Prenatal
Development
Weeks 1-40
Conception
O Ovum: female cell or egg
O Uterus: organ in a woman’s body in which the
baby develops
O Sperm: male cell
O Conception: when the ovum and the sperm unite
O Ovum lives up to 24 hours after release from
ovary
O Sperm lives up to 72 hours after release from
male
Week 1
O The first week is your menstrual period.
O Your pregnancy will be dated from this:
O Most women don't know the precise moment
they have ovulated or conceived.
O Most do remember the first day of their last
menstrual period.
Week 2
O The very end of the second week marks the
release of the egg—ovulation
O At this point in your cycle, your uterine lining
is developing under the influence of
hormone your body secretes to make it
receptive to the fertilized egg.
Week 3
O Right between weeks two and three (about day
14 of a 28-day cycle) an egg will be released into
your fallopian tube—this is called "ovulation."
O Some women can tell when they ovulate by
noting mild cramping or pain or increased
vaginal discharge.
O Once the egg has been released, it must be
fertilized for you to become pregnant.
O The egg is fertilized early in the third week and
typically implants in the uterus 6-12 days after
ovulation.
Stages of the Zygote
O Zygote is the fertilized egg
O Cells will divide at rapid rate
O Within 5 days there will be over 500 cells.
O Travels down fallopian tube and attaches to
uterus
O This stage last only 2 weeks
O About the size of a pin head.
Stage of the Embryo
O Lasts from the time the cells attach to
uterus to week 12.
O Embryo: ball of rapidly multiplying cells
O Almost all of the internal organs begin to
develop during this six-week stage
O Embryo also becomes enclosed in a fluidfilled pouch called the amniotic sac.
Embryo Key Terms
O Placenta: tissue connecting the embryo to
the uterine wall.
O Umbilical cord: attaches the embryo the the
placenta.
O Amniotic fluid: fluid inside amniotic sac.
Protects the developing baby from falls that
a mother might have.
Week 4
O
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The fertilized egg is a fluid-filled cluster of rapidly multiplying cells.
The egg tunnels into the uterus where it promptly divides into two parts.
O
Half the egg attaches to the uterine wall and develops into the placenta
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The other half will develop into the embryo, which will later become the
fetus.
During this week the following occurs:
O
O
O
will transport oxygen and nutrients to your baby
Transports waste products away from your little
Spinal cord development. A sheet of cells on the back of the embryo
folds in the middle to form a tube that will become the baby's spinal
cord.
Brain section development. At the other end, the tube enlarges to form
the brain's major sections.
What's happening with you
O
O
Pregnancy symptoms
Missed period and possible spotting
Week 5
Your baby’s growth:
Embryo cell layers
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O
Just a bit bigger than an apple seed.
Embryo' has already divided into three
layers
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O
O
The top layer: Neural folds create a
tube which will form the front part of
brain, the heart which will beat this
week, and the spinal cord and back
bone
The middle layer. These cells will
produce the circulatory system,
bones, most muscles, cartilage, sex
organs and kidneys.
The bottom layer. These cells will
form the lungs, intestines and
beginnings of the urinary system.
What’s happening with
you.
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O
O
O
Missed period. You should have missed your
period or have experienced slight spotting.
Pregnancy symptoms. As your blood flow
works to catch up with your rapidly expanding
circulatory system, you may experience
morning sickness (nausea), and fatigue.
Unappetizing smells and tastes. It may help to
avoid foods with very strong smells or tastes,
such as oily or fried foods and spicy dishes.
Even strong-smelling cleaners and
disinfectants may bother you right now.
If you aren't experiencing these symptoms,
don't be concerned. You may be one of the
lucky moms who sail through early pregnancy
without feeling nauseous at all.
Week 6
Your baby’s growth
O About the size of a kidney
bean.
O Developing this week:
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Eye retina is forming
Neural tube
Heart
Limbs
Brain
Larynx and inner ear
Neck and lower jaw
Facial features
Organs
Placenta
Your body
O Breast changes.
O Become larger and more
sensitive.
O Tingling sensations
O Areola may start to darken.
O Weight change.
O May have gained two or three
pounds..
O Morning sickness.
O May get worse this week as
your hormone levels rise.
O Perfectly normal for nausea
to appear at any point of the
day or night.
Week 7
Your baby’s growth
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About 1 inch long.
Fetal digestive system is beginning to
develop. The umbilical cord, has started
taking shape. This ropelike cord
contains two arteries and a vein. It
brings oxygen and nutrients to the
embryo and carries away waste
products.
Facial features
Ears
Eyes
Head
Heart
Airways
Mouth
Skin
Your body
O Weight gain
O Morning sickness
O More bathroom
breaks
O Increased energy
Week 8
Your baby’s growth
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Head will become more rounded as the
embryo begins to look more like a baby.
Body begins to fine-tune its bone, joint
and limb development, and tiny finger
and toe buds appear.
Eyelids are forming
Nose
Blood beginning to flow
Digestive tract continues to develop
Gonads transform into either testes or
ovaries
Ears
Elbows
Vertebrae
Muscles
Skin
Your body
O Rollercoaster of
emotions
O Breast enlargement
and bigger waistline
O Cramping
O First doctor’s visit
Week 9
Your baby’s growth
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About the size of a peapod and weighs
a little less than half an ounce.
Muscles, nerves and organs are
forming.
Genitals are beginning to develop, but
it's still almost impossible to tell on
ultrasound whether you're going to have
a boy or a girl.
Increased body growth
Digits
Digestive system
Eyelids
Ears
Brain
Your body
O Increased blood
volume
O Fatigue
O Testing
O CVS
O Amniocentesis
Week 10
Baby’s growth
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Teeth
Reproductive organs
Nervous system
Internal organs
Intestines
Taste buds
Eyelids
Upper lip
Joints
Your body
O Still in regular
clothes
O Fatigue and nausea
Week 11
Baby’s growth
Fingernails
Ears
Genitalia
Swallow
Kick
Bones
Brain nerve cells connecting
All major organs will be fully
developed
O Spinal nerves
O Heartbeat
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Your body
O Uterus expansion
O Waist growth
O Skin changes: dark
line on abdomen
O Hair and nail
changes
Week 12
Baby’s growth
Had developed a facial profile
Kidneys
Pancreas
Liver
Digestive process
Brain
Pituitary gland with begin to
produce hormones
O Hair (lanugo) will appear all
over the body
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Your body
O Uterus enlargement
O Skin radiance
O Skin problems
O Nausea and fatigue
goes away
O Weight gain
Congrats!
O You have concluded the 1st trimester!
O All body parts are in place, it will just
continue to grow.
Stage of the Fetus
O 3rd and final stage of prenatal development
O Weeks 9-40
O Unborn child is called fetus
O Body, head, arms, and legs grow rapidly
O Organs continue to develop for blood
circulation, breathing, and digestion