module 4 - physiology of pregnancy and birth Flashcards
(281 cards)
1
Q
the timeline of pregnancy is clinically measured as
A
gestational age
2
Q
how is gestational age calculated
A
the first day of a women Last Menstrual Period (LMP)
3
Q
gestestational age is related but distinct from _____
A
fetal age
4
Q
what is gestational age
A
refers to the age of the pregnancy
5
Q
fetal age
A
is estimated from the date of conception
6
Q
what is the average gestation (pregnancy)
A
38-40 weeks (9 months)
7
Q
each trimester length can vary
A
lengths can be different for different women but usually they are 12-14 week with a total duration of 40-42 weeks
8
Q
first trimester
A
- last from week of conception until 13th week of gestation
- rapid development in the embryo in which all organ systems are being developed
9
Q
first trimester; mom
A
- undergoes changes to accommodate the growing fetus
- increasing its blood supply to carry more nutrients and oxygen
- increased heart rate
- hormone changes ; fatigue, morning sickness, headaches, constipation
10
Q
length of second trimester
A
between 13th to about 26th week
11
Q
what happens in the second trimester
A
the uterus expands and the fetal organs continue developing
- 20th week ; hair, nails, reproductive organs form
- sex of baby can be determined
- bones and teeth harden
- nervous system becomes functional
- makes movements (kick start arouodn 20th week)
12
Q
symptoms mother feel ; second trimester
A
body aches
dizziness (due to low blood pressure)
swelling of hands and feet
13
Q
length/time of third trimester
A
lasts from week 27-birth (around 37-42 weeks)
14
Q
what happens during the third trimester
A
- fetus gains weight and grows in length
- respiratory system begin to mature just before birth
15
Q
third trimester; moms
A
- visit healthcare every 2 weeks
- maternal blood pressure and urine samples taken
- cervix and babies position to see if its in apporpatiate cephalic (head-down) position or if baby is breech (bottom-down)
16
Q
teratogens
A
any agent that has the ability to cause birth defects in the developing embryo
17
Q
what is the most vulnerable time for the embryo
A
- in the first trimester
18
Q
examples of teratogens
A
- radiation
- alcohol
- prescription medications
19
Q
when are miscarriages most often and why
A
in the first trimester because they are most vulnerable then
20
Q
clinically recognized pregnancies
A
a pregnancy confirmed by ultrasound visualization
21
Q
why do miscarriage occur
A
multiple factors but often due to chromosomal or genetic abnormalities
22
Q
preterm
A
pregnancies that result in birth before 37 weeks
- more maternal complication and worsening health outcomes for the baby
23
Q
full term pregnancy
A
carried 37-40 weeks
- optimal delivery
- after 41 weeks are later term
24
Q
post term
A
carried beyond 42 weeks
- risks for complications increase significantly for both mother and fetus
- doctors will induce labour between 41-42 weeks
25
postnatal period puerperium
mother undergoes physical and psychological changes as the body return to pre pregnancy condition
26
what is Naegeles rule
standard way of calculating the delivery date for a pregnancy under the common assumption of a gestational age of 280 days at childbirth
27
what are the 3 steps to use Naegeles rule
1. determine when was the first day of your last menstural period (LMP)
2. count back 3 calendar months from the previous date
3. add 1 year and 7 days to that date
28
the babies development can be divided into 2 major stages what are they
embryonic stage and fetal stage
29
embryonic stage
comprises the first 8 weeks of develop (fetal age) and the developing offspring is called the embryo
- first trimester characterized by major morphological changes
30
the carnegies stages of the embryonic period
- embryo development is hard to track by chronological age or size
- embryologist (franklin P mall) was the fitst person to stage the development of human embryos he creates Carnegies stages
31
fetal stage what is it
- after the 8th weeks of development (10 weeks gestation after carniegie stage 23)
- offspring is called fetus
- end of the first trimester and extends until birth
- characterized by growth and continued development of the structures established during the embryonic stage
32
what happens in 0-2 weeks of embryonic timeline
- carnegies stages
33
carnegies stages 1-6
- the zygote travels towards the uterine cavity
and undergoes cleavage
- reaches the uterus, it has become a blastocyst.
- After hatching
from the zona pellucida, the blastocyst implants into the uterine wall and eventually develops the
germ layers that will give rise to organ systems.
34
week 3-4 embryonic timelines
carniegies stages 7-13
35
carniegies stages 7-13
- body plan is established.
- early blood vessels, red blood cells and primitive hear appear in week 3 by week 4 a primitve heart beats around 113per/min (first functioning organ)
36
carniegies stages 7-13; mesoderm layer
begins its differentiation into muscle, kidneys,
bones, and heart,
37
carniegies stages 7-13; ectoderm
into the nervous tissues and skin
38
carniegies stages 7-13; endoderm
into the
digestive tract, lungs, and liver.
39
carniegies stages 7-13; Primordial germ cells
begin to migrate towards the gonadal ridges. Wolffian and Müllerian ducts
begin to form.
