00:00
hello and welcome to this app go basic
00:02
science objective video about maternal
00:05
fetal physiology after watching this
00:08
video you should be able to describe the
00:11
maternal endocrine changes that provide
00:13
an adaptive environment for the
00:15
developing fetus identify the
00:17
physiologic changes of pregnancy that
00:19
allow the mother to tolerate a symbiotic
00:21
relationship and explain how the
00:24
physiologic adaptation of the fetus
00:26
and placenta allow the fetus to thrive
00:29
hey Jamie how are you doing
00:31
isn’t your duty coming up soon oh I’m
00:35
exhausted this baby is taken over every
00:37
single organ system in my body I don’t
00:41
think it’s taking over every single
00:42
organ system are you kidding me were you
00:45
not listening to any of the ob gene
00:47
lectures the fetus is a master parasite
00:50
it’s able to use its influence to
00:52
manipulate every organ system and
00:54
endocrine pathway okay fine
00:57
but I bet I can find one organ system
00:59
that is not manipulated I know that
01:02
ovarian hormones are affected but it’s
01:04
not like the entire endocrine system is
01:06
being manipulated what about the
01:08
pancreas or the tiny parathyroids
01:11
nice try Sam
01:13
almost every endocrine hormones is
01:15
altered in pregnancy some due to true
01:17
physiologic changes and others due to
01:19
increased liver production of finding
01:21
globulin or decreased serum albumin due
01:23
to the delusional effects of volume
01:25
expansion maternal endocrine changes are
01:28
also mediated by increased renal
01:29
lamellar filtration decreased hepatic
01:32
clearance for metabolic clearance of
01:34
hormones by the placenta there is not a
01:36
gland that is spared the pituitary gland
01:38
increases in size mainly due to lactate
01:41
Rauf hyperplasia stimulated by high
01:42
estrogen levels prolactin progressively
01:45
increases during gestation in
01:46
preparation for lactation while FSH LH
01:49
are almost undetectable the thyroid
01:51
gland enlarges in the first trimester
01:52
the HCG and TSH alpha subunits are very
01:56
similar
01:56
thus elevated HCG has spiro trophic
01:59
effect total serum thyroxine increases
02:02
due to increased production of thyroid
02:04
binding globulin however free t3 and t4
02:07
remain unchanged and those darling tiny
02:11
parathyroid glands undergo hyperplasia
02:13
to increase hormone production and meet
02:15
the calcium needs a fetal bone formation
02:17
the pancreas yeah that too it undergoes
02:20
hyperplasia of insulin-secreting beta
02:22
cells insulin is responsible for
02:24
intracellular transport of nutrients but
02:26
does not itself cross the placenta
02:28
insulin regulates the availability of
02:30
metabolites for placental transport even
02:32
the adrenal cortex is not spared from
02:35
fetal influence the total serum cortisol
02:37
is increased mostly due to an estrogen
02:39
stimulated increase in cortisol binding
02:41
globulin or CBG increased cortisol may
02:44
also contribute to insulin resistance
02:45
and development of striae my least
02:48
favorite
02:48
those darn stretch marks okay Jamie you
02:53
win this time
02:55
let’s pause think and apply when
02:57
evaluating a pregnant patient what
03:00
happens if a physician fails to
03:01
recognize normal pregnancy related
03:04
changes in endocrine function tests this
03:08
may lead to unnecessary testing and
03:10
therapies that are potentially harmful
03:12
to the fetus and the mother oh my feet
03:18
feel so swollen this state of chronic
03:20
volume overload with active sodium and
03:22
water retention is getting old quick huh
03:25
I guess the changes in the
03:26
renin-angiotensin system and ozma
03:28
regulation will come to an end soon
03:30
enough Jamie what about the
03:33
cardiovascular system what yeah the
03:38
cardiovascular system is minimally
03:40
affected by the fetus are you kidding me
03:43
my cardiovascular system is so tightly
03:45
influenced by my fetus first my ribcage
03:47
changes and my elevated diaphragm has
03:50
rotated my heart slightly there’s an
03:51
eccentric hypertrophy of the heart
03:53
resulting from expanded blood volume and
03:55
increased afterload the cardiac output
03:57
increased in early gestation with a peak
03:59
increase of 30 to 50 percent this is a
04:02
result of increased blood volume heart
04:04
rate and stroke volume blood pressure
04:06
and systemic vascular resistance
04:07
decreased with mid pregnancy nadir due
04:10
to progesterone mediated smooth muscle
04:12
relaxation and relative unresponsiveness
04:14
to angiotensin ii and norepinephrine in
04:17
pregnancy
04:18
there is also an increased risk of
04:20
pulmonary edema due to the combined
04:22
effects of falling systemic and
04:23
pulmonary vascular resistance and
04:25
decreased colloid osmotic pressure and
04:27
pregnancy cardiac function crescendos in
04:30
labor and immediately postpartum and
04:32
must manage the auto transfusion that
04:34
occurs after delivery of the baby in
04:35
placenta as the uterus rapidly in
04:38
volutes you’re okay fine I guess you’re
04:41
right aha see are you scared me what are
04:47
you doing back there
04:48
