Pregnancy
Mark Ewoldsen, Ph.D.
AP Environmental Science
1
Works Cited
1. Animal Development PowerPoint by Nancy G. Morris, Volunteer State Community College
@ www2.volstate.edu/msd/bio/1120/Powerpoint/Animal%20Development.ppt
2. R. Brown CO State @
http://www.vivo.colostate.edu/hbooks/pathphys/reprod/fert/fert.html
3. Web MD @ http://www.webmd.com/baby/slideshow-fetal-development
4. Baby Center @ http://www.babycenter.com/fetal-development-imagesgallery.htm#1241732358427_1
5. Wilcox et al. New Eng J Med 333:1517, 1995
6. The First Three Weeks, Thomas A. Marino, Ph.D., Department of Anatomy and Cell
Biology, Temple University School of Medicine @
isc.temple.edu/marino/2005/Early/First_Three_Weeks.ppt
Fertility
•Conception probability
• Study in healthy women
• group of 221 women were in the
trial
• data were collected from a total of
625 menstrual cycles
• 192 pregnancies were established
• 129 resulted in delivery of a baby.
11
21 day Cycle
28 day Cycle
35 day Cycle
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
18
Cycle
Begins
19
little
Fertile
20
Fertile
21
little Fertile
22
VERY
Fertile
23
VERY
Fertile
24
VERY Fertile
25
Ovulate
26
27
28
29
30
31
7
1
2
3
4
5
6
Cycle Ends
8
9
little
Fertile
11
little Fertile
12
VERY
Fertile
13
VERY
Fertile
10
Fertile
14
VERY Fertile
15
Ovulate
16
17
18
19
20
21
22
23
24
1
21 day Cycle
28 day Cycle
35 day Cycle
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
18
Cycle
Begins
19
20
21
22
23
24
25
26
little
Fertile
27
Fertile
28
little Fertile
29
VERY
Fertile
30
VERY
Fertile
31
VERY Fertile
1
Ovulate
2
3
4
5
6
7
8
9
10
11
12
13
14
Cycle Ends
19
little
Fertile
20
Fertile
21
little Fertile
15
16
17
18
22
VERY
Fertile
23
VERY
Fertile
24
VERY
Fertile
1
Ovulate
21 day Cycle
28 day Cycle
35 day Cycle
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
18
Cycle
Begins
19
20
21
22
23
24
25
26
27
28
29
30
31
1
2
little
Fertile
3
Fertile
4
little Fertile
5
VERY
Fertile
6
VERY
Fertile
7
VERY Fertile
8
Ovulate
9
10
11
12
13
14
21
15
16
17
18
19
20
Cycle Ends
22
23
24
1
21 day Cycle
28 day Cycle
35 day Cycle
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
18
Cycle
Begins
19
little
Fertile
20
Fertile
21
little Fertile
22
VERY
Fertile
23
VERY
Fertile
24
VERY Fertile
25
Ovulate
26
little
Fertile
28
little Fertile
29
VERY
Fertile
30
VERY
Fertile
31
VERY Fertile
1
Ovulate
2
little
Fertile
3
Fertile
4
little Fertile
5
VERY
Fertile
6
VERY
Fertile
7
VERY Fertile
Cycle Ends
8
Ovulate
9
little
Fertile
10
Fertile
11
little Fertile
12
VERY
Fertile
13
VERY
Fertile
14
VERY Fertile
Cycle Ends
19
little
Fertile
20
Fertile
21
little Fertile
Cycle Ends
27
Fertile
15
Ovulate
16
17
18
22
VERY
Fertile
23
VERY
Fertile
24
VERY
Fertile
1
Ovulate
Human Sexual Response
•Masters and Johnson (1957 1990s)
• Physiological responses
determined pioneered research
into the nature of human sexual
response
• Diagnosis and treatment of sexual
disorders and dysfunctions
Sexual Response Model
•Excitement (arousal)
• Erotic physical or mental stimulation,
•
kissing, petting, or viewing erotic images
• Body prepares for coitus, or sexual intercourse, in the
plateau phase
•
increase in heart rate (tachycardia)
•
increase in breathing rate
•
rise in blood pressure
•
nipple erection - nearly all females and ~60% of males
•
sex flush - ~50-75% of females and 25% of males
•
erectile tissue starting to fill
Sexual Response Model
•Plateau - period prior to orgasm
• Both Sexes
•
•
increases in circulation and heart rate
•
•
muscle tension increases
•
may begin to vocalize involuntarily
sexual pleasure increases with