40
week 5 of embryonic timeiline
Carnegie stages 14-15
41
Carnegie stages 14-15
- The four major chambers of the heart become visible (the primitive heart which begins beating in Week
3, consists of only two, joined, contractile tubes).
- Upper and lower limbs begin to grow. - The future cerebral hemispheres
become visible.
42
week 6 of embroynic timeline
Carnegie stages 16-17
43
Carnegie stages 16-17
Primordial germ cells arrive at and invade the gonadal ridges. The heart and lungs begin to descend
into the thorax. The heart starts to beat at a regular rhythm.
44
Weeks 7-8 of embryonic timeline
Carnegie stages 18-23
45
Carnegie stages 18-23
- embryo transitions into the fetal stage
- Fingers become visible
- Cartilage begins to be replaced by
bone
- gonads differentiate
(males) primitive testes begin their slow descent
46
when does fetal stage being in carnegie stages
stage 23 around week 9 of gestation
47
Fetal Age: 8 weeks
(kumquat)
tail disappears and it is now called a fetus. The fetus is about
3 c m long and weighs roughly 35g.
48
Fetal Age: 11 weeks
lemon
- fetus is now 6.5 c m long and weighs about 75g. All the major organs have formed.
49
Fetal Age: 14 weeks
avocado
- fetus is now around 18 c m long and weighs approximately 150g.
50
51
Fetal Age: 21 weeks
grapefruit)
The fetus has grown to be 30 c m long and weighs about 560g
52
Fetal Age: 29 weeks
coconut
- e fetus is now around 42 c m long and weighs roughly 1.4 k g.
53
Fetal Age: 38 weeks
watermelon
- Right before birth the fetus is approximately 52 c m long and weighs roughly 3.6 k g.
54
why is knowing the maternal physiological changes and fetal developmental stages important
- key to the monitoring of maternal and fetal health during pregnancy
- used to inform current guidelines in maternal and fetal tests, optimal nutrition during pregnancy, and for the prevention and treatment of complications commonly experienced during pregnancy and preventative
interventions for fetal complications
55
why might ultrasound evaulation be used
- Confirm pregnancy and location
- Confirm number of babies
- Determine gestational age
- Evaluate fetal growth
- Evaluate placenta and fluid levels
- Identify birth defects
- Determine fetal position before delivery
- Other prenatal tests
56
Confirm pregnancy and location
Can be used to detect an ectopic pregnancy
57
Determine gestational age
Can be used to determine the due date of the baby and track important milestones.
58
Evaluate fetal growth
An ultrasound can determine if the fetus is growing at a normal rate. They can monitor movement,
breathing, and heart rate.
59
Evaluate placenta and fluid levels
The placenta provides nutrients and oxygen-rich blood, while the amniotic fluid protects the fetus.
Both are critical during pregnancy.
60
Amniotic fluid:
The fluid that surrounds the fetus in the uterus during pregnancy.
61
what is the placenta
is a temporary organ that develops from both maternal and fetal tissues
- helps the development of the fetus by reuglating its nutrient uptake, thermo-regulation, waste elimination, gas exchanges via mothers blood supply
62
human placenta is a what
hemochorial, which is the most invasive type
63
three main types of placental structures
- epitheliochorial
- endotheliochorial
- hemochorial
64
Epitheliochorial ; placental structures
- least invasive type, where maternal blood is kept separate from fetal tissues by three maternal
tissue layers
- This placenta is observed in cows, pigs, and horses
65
what keeps maternal blood separate from fetal tissues in Epitheliochorial
maternal tissue layers: endothelium, connective tissue, and epithelium.
66
Endotheliochorial; placental structures
Maternal blood is separated from the fetal membranes by a layer of maternal endothelium and some
interstitial tissue.
- in dogs and cats.
67
Hemochorial
The human placenta allows the fetal membranes to be bathed directly with maternal blood.
- humans, mice and rabbits
68
primary functions of the placenta
- Nutrient and Oxygen Exchange
- Protection
- Hormone production
- Excretion
- Attachment to Uterine Wall
69
Nutrient and Oxygen Exchange ; placenta
- supply adequate nutrition to the growing fetus.
- regulates the exchange of oxygen, carbon dioxide, and other nutrients.
70
Protection; placenta
acts as a barrier, reducing fetal exposure to xenobiotic substances that may be harmful
to the fetus.
71
Hormone production; placenta
releases a number of key hormones into fetal and maternal circulation that regulate maternal metabolism, fetal growth, as well as other functions.
72
Excretion ; palcenta
Waste products from the fetus diffuse across the placenta to the maternal blood where they may be
excreted through the mother’s urine.
73
Attachment to Uterine Wall; palcenta
All of the other functions of the placenta are made possible by the proper anchoring of the placenta to
the uterine wall
74
Xenobiotic
A substance that is foreign to the body.
