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!!!
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