increased stimulation
respiration continues at an elevated
level
Sexual Response Model
•Plateau - period prior to orgasm
• Male
•
urinary bladder closes
• prevent urine from mixing with semen
• guard against retrograde ejaculation
•
muscles at the base of the penis begin a
steady rhythmic contraction
•
may secrete seminal fluid or preejaculatory fluid
Sexual Response Model
•Plateau - period prior to orgasm
• Female
•
•
•
•
•
•
areola and labia further increase in size
clitoris withdraws slightly
Bartholin glands produce further lubrication
tissues of the outer third of the vagina swell considerably
pubococcygeus muscle tightens
•
reducing the diameter of the opening of the vagina
•
creating what Masters and Johnson refer to as the orgasmic platform
for those who never achieve orgasm, this is the peak of sexual
excitement
Sexual Response Model
•Orgasm - conclusion of the plateau phase
• Both males and females
• quick cycles of muscle contraction in the lower
pelvic muscles
• surround both the anus and the primary sexual organs
• other involuntary actions
•
•
•
•
vocalizations
muscular spasms in other areas of the body
generally euphoric sensation
heart rate is increased even further
Sexual Response Model
•Orgasm - conclusion of the plateau phase
• Males
•
•
usually associated with ejaculation
each spurt - wave of sexual pleasure
•
•
•
other sensations felt strongly - lower spine, or lower back
first and second convulsions
•
•
especially in the penis and loins
most intense in sensation/greatest quantity of semen
each contraction thereafter
•
diminishing volume of semen/milder wave of pleasure
Sexual Response Model
•Orgasm - conclusion of the plateau
phase
• Females
• experience uterine and vaginal
contractions
• may also play a significant role in fertilization
• muscular spasms aid in the locomotion of
sperm up the vaginal walls into the uterus
Sexual Response Model
•Resolution phase - after orgasm
•
Male and Female
•
•
•
•
allows the muscles to relax
blood pressure to drop
body to slow down from its excited state
may or may not experience a refractory period
•
further stimulation may cause a return to the
plateau stage
•
allows the possibility of multiple orgasms in both
Sexual Response Model
•Resolution phase - after orgasm
•
Males typically enter this refractory period (and
fall asleep)
• may find continued stimulation to be painful
•
Females do not have a similar refractory period
• can repeat cycle almost immediately.
•
Refractory periods range from human to human
• immediate (no refractory)
• as long as 12 to 24 hours
Duration of Intercourse
•Ends
•
often when man has ejaculated (and falls asleep)
•
woman might not have time to have an orgasm
•
many men suffer from premature ejaculation
•
many women require a substantially longer duration of stimulation
•Foreplay
•
on average women and men took almost the same time for sexual
arousal
•
around 10 minutes
•
time needed is very individualistic
•
varies from one time to the next
Duration of Intercourse
•Kinsey study
• under half of men reported five minutes or less
• about a fifth claimed 10 minutes or longer
• others may have taken over one hour.
•Canadian & American sex therapists
• average time was 7 minutes
• 1 to 2 minutes was too short
• 3 to 7 minutes was adequate
• 7 to 13 minutes desirable
• 10 to 30 minutes was too long
17
The Voyage
•Freshly ejaculated sperm are unable or poorly
able to fertilize
•Capacitation
• physical changes to surface and cytoplasm
• location
16
Credit: © Dr. David Phillips/Visuals Unlimited
Human Sperm entering the oviduct. SEM X500.