75
when does a placenta start to form
as soon as implantation starts
- after the embryo survive the pre-implantation period and manages to form the initial attachment to the uterine wall, buries itself into the decidua
76
what does the invasion of embryo mark
the beginning of placental formation
77
human placental formation begins when?
the trophectoderm or trophoblast layer, the outer layer of cells that first appears during the blastocyst stage initiates the attachment of the maternal decidua
78
around day 9 post-fertilization
- the trophoblast cells grow and invade the decidua, anchoring and invading the uterine surface to try to reach and access the maternal blood vessels.
79
After this initial invasion (about 7 days post fertilization)
- trophoblasts differentiate into two
cell types, the cytotrophoblast and the syncytiotrophoblast
80
what is the syncytiotrophoblast layer
- composed of cytotrophoblast cells that fuse together into a
multinucleated, continuous cell layer (without cell borders) known as a syncytium
- comprises the
outermost layer of the trophoblast cells and it actively migrates and invades the decidua
81
what will the syncytiotrophoblas become
the blood-placental barrier
82
the blood-placental barrier
regulate efficient nutrient/gas exchange, enabling the production of placental hormones, and regulating immune tolerance of the fetus by the maternal immune system
83
As the syncytiotrophoblast layer expands
hollow spaces begin to form called lacunae.
- which will grow and fuse into a larger space known as the intervillous space
84
Cytotrophoblasts
comprise the inner layer of trophoblast cells, which produce proteolytic enzymes to facilitate the invasion of the decidua
- have a clear cell border and a single nucleus.
85
Cytotrophoblasts replenish what
the cells of the outer syncytium layer, and are thus called germinal cells of the syncytium
86
differentiation of the inner cell mass
- blastocyst invades the decidua until it becomes fully encased within the endometrium
- out trophoblast layer differentiates and invades the decidua (inner of blastocyt also develop)
87
what does the inner cell mass of blastocyst form
a flattened bilayered embryonic disc consisting of the epiblast and hypoblast
88
epiblast
give rise to all embryoonic structures
89
hypoblast
supports the development of the embryo
90
around day 9 what does the hypoblast give rise to
extraembryonic mesoderm
91
extraembryonic mesoderm
a layer of cells between
the outer cytotrophoblast layer and inner cell mass, which will later support the development of key
structures, such as the amnion, the yolk sac, and the chorionic villi of the placenta
92
formation of the chorionic villi
- once implantation is complete, cytotrophoblast layer continues to grow, and the cells form finger like projections through the syncytium known as chorionic villi
93
what are the different chorionic villi depending on stage
- primary
- secondary
- tertiary
94
Primary Villi formation
form as the cytotrophoblast cells invade and protrude into the syncytiotrophoblast layer
95
about Primary Villi
small and avascular, with a cytotrophoblast core surrounded by a layer of syncytium
96
Secondary Villi composition
extraembryonic mesodermal core and are covered by a layer of cytotrophoblast cells and an outer syncytiotrophoblast layer
97
Tertiary Villi
As the embryonic blood vessels develop in the mesodermal core of secondary villi, they become
tertiary villi.
98
what do tertiary villi have
an extraembryonic mesodermal core with villous capillaries, and are covered by a
cytotrophoblastic and syncytiotrophoblastic layer
99
what happens as tertiary villi continue to grow
- cytotrophoblasts will invade and pass through the syncytiotrophoblast
layer to come in direct contact with the maternal decidua
- and they will proliferate laterally to form a cytotrophoblast shell
100
cytotrophoblastic shell
surrounds the syncytiotrophoblasts and the entire embryo
101
Large tertiary villi
connect to cytotrophoblastic shell to the chroionic plate and are known as anchoring willi
102
what will anchoring villi branch to
floating villi
103
intervillous space
- space between the villi between the chorionic shell and chorionic plate
104
what happens in the intervillous space
is where the maternal circulation will pool and bathe the chorionic villi
105
the shell and the chorionic plate surrond the ___ and form the ____
embryo, chorion
106
Chorionic plate
The base, the fetal side of the placenta, from which chorionic villi originate.
107
Chorion:
A double-layered membrane formed by the cytotrophoblastic shell and the chorionic plate. This structure forms the outermost covering of the embryo, amnion, and yolk sac, and will eventually give rise to the fetal side of the placenta.
108
what villi grow asymmetrically + where
teritary villi
- growing at the anchoring side of the embryo where it faces the maternal decidua
109
what is the highly villous area known as
chorion frondosum
(fetal side of the placenta)
110
villi on the opposite side of the chorion fondosum
will atrophy, creating a smooth muscle surface known as the chorion leave
111
decidua basalis
side of the decidua where the chorion frondosum attaches and grows
112
what is the other side of the deciuda where chorion frondosum doesnt attach to called
decidua capsularis
113
decidua capsularis
does not interact with chorionic vill and will become smooth layer
114
where will the fetus grow
inside the extraembryonic membranes
115
extraembryonic membranes
are the additional layers that
project from the placenta and surround the fetus to protect and assist in its development.
