mother’s voice by

sucking on nipples. They sucked hardest to hear The Cat in the Hat—the sound they had

come to know while still in the womb (DeCasper & Spence, 1988).

In the final three months, the fetus gains more than 5 pounds and grows 7 inches. In the

eighth month, a layer of fat is added to assist with temperature regulation. The fetus also

receives antibodies from the mother’s blood that protect against illnesses, since the

newborn’s own immune system will not work well until several months after birth. In the

last weeks, most fetuses assume an upside-down position, partly because of the shape of the

uterus and also because the head is heavier than the feet. Growth slows, and birth is about

to take place.

ASK YOURSELF

REVIEW Why is the period of the embryo regarded as the most dramatic prenatal period?

Why is the period of the fetus called the “growth and finishing” phase?

CONNECT How is brain development related to fetal capacities and behavior?

84

85