350626
Zonae Pellucidae
•Thick extracellular coat that
surrounds all mammalian
eggs and preimplantation
embryos
• three glycoproteins
• ZP3 allows species-specific
sperm binding
• ZP2 mediates subsequent sperm
binding
• ZP1 cross-links ZP2 and ZP3
5
Binding to Egg
• Binding of sperm to the zona pellucida
• receptor-ligand interaction
• species specificity
• Zona glycoproteins are sperm receptors
25
Fertilization - Week Two
• One sperm beats out all the others and reaches
the egg - conception
• Genetic make-up is complete
• Within three days
• divides rapidly into many cells
• passes through the fallopian tube into uterus
• attaches to the uterine wall
• placenta (nourish the baby) begins to form
35
Fertilization - Week Two
• One sperm beats out all the others and reaches
the egg - conception
• Genetic make-up is complete
• Within three days
• divides rapidly into many cells
• passes through the fallopian tube into uterus
• attaches to the uterine wall
• placenta (nourish the baby) begins to form
35
Morula Differentiation
43
Week 1
• The blastocyst consists of :
Inner Cell Mass
(embryoblast)
Trophoblast
Blastocele
Uterine Artery
Uterine Gland
Epithelium of Uterus
Inner Cell Mass
Trophoblast
Blastsocele
Week 1
Week 2
Day 7.5
Inner Cell
Mass
Cytotrophoblast
Blastocyst
Cavity
Syncytiotrophoblast
Four Weeks
nd
(2 )
•A home pregnancy test is now positive
•Ten thousand times larger than the
fertilized egg
•Structures that eventually form the face and
neck are becoming evident
•Heart and blood vessels continue to develop
•Lungs, stomach, and liver start to develop
51
QuickTime™ and a
Video decompres sor
are needed to see this picture.
49
Gastrulation
&
Neurulation
57
Hox Box
55
Five Weeks
• Brain is beginning to grow
• Eyes, legs, and hands begin to develop
63
Credit: © Mediscan/Visuals Unlimited
Human 33-day embryo measuring 7 x 3.2mm.
3597
59
Six Weeks
•Heart is beating
•Brain waves are detectable
•Mouth and lips are present
•Fingernails are forming
68
Credit: © Carolina Biological/Visuals Unlimited
Human embryo at 40 days.
214007
Credit: © Carolina Biological
Human embryo at 40 days.
213989
Credit: © Carolina Biological/Visuals Unlimited
.
Human embryo at 40 days
214006
Seven Weeks
• Baby has slightly webbed fingers and toes
• Eyelids, and toes form, nose distinct
• Baby is kicking and swimming
72
• 5 weeks after
conception
65
Credit: © Mediscan/Visuals Unlimited
Human fetus in utero at 7-weeks
3595
Eight Weeks
• Bend his elbows and knees
• About the size of a grape – almost an inch in
size
• Eyelids and ears are forming
• Tip of the nose is visible
• Arms and legs are well formed
• Fingers and toes grow longer and more distinct
• Baby is kicking and swimming
76
Nine Weeks
• Eyelids now cover eyes
82
73
75
Ten Weeks
• Hands now meet over heart
• Teeth begin to form, fingernails develop
• Baby can turn his head, and frown
• Baby can hiccup.
85
Credit: © Mediscan/Visuals Unlimited
Human fetus in utero at 10-weeks.
3594
Eleven Weeks
• Baby is busy kicking and stretching
• baby can “breathe” amniotic fluid and urinate
• Baby can grasp objects placed in its hand
• All organ systems are functioning
• Baby has a skeletal structure, nerves, and
circulation
88
Twelve Weeks
• Measures about two and a half inches
• Synapses are forming in brain
• Starts to make its own movements.
• Baby's heartbeat heard with special instruments
• Sex organs of the baby start to become clear
• Baby has all of the parts necessary to experience
pain, including nerves, spinal cord, and thalamus
• Vocal cords are complete
• Baby can suck its thumb.
90
Thirteen Weeks
• Fingerprints are new this week, and they're one of
a kind.
93
Fourteen Weeks
• Baby can grimace and squint
• At this age, the heart pumps several quarts of
blood through the body every day.