116
fetal membranes
Amnion
Yolk sac
Allantois
Chorion
Extraembryonic coelom
117
Amnion
- The innermost membrane that surrounds the embryo.
- transparent membrane
- contains amniotic fluid
118
amniotic fluid
protects the embryo from mechanical stress and impact.
119
Yolk sac
- A small sac on the ventral surface of the embryo
- most important functions occur in early pregnancy (source of primordial germ cells and blood cells)
- It regresses in later
stages of pregnancy
120
Allantois
A hollow sac on the tail end of the yolk sac. It contributes to nutrition and excretion, and helps form the
umbilical cord.
121
Chorion
The outermost fetal membrane, it surrounds all other membranes and the embryo, and forms the fetal
side of the placenta
122
what does the chorion include
the chorion frondosum and chorion laeve
123
Extraembryonic coelom
The space between the amnion and the chorion.
124
spiral artery remodeling
The blood vessels that supply the uterus are characterized as having a spiral shape, particularly in the
basal layer of the endometrium (the side in contact with the myometrium)
- and supply the placenta and growing fetus
125
extravillous trophoblasts
A highly invasive type of cytotrophoblast arises from the tips of anchoring villi
126
extravillous trophoblasts where do they go and do
will migrate towards the maternal arteries (not the veins), and cause major modifications of their walls (spiral artery remodeling)
127
what is sprial artery remodelling a critical step for
in the establishment of the placenta, as these arteries will feed into the intervillous space, where the maternal blood comes into contact with the fetal membranes.
128
spiral artery remodeling ; early pregnancy
The extravillous trophoblasts proliferate from anchoring villi and invade the maternal decidua.
129
spiral artery remodeling ; End of First Trimester
Extravillous trophoblasts differentiate into two types.
130
what are the 2 types do extravillous trophoblasts differentiate into
- interstitiaial extravillous trophoblasts
- endovascular extravillous trophoblasts
131
interstitiaial extravillous trophoblasts
these cells invade deeper into the decidua and surround the
spiral arteries.
132
Endovascular extravillous trophoblasts:
these cells penetrate the lumen of the uterine spiral arteries
133
spiral artery remodeling; Midgestation
Both types of extravillous trophoblasts are involved in the degradation of maternal vascular endothelium, and the replacement of smooth muscle and connective tissue of the arteries with fibrous material.
- maternal spiral arteries become wider, which decreases vascular resistance and
allows a higher volume of blood flow compared to normal arteries.
134
spiral artery remodeling;; 3rd Trimester
the blood supply to the uterus and placenta has increased by a factor of 10 compared to the non-pregnant uterus as a result of spiral artery remodeling
135
placental ciruclation
acts as the interface between two circulatory systems : uteroplacental (maternal-placental) blood circulation and the fetoplacental blood circulation
136
fetoplacental blood circulation
- fetus is attached to the placenta via the umbilical cord
- umbilical cord connects to the
placenta and is not directly connected to the mother’s circulatory system, it transports oxygen and
nutrients to and from the mother’s blood without allowing direct mixing
137
umbilical cord contains
three vessels
- One umbilical vein
- Two umbilical arteries
138
One umbilical vein
Carries oxygenated, nutrient-rich blood from the placenta to the fetus
139
Two umbilical arteries
Carries deoxygenated, nutrient-depleted blood from the fetus to the placenta.
140
uteroplacental (maternal-placental) blood circulation
begins around the end of the first trimester, although maternal blood
vessels continue to be remodeled until the third trimester
- Maternal blood flows from the uterine spiral arteries into the intervillous space, allowing for the
exchange of oxygen and nutrients between maternal blood and the fetal blood vessels within the chorionic villi
- The in-flowing maternal arterial blood pushes deoxygenated blood into the endometrial veins and back into the maternal circulation.
141
maturation of the placenta
- continues to grow in thickness and circumference until the end of the fourth month of
gestation
- increased thickness of placenta is the result of the lengthening and branching of the villi
in the chorion frondosum, and expasnio of the intervillous space
142
after the 4th moth of pregnancy ; placenta
no longer increases in thickness, but as the fetus grows, the circumference of the placenta continues to increase throughout the remainder of the pregnancy
143
the placenta as an immune barrier
The fetus grows in an isolated environment created by the placenta and the extraembryonic
membranes
144
where do all nutrients and molecule need by fetus come through
feto-placental
barrier
145
feto-placental barrier creation
created by the syncytiotrophoblasts that enclose the intervillous space.
146
feto-placental barrier 2 functions
Prevent maternal immune rejection
Protect the fetus from pathogens
147
Prevent maternal immune rejection
maintains the separation between maternal and fetal blood to prevent the mother’s immune cells from
detecting the fetal tissues and potentially rejecting them as a foreign body
- there are changes to the maternal immune system that lead to immune tolerance
148
Protect the fetus from pathogens
shields the fetus from potential pathogens or toxins that may have
accessed the maternal circulation or the uterine cavity via the vaginal canal (pathogen can pass it though)
149
potential mechanisms of Protect the fetus from pathogens
is the direct infection of trophoblast cells, which then allows the
pathogen to spread to the fetus.
