What are some early signs of pregnancy?
From Conception to Birth
Period of the Zygote
Period of the Embryo
Period of the Fetus
Period of the Zygote
 Begins when egg is fertilized in the
fallopian tube.
 Period of rapid cell division
 Ends 2 weeks later when the zygote is
implanted in the wall of the uterus
Period of the Zygote
Period of the Embryo
From 3 to 8 weeks after conception
Body parts are formed during this
period
 Embryo rests in the amnion filled with
amniotic fluid
 Umbilical cord joins embryo to placenta
Prenatal Structures
Period of the Fetus
From 9 weeks after conception to
birth
Increase in size and systems
begin to function
Age of viability: 22 to 28 weeks
First Month
 By the end of the
first month, the
embryo is about 1/10
of an inch long. The
heart, which is no
larger than a poppy
seed, has begun
beating.
First Month
Two Months
 The embryo is about
1 inch long and has
distinct, slightly
webbed fingers.
Veins are clearly
visible. The heart
has divided into right
and left chambers.
Two Months
Three Months
 By now the fetus is 2 1/2
to 3 inches long and is
fully formed. He has
begun swallowing and
kicking. All organs and
muscles have formed
and are beginning to
function.
Four Months
 Your baby is covered
with a layer of thick,
downy hair called
lanugo. His
heartbeat can be
heard clearly. This is
when you may feel
your baby's first
kick.
4 months
Five Months
 A protective coating
called vernix caseosa
begins to form on baby's
skin. By the end of this
month, your baby will be
nearly 8 inches long and
weigh almost a pound.
Six Months
 Eyebrows and
eyelids are visible.
Your baby's lungs
are filled with
amniotic fluid, and
he has started
breathing motions. If
you talk or sing, he
can hear you.
6 Months
Seven Months
 By the end of the
seventh month, your
baby weighs about 3
1/2 pounds and is
about 12 inches
long. His body is
well-formed.
Fingernails cover
his fingertips
Eight Months
 Your baby is gaining
about half a pound
per week, and
layers of fat are
piling on. He has
probably turned
head-down in
preparation for birth.
He weighs between
4 and 6 pounds.
Nine Months
 Your baby is a hefty
6 to 9 pounds and
measures between
19 and 22 inches. As
he becomes more
crowded, you may
feel him move
around less.
Influences on Prenatal
Development
 General Risk Factors
 Teratogens: Diseases, Drugs, and
Environmental Hazards
 How Teratogens Influence Prenatal
Development
 Prenatal Diagnosis and Treatment
General Risk Factors
Nutrition: adequate amount of food,
protein, vitamins, & minerals
Stress: decreases oxygen to fetus and
weakens mother’s immune system
Mother’s Age: neither too young, nor
too old
Teratogens: Diseases, Drugs, and
Environmental
Hazards
• Many diseases pass
through the placenta
directly and attack the
fetus
• Potentially dangerous
drugs not limited to
cocaine but include
alcohol and caffeine
• Environmental hazards
are treacherous because
we’re often unaware of
their presence
How Teratogens Influence Prenatal
Development
Not universally harmful
Harm particular structures at a
particular point in development in
particular animals
Effects of Teratogens
Prenatal Diagnosis and
Treatment
Diagnosis: ultrasound, amniocentesis,
and chorionic villus sampling can
detect physical deformities and genetic
disorders
Treatment: fetal medicine and genetic
engineering are experimental
Prenatal Diagnosis
Amniocentesis
Chorionic Villus Sampling
Labor and Delivery
 Stage 1: starts when the muscles of the
uterus contract and ends when the
cervix is fully enlarged (about 10 cm)
 Stage 2: baby is pushed down the birth
canal
 Stage 3: placenta is expelled
Three Stages of Labor
Approaches to Childbirth
• Childbirth classes
provide information
about pregnancy and
childbirth
• Childbirth classes teach
pain control through
deep breathing, imagery,
and supportive coaching
• Mothers who attend
classes use less
medication during labor
and feel more positive
about labor and birth
Birth Complications
• Lack of oxygen
(anoxia): Often
leads to surgical
removal of the fetus
(C-section)
• Premature and
Small-for-date
infants
• Prematurity is less
serious than smallfor-date
The Newborn
• Assessing the newborn:
Apgar to assess
newborns’ health; NBAS
for a comprehensive
assessment of infants
• 4 primary states: alert
inactivity, waking
activity, crying, sleeping
• Half of newborns’ sleep
is REM (deep sleep)
• Putting the baby to
sleep on their back may
prevent SIDS
Postpartum Depression
 Half of all new moms feel
some irritation, resentment,
and crying
 10-15% feel more severe
postpartum depression
 Postpartum depression
affects warmth and
enthusiasm of mothering
Happy Birthday!!!