95
Fifteen Weeks
• Boy or girl? It's now possible to tell
• Baby has an adult’s taste buds
97
Sixteen Weeks
•Fetus now measures about 4.3 to 4.6
inches and weighs about 2.8 ounces
•Baby's eyes can blink
•The heart and blood vessels are fully
formed
•Fingers and toes should have fingerprints
•Bone Marrow is now beginning to form
•Heart is pumping 25 quarts of blood a day
99
Seventeen Weeks
• Baby can have dream (REM) sleep
• Baby's bones are hardening
102
Eighteen Weeks
• Baby's ears now stand out from his head.
104
• 18
• weeks
Fetal
Development
98
Nineteen Weeks
• Baby may be able to hear mother
107
Twenty Weeks
• Baby recognizes its’ mothers voice
• Baby weighs about 9 ounces
• About six inches long
• Baby is practicing swallowing
• Baby can suck a thumb, yawn, stretch, and make
faces
• Baby can be felt moving and is called "quickening"
• Earliest stage at which Partial birth abortions are
performed
109
Fetal
Development
• 20 weeks
102
Credit: © Mediscan/Visuals Unlimited
Human fetus in utero at 20-weeks. This 155-mm fetus appears to be sucking his/her thumb.
3593
Ultrasound
• An ultrasound is generally performed for all
pregnant women at 20 weeks of gestation
• Doctor will confirm that the placenta is healthy
• Attached normally
• Baby is growing properly in the uterus
• Baby's heartbeat and movement of its body,
arms, and legs can also be seen on the
ultrasound
• Gender of the baby can usually be determined
at 20 weeks
114
Twenty-one Weeks
• Eyebrows are growing in.
116
Twenty-two Weeks
• Tooth buds for baby
• Adult teeth are in place now
• Will survive childbirth
119
Twenty-three Weeks
• Dance around -- baby may be able felt
121
Twenty-four Weeks
•Baby's taste buds may be working now
•Fetus weighs about 1.4 pounds now
•Responds to sounds by moving or
increasing its pulse
•Jerking motions may be noticed if it
hiccups
•The inner ear fully developed
•May be able to sense being upside down in
the womb
123
Fetal Development
• 24 weeks
118
Last week
to get
abortion in
some states
119
Twenty-five Weeks
• Baby's hair has color and texture
127
Twenty-six Weeks
• Baby fat is building up under skin
129
Twenty-seven Weeks
• Hiccups may be common from now on.
131
Twenty-eight Weeks
•Fetus weighs about 2 pounds 6 ounces
•Baby can open eyes and blink now
•It changes position frequently at this
point in pregnancy
•Good chance of survival if baby is born
prematurely now
133
Twenty-nine Weeks
• Billions of neurons are developing in your baby's
brain.
136
Thirty Weeks
• Baby can sense a light on belly
138
Fetal Development
• 30 weeks
133
Thirty-one Weeks
• Baby can turn head from side to side
141
Thirty-two Weeks
• Fetus weighs almost 4 pounds
• Nails now cover the tips of your baby's toes and
fingers
• Baby's skin has less wrinkles as a layer of fat
starts to form under the skin
• May gain up to half its birth weight between
now and delivery
• Mother may start leaking colostrum from
breasts, a yellowish fluid that precedes milk
production
143
Thirty-three Weeks
• Baby is losing that wrinkled alien look
148
Thirty-four Weeks
• Baby's lungs are well developed
150
Thirty-five Weeks
• Most physical development is complete.
152
Credit: © Dr. Daniel Logan/Visuals Unlimited
Human Ultrasound showing fetus profile at 35 weeks.
144533
Thirty-six Weeks
• Weight gain (about an ounce a day) is baby's top priority
• Babies differ in size, depending on many factors (such as
gender, the number of babies being carried, and size of the
parents)
• On average, it's about 12.5 inches and weighs 5.5 pounds
• The brain has been developing rapidly
• Lungs are nearly fully developed
• The head is usually positioned down into the pelvis by now
• Pregnancy is considered 'at term' once 37 weeks has been
completed; baby is ready!