150
after ovulation
corpus luteum will secrete estrogen and progesterone,
the sex hormones that promote the remodeling of the uterine lining in preparation for pregnancy,
among other physical change
151
when will the corpus luteum secrete hormornes until
around 10 days after ovulation and will undergo involution
152
what triggers menstruation
the declining levels of hormones however with pregnancy the implanting embryo stimulates the survival of the corpus luteum by human chorionic gonadotropin (hCG)
153
Human chorionic gonadotropin (h C G) what produces it
produced by trophoblast cells, especially
syncytiotrophoblasts, shortly after they develop and invade the decidua
154
main function of h C G
is to substitute the effects of LH in supporting the survival and function of the corpus luteum, inducing
the corpus luteum to grow and continue to produce progesterone and estrogen.
155
how do pregnancy tests work
measuring the h C G hormone levels in urine. H C G is only synthesized by the body after
implantation, once the trophoblast cells have differentiated and developed sufficiently to begin
producing hormons
156
when is a pregnancy test most accurate
after the first missed menstrual cycle to ensure there are detectable levels of h C G, if present.
157
First Trimester - sex hormones
Embryo implantation occurs around 5-6 days after ovulation
- The corpus luteum begins to degrade
around 10 days after ovulation.
- H C G must appear by the 10th day post ovulation (4 days after
implantation) to stop the corpus luteum from degrading.
158
Second Trimester sex hormones
- After the 12th week of development, the placenta starts producing enough progesterone and estrogen
to sustain the remainder of the pregnancy.
- The production of h C G by the embryo decreases and the
corpus luteum degrades between the 13th and 17th week of gestation.
159
Third Trimester sex hormoens
Once the placenta takes over the production of progesterone and estrogen, the levels of estrogen and
progesterone increase steadily until the end of the pregnancy.
160
pregnancy and anterior pituitary gland
under goes a two-to-three fold enlargement
- alothough progesterone and estrogen supress FSH and LH throughout pregnancy, the production of other pituitary hormones is enhances
161
what hormones are enhanced during pregnancy
corticotropin (ACTH), thyrotropin (TSH) and prolactin (PRL)
162
Adrenal Cortex
Adrenocorticotropic hormone (A C T H)
163
Adrenocorticotropic hormone (A C T H)
involved in the stress response, so it regulates a wide
range of functions from appetite suppression to feelings of anxiety.
- responsible for determining the length of gestation and the timing of parturition.
Some is produced by the placenta as well.
164
Thyroid Gland
Thyroid-stimulating hormone or thyrotropin (T S H)
165
Thyroid-stimulating hormone or thyrotropin (T S H)
- increases the production of thyroid hormones by 40 to 100 percent
- changes increase maternal metabolic rate, to meet the nutrient demands of the fetus. Also, maternal thyroxine can cross the placenta and is required by the fetus in the first 12 weeks of
development, to maintain its thyroid function.
166
Mammary Glands
Prolactin (P R L)
167
Prolactin (P R L)
- stimulates the mammary glands to produce milk
168
Prolactin (P R L) Early in pregnancy
P R L stimulates the proliferation of glandular epithelial cells and presecretory
alveolar cells of the breast, causing the breasts to grow
169
Prolactin (P R L) After birth
is released in pulsatile bursts in response to suckling by the baby
170
Ovary hormones
- F S H and L H are inhibited for the duration of the pregnancy, thus preventing ovulation from
happening during this time
171
Ovary hormones after birth
- takes between 2 months to a year for the hormonal cycle to be restored to its normal state and begin the cycle of ovulation
172
mammary gland changes
- estrogen, progesterone, and prolactin, the breasts increase in size throughout pregnancy.
- Vascular supply to the breasts increases
- The ducts, alveoli, and mammary epithelium undergo hyperplasia in preparation for lactation
173
when does the first milk (colostrum) appear
in the alveoli of the acinar glands as early as the second trimester
174
when is milk inhibited til
after birth
175
uterus changes during pregnancy
- endometrial layer is transformed by decidualization
- Uteroplacental blood flow doubles by mid-gestation, due to spiral artery remodeling
- stretched to accommodate the fetus, placenta, and amniotic fluid,
176
what does stretching of the uterus cause
hypertrophy of the muscle cells of the myometrial layer
177
volume of uterus after pregnancy
uterus has increased 500 to 1000 times
178
cervix changes during pregnancy
- cervix softens due to undergoing connective tissue remodeling
- Cervical glands double in number and create a mucus plug, that acts as a barrier to protect the uterine
contents from infections. This plug is expelled shortly before delivery
179
connective tissue remodeling
softing of cervix
- needed for maintenance of structural integrity to carry the pregnancy to term, dilation during delivery and repair following parturition
180
physiological changes each bodily system undergoes in
response to pregnancy
- Circulatory System
-Metabolic System
-Musculoskeletal System
-Immune System
-Respiratory System
181
Circulatory System changes with pregnancy
- Cardiac output increases as much
as 50% by mid-pregnancy, as a result of an increase in heart rate and stroke volume
- increase in blood volume and red blood cell mass
182
what does increase blood flow do to the placenta
causes a drop in total vascular resistance
183
when does cardiovascular changes go back to normla
as early as 2 weeks postpartum
184
when does metabolic needs of the fetus peak
in the third trimester, which is the phase of greatest growth
185
maternal metabolism in early pregnancy
largely anabolic, storing nutrients for the upcoming demands
186
maternal metabolism late gestation
becomes largely catabolic, directing
nutrients to the rapidly growing fetus
187
when does insulin resistance develop
in early pregnancy
188
why does insulin resistance develop
to limit maternal glucose consumption and direct most of it to the fetus
189
late pregnancy, maternal adipose tissue
releases fatty acids for use by the liver and muscle. The liver
metabolizes fatty acids to make ketones that are usable by the brain, muscle, and fetus, but uses
glycerol and amino acids to synthesize glucose for the fetus
190
what does the liver do
the liver metabolizes fatty acids to make ketones that are usable by the brain, muscle, and fetus, but uses
glycerol and amino acids to synthesize glucose for the fetus
191
Anabolic
involving metabolic pathways that build new molecules out of the products of catabolism,
which are used to build and maintain cellular structures
192
Catabolic
involving metabolic pathways that breakdown molecules into usable forms; energy is either
stored in energy molecules or released as heat.
193
how much weight does a mother gain in pregnancy
10-15 k g of weight
- 3 k g of the weight gain is the fetus, 1.8 k g is amniotic fluid and fetal membranes,1 k g is the overgrown uterus, 1 k g is in the breasts, and 1.3
k g can be attributed to fat accumulation.
194
weight gain causes what
- shift in the body’s center of gravity, which requires a realignment of the
spinal curvature and pelvic tilt that leads to lumbar lordosis.
- increased joint mobility due to ligamentous laxity, particularly of the sacroiliac joints, which
will facilitate delivery later on
195
Stretching of the abdominal ligaments results
diastasis recti.
196
Lumbar Lordosis:
Excessive inward curvature of the spine, in this case, the lumbar region.
197
Diastasis Recti
The separation of the two sides of the rectus abdominis muscle
198
how does the body ensure fetal tolerance
trophoblast cells produce factors that suppress the maternal immune
response
199
immune tolerance
prevents rejection of paternal antigens expressed by the fetus, but
it also changes disease susceptibility, making women more susceptible to infectious diseases and
less susceptible to inflammatory diseases
200
are immune cells key in placenta development
yes
201
during implantation immune cells
e decidua is populated by a
large variety of immune cells
202
first trimester immune cells
70% of these cells are uterine (or decidual) natural killer cells (u N K or d N K).
203
uterine (or decidual)
natural killer cells (u N K or d N K)
secrete factors that promote early vascular remodelling and help establish fetal tolerance-
- critical for the establishment of
pregnancy. Their numbers begin to decline at mid-pregnancy, reaching normal levels at term.
204
does oxygen consumption increase and why with pregnancy
With increased metabolic and cardiac needs, oxygen requirements also increases significantly during
pregnancy
- increases about 20 percent through pregnancy, and 40-60 percent
during labour.
205
The higher number of red blood cells increases
the mother’s oxygen-carrying capacity.
206
Around the 6th month of gestation begins to exert increasing pressure on the mothers diaphragm
This reduces lung capacity and causes an increase in minute ventilation
207
what is paturition
the process by which childbirth occurs, also known as labour and delivery. Vaginal birth is
the natural and most common way for childbirth to occur, and proceeds in three stages
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what are the 3 stages of parturition
Stage 1: Onset of labour
Stage 2: Active Labour
Stage 3: Delivery of the Placenta
Stage 4: Immediate Postpartum
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Stage 1: Onset of labour
stage preceding labour
- characterized by the beginning of regular uterine contractions
- Uterine contractions are controlled by a positive
feedback loop known as the Ferguson reflex
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what does the stage 1: onset of labour include
the latent phase and the active phase
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step 1 in positive feedback reflex of parturition (ferguson reflex)
The pressure of the fetal head on the cervix causes stretching of the mother’s cervix and also causes
stretching of the uterine walls.
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step 2 in positive feedback reflex of parturition (ferguson reflex)
In response to the stretching, nerve impulses are sent to the hypothalamus in the brain.
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Step 3 in positive feedback reflex of parturition (ferguson reflex)
The hypothalamus signals the posterior pituitary to release Oxytocin.