155
Thirty-seven Weeks
• Baby is full term!
158
Thirty-eight Weeks
• Little hands are ready to grip fingers.
160
Thirty-nine Weeks
• The average baby weighs about 7 pounds now.
162
Forty Weeks
• Baby's skull is flexible so it can squeeze through
the birth canal.
164
Forty-one Weeks
• Time to come out
• due date marks the end of her 40th week
• Pregnancy begins with implantation
• Delivery date can be calculated using the first day
of the last period
• Pregnancy can last between 38 and 42 weeks with
a 'full term' delivery occurring around 40 weeks.
167
Labor and Delivery
•
Triggered by cortisol (stress hormone)
released by offspring
•
•
•
Offspring signals the end
Prostaglandins are involved
Estrogen increases/progesterone
decreases
•
Allows uterine contractions
•
Oxytocin increases rate and strength of
contractions
170
Labor and Delivery
•
Positive Feedback Mechanism
•
increased vaginal stretch causes more oxytocin (OT) release
•
which stimulates more contraction
•
which pushes baby
•
causing more stretch
•
more OT
•
more contraction
•
more stretch
•
more OT
•
more contraction (and so on)
•
baby is delivered / positive feedback cycle is broken
170
Vaginal Childbirth (Birth) 3D Video Animation
Teratogens: “Monster Makers”
Lead
Tobacco
smoking
Alcohol
Mercury
Herbicides
Radiation
Ruebella
Syphilis
The fetus
The pregnancy
Baby's quality
of life
• Alcohol, recreational
drugs, prescription
medicines, viruses,
bacteria, toxins, etc.
• Any of the above
can be teratogens
and disrupt normal
fetal development
Health of
mother
165
Fetal Alcohol Syndrome
• Smaller heads
• Deformed facial
features
• Abnormal joints and
limbs
• Poor coordination
• Problems with learning
short memories
166
Stages of Physical Development
•
•
•
•
•
•
•
•
Neonate - “newborn”
Infancy
Toddlerhood
Childhood
Adolescence – puberty
Adulthood
Middle Age
Advanced Age
168
Motor
Development
• Motor Development
proceeds in a “down
and out” fashion.
• Head and arm control
comes before leg and
foot control.
• Control also begins in
the center of body
then to extremities
• Large muscle control
precedes control of
small muscles
169
Stages of Motor Development
• Sits without support
5-6 months
• Pulls to standing position 7-8 months
• Crawls
10 months
• Stands alone
11 – 12 months
• Walks alone
12 months
• Sequence of steps is fixed; the ages at
which they occur are not fixed
170
Toddlerhood to Adolescence
• During this period, physical growth continues,
but at a slower rate than before. Eye-hand
coordination improves dramatically.
• During adolescence, a “growth spurt” occurs.
Physical growth and development increases
rapidly.
• Puberty is the time when a person reaches sexual
maturity. Around age 11 for girls and age 13 for
boys.
• Hormones of the endocrine system cause the
onset of puberty
171
Sexual Maturity
• Estrogens in females and androgens in boys
(hormones) lead to the development of “secondary sex
characteristics.”
• Girls develop breasts, hips broaden
• Menarche is the onset of menstruation (age 12-13)
• Boys develop facial hair, voice deepens, ability to
produce semen.
• Onset of menarche was at about age 16 in 1880. This
demonstrates the impact of environment (better diet,
living conditions) on a genetically programmed
event.
172
Adulthood
• Not the same
thing as sexual
maturity
• Some cultures
have rituals that
mark the
transition to
adulthood
• Acceptance of
socially defined
responsibilities of
adulthood.
173
Aging
• Decline of physical strength,
agility, other signs of aging
begin in mid-twenties.
• Menopause (around age 50 in
women) is the cessation of
ovulation & end of menstrual
period.
• No comparable period for
men.
174
Aging and the Brain
• Brain cells are lost with
age
• Neurons that remain
“take up the slack” by
increasing complexity.
• Alzheimer’s disease
about 1% of people 65
years of age and about
20% of 80 year olds.
175