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Step 4 in positive feedback reflex of parturition (ferguson reflex)
- The oxytocin released from the pituitary travels through the bloodstream to the muscular walls of the uterus, and causes smooth muscle contractions of the myometrium in the uterus.
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what does myometrial contractions increase
cervical dilation, further stimulating release of oxytocin and hence the cycle continues. This process is also known as cervical ripening, which allows the baby to fit through the
cervix
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Latent Phase:
the time of the onset of labour when the mother starts experiencing regular contractions
until the cervix is dilated to 3cm.
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Active Phase
the contractions become increasingly intense - more frequent, longer. Strong this continues from 3 cm until the cervix is fully dilated to 10 cm.
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Symptoms for the onset of labour vary between women, but can include
Lightening,
Experiencing regular uterine contractions
The amniotic sac may break
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Lightening,
the baby moves down from the rib cage and sits lower in the pelvis
- Pregnant
women may find breathing easier since lungs have more room for expansion, although this puts
pressure on the bladder.
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regular uterine contractions
less than 10 minutes apart, accompanied by cervical
effacement and dilation.
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"water break".
The amniotic sac may break at this point, releasing the amniotic fluid,
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stage 2 : active labour
- the cervix progressively dilates until it is fully dilated to 10 c m
- process of dilation and effacement of the cervix can last between 8 to 20 hours
- increasing pressure on the cervix stimulates a positive feedback cycle in
which the pressure on the cervix causes the release of oxytocin, which stimulates uterine contractions
that then further increase pressure on the cervix.
- expulsion and delivery of the baby.
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stage 3 : delivery of the placenta
- shortest stage that starts immediately after fetal birth.
- range anywhere between 5 to 30 minutes
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to help deliver the placenta,
the physician will put pressure on the mother’s abdomen, helping
detach the placenta from the uterus.
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Signs that indicate placental separation
firmer uterine fundus, a sudden gush of blood from the vagina, a lengthening of the umbilical cord, and a rise of the uterus into the abdomen
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stage 4 : immediate postpartum
- clinically defined as the hour or two after delivery when the tone of the
uterus is reestablished
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mother during immediate postpartum
- monitored closely
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risk in immediate postpartum
postpartum hemorrhage, which can happen if the uterus does not contract properly following
delivery. Uterine massage is commonly used to help the uterus contract.
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immediae postpartum ; mammary glands
contain colostrum, which is the first form of breastmilk present after delivery
- It contains immune cells and nutrients, which will provide the newborn with basic immunity within the first few hours after being born.
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term postpartum is also used to refer to
following 6 weeks after birth, also known as the
puerperium. During this time, the mother undergoes physical recovery
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infant coated in a white
yellowish substance
vernix caseosa, and serves to protect their skin from the exposure to
amniotic fluid in the womb.
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complication of parturition
About 4% of women will have
a breech birth, when the baby is delivered bottom first rather than head first. If the baby is in breech position, the practitioner may order an external cephalic version to turn the baby into the appropriate position for birthing.
- labour can be medically induced or a
cesarean section
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External cephalic version
A procedure to turn the fetus from the breech to cephalic presentation
before labour begins.
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Augmentation:
- process of stimulating the uterus to increase the frequency, duration and, intensity of contractions.
- commonly used to treat delayed labour when uterine contractions are
assessed to be insufficiently strong or inappropriately coordinated to dilate the cervix.
traditionally performed with the use of intravenous oxytocin infusion and/or
artificial rupture of amniotic membrane.
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A pregnancy complication
any health problem caused by pregnancy or occurring during the course of pregnancy that affects the wellbeing of the mother, the fetus, or both.
- can arise at anypoint
- can be caused by maternal or fetal origin
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The severity and outcome of the complication
will depend on the timing of onset (pre-pregnancy, first,
second or third trimester, or postnatal), and the causes (genetic anomaly, placental abnormality, etc
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do a majority of pregnancy complication involve
some kind of disruption to placental function, which affects fetal growth and development
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First Trimester complications
- associated with disruptions in the
process of implantation or early embryo development
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example of why complication in first trimester
if the mother has a preexisting condition (e.g. hypertension, diabetes), it will usually increase the risk of developing a pregnancy complication or will compound with any pregnancy issues that may arise later. However, embryo or fetal abnormalities can also disrupt the process.
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example of a complication in first trimester
- is the loss of an embryo or fetus before the 20th week of
gestation
-
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when do miscarriages occur
most often as natural response to the presence of an abnormality, to prevent a prevent unhealthy pregnancy moving
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In about two-thirds of early pregnancy failures
there is anatomical evidence of defective placentation featuring a thinner and fragmented trophoblast shell and reduced cytotrophoblast invasion of the endometrium.
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Defective placentation:
Abnormal and/or insufficient development of the placenta.
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anembryonic pregnancy
condition where the embryo does not develop, leaving only the gestational sac. The body typically eliminates the gestational sac naturally, resulting in a clinical miscarriage, even if no embryo is present
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what cause compilations during pregnancy in second trimester
- in the absence of an external cause, such as viral infection or toxin disorders that happen in second are often because of issue initiand in the first trimester
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Preeclampsia
- most severe hypertensive disorder of pregnancy, characterized by high blood pressure and proteinuria (excess presence of protein in urine) after 20 weeks of gestation
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what is the main danger of preeclampsia
it can evolve into eclampsia
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eclampsia
onset of seizures in a woman with
preeclampsia, and is considered a medical emergency
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cause of preeclampsia
unknown but it is crealy associated with impaired placentation in the first trimester
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what happens in the process of placentation with preeclampsia
- the trophoblast invasion and remodeling of the uterine arteries is impaired, resulting in arteries that are smaller
- as the pregnancy continues this causes inadequate placental perfusion resulting in placental ischemia
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placental ischemia
in insufficient or inconsistent oxygen and nutrient flow to the placental bed
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what does the immune system think of placental ischemia
a stress signal, leading to local production of inflammatory signals that will induce changes to the cardiovascular profile of the mother
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complication of third trimester
- challenging as clinicans need a balance the concern for maternal well-being with the consequences of a premature delivery
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whats the earlies a baby can survive
22 weeks of gestation 50% chance of surivial
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Antepartum hemorrhage
- defined as bleeding that occurs after the twentieth week of gestation but
before birth and it is considered a medical emergency.
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Antepartum hemorrhage what causes it
caused by abnormalities with the
anatomy of the placenta
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maternal and fetal life-threatening causes of antepartum
bleeding
abruptio placenta and placenta previa.
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Antepartum hemorrhage Management
depend on the cause of bleeding, but generally includes delaying
delivery or inducing delivery if the bleeding is life threatening to the mother.
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Abruptio Placenta
premature separation of the placenta from the uterus,
resulting in either a revealed or concealed internal hemorrhage
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Placenta Previa
when the placenta partially or totally covers the mother's cervix,
obstructing the birthing canal and preventing normal delivery
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can pregnancy complication cause risks to fetus
yes and can affect long term health
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Intrauterine growth restriction (I U G R)
- significant reduction in fetal growth during gestation
- a result of placental insufficiency
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I U G R infants
- have a birth weight
below the 10th percentile for their gestational age
- linked to poorer health outcomes
later in adult life
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health consequences of IUGR
- depend on the cause and extent of growth restriction
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potential factors that can lead to I U G R.
Preeclampsia is a condition associated and results in I U G R about 30% of
the time.
- Impaired fetal growth is associated with a higher risk of fetal morbidities, such as preterm birth and mortality in rare case
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preterm birth
- h occurs before 37 weeks of gestation.
- affects 5-18% of all pregnancies.
-
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what are the cause of neonatal death
Preterm births
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what are the second leading cause of infant death below age 5
preterm birth
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spontaneous onset of premature labour
two-thirds of preterm briths occur from this
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one-third of preterm births
are medically induced because of maternal or fetal complications
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stress and preterm infants
- they are exposed to variety of stressors and environemental conditions, in utero and after birth
- these stressors can cause permanent changes in the organ system development
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who are more likely to develop chronic disorders in adult life.
preterm babies and those who suffered I U G R
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chronic disorders in adult life
hypertension, coronary artery disease, and diabetes, demonstrating how the fetal environment can
even impact the development of diseases later in life
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why we see an increase in preterm births in developed countries from 1990-2010
- Changing Pregnancy Demographics
- Induced Preterm Births Improve Fetal Mortality Rates
- reporting of medically induced preterm births
- the case of a complex relationship
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Changing Pregnancy Demographics
- The widespread availability of effective contraception, and other social changes, have led to women in
developed countries having children later in life
- , even women who
experience fertility issues are able to conceive by using assistive reproductive technologies such as I V
F.
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Induced Preterm Births Improve Fetal Mortality Rates
- The induction of a preterm birth ultimately leads to a lower rate of stillbirths and neonatal morbidity
- studies that have noted an association between the rising rate of
Cesarean (C) sections (done both preterm and full term), with falling perinatal morbidity rates.
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Reporting of Medically Induced Preterm Births
The rise in preterm births can also be attributed to the increased registration and documentation of preterm births. Rather than a genuine change in preterm births, this simply reflects improved reporting of such cases.
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The Case of a Complex Relationship
important to understand that there is a complex relationship between the changes seen in perinatal care and changing pregnancy demographics.
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fetal screening
advances in diagnosis and treatment procedures have decreased maternal and neonatal morbidity and mortality by increasing the early detection of maternal and fetal problems
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information from the prenancy tests and screenign tests
allow both medical practitioners and parents to make informed decisions
about any potential interventions or the necessary preparations for a negative outcome or for the
arrival of a baby with special medical needs
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when do most tests for pregnancy occur
in the first trimester, in accordance with the fact that this is the most sensitive developmental time for both mother and fetus