a hematologic system i win Oh Sam I
04:53
can’t believe how much you forgot from
04:54
year one the hematologic system is 100%
04:57
influenced by the fetus in fact all
04:59
components of blood plasma platelets
05:01
white blood cells and red blood cells
05:03
are altered in pregnancy these changes
05:06
are considered protective against
05:07
possible hemorrhage the total blood
05:09
volume increases by 40 to 50 percent in
05:11
pregnancy one there’s an increase in
05:14
plasma volume at 6 weeks with a mismatch
05:16
in red cell volume that leads to a
05:18
physiologic and anemia nattering at 28
05:21
to 34 weeks to a three-fold increase in
05:24
erythropoietin causes a wreath Royd
05:26
hyperplasia in bone marrow to help
05:29
increase red blood cell mass 3 platelet
05:32
counts decrease partly due to chemo
05:35
delusion and partly due to an increased
05:37
destruction and aggregate II for white
05:40
blood cells particularly neutrophils and
05:43
granulocytes increase due to elevated
05:45
estrogen and cortisol levels in
05:47
pregnancy
05:47
finally a most concerning there’s a
05:50
five-fold increase risk for
05:52
thromboembolism due to estrogen
05:54
stimulation of the liver to produce pro
05:56
coagulants and there is a decrease of
05:58
natural coagulation inhibitors and
06:00
fibrinolytic activity so nice try Sam
06:03
but you’re gonna have to work harder to
06:05
find something this baby is not trying
06:06
to manipulate ah this is getting so hard
06:09
now surprise from your spidey friend
06:12
pulmonary there is no way that kiddo can
06:16
get near your lungs are you kidding me
06:19
do you hear me right now my elevated
06:21
diaphragm from the baby pushing up
06:22
decreases my total lung capacity and
06:24
functional residual capacity increased
06:27
progesterone drives an increase in
06:29
new ventilation and chronic
06:30
hyperventilation resulting in an
06:32
increased pao2 and decreased paco2
06:36
consequently I have a chronic
06:38
respiratory alkalosis that is partially
06:42
compensated for by an increased renal
06:44
excretion of bicarbonate although this
06:46
mild dyspnea is compatible with daily
06:49
activities it does increase inspiratory
06:51
muscle effort so no Sam I still win this
06:55
baby is manipulating everything now if
06:58
you will excuse me I have to find a
07:00
bathroom and before you even try the
07:02
renal system is definitely under siege
07:04
progesterone causes smooth muscle
07:06
relaxation which dilates the ureters in
07:09
renal pelvis as they empty more slowly
07:11
renal plasma flow and glomerular
07:13
filtration rate increase leading to
07:15
increased clearance of creatinine
07:16
glucose urinary protein and albumin and
07:19
my favorite is a decreased bladder
07:22
capacity due to an enlarged uterus okay
07:26
on that note Spidy we’ll see you soon Oh
07:29
in the bathroom is at the top of the
07:30
stairs on the left hey Sam thanks for
07:35
inviting me to join you for dinner I am
07:37
starving Jamie are you able to eat all
07:41
that at once I just assumed with the
07:43
increase in progesterone you have a
07:45
relaxed gastro esophageal sphincter and
07:47
a wicked reflux especially with the
07:50
uterus causing gastric compression
07:52
thanks Sam you are right sometimes I do
07:55
get reflux but that’s not even the half
07:58
of it
07:58
progesterone decreases intestinal
08:00
motility and gastric emptying
08:02
progesterone also slows gall bladder
08:05
emptying which leads to increased
08:06
biliary cholesterol saturation and
08:08
increased risk for gallstone production
08:10
but the worst is the increase in port of
08:13
venous pressure that leads to terrible
08:15
hemorrhoids well at least I have a
08:17
reduced risk for peptic ulcer disease
08:19
thankfully an increase in placental
08:22
histamines leads to increase maternal
08:24
gastric mucin production which in turn
08:26
protects my gastric mucosa immune
08:28
changes also help increase tolerance of
08:30
h pylori you’re right Jamie the baby has
08:33
influenced almost every body system but
08:36
remember the baby has to make lots of
08:38
adaptations to successfully live with
08:40
you two
08:41
the first and most important is dealing
08:43
with your immune system the fetus and
08:46
the placenta produce estrogen
08:47
progesterone human chorionic
08:49
gonadotropin and human placental lacta
08:52
j’en which may allow for maternal
08:54
tolerance of the antigenically different
08:56
fetus progesterone also acts
08:59
synergistically with relaxin to promote
09:01
uterine quiescence and inhibits t-cell
09:04
mediated allograft rejection this may
09:06
aid in uterine tolerance of the
09:08
trophoblastic tissue the interference of
09:11
maternal and fetal vasculature in the
09:13
placental bed also blocks or masks
09:15
antibodies and as such only IgG can
09:19
cross the placenta the benefit of
09:22
allowing for passage of IgG is to
09:24
provide passive immunity to the fetus
09:26
and early neonate this baby is certainly
09:30
well protected and well fed growing
09:32
bigger and bigger every day well I hope
09:35
so all that food and oxygen you’re
09:37
consuming is doing its job glucose
09:40
derived from the placenta is the main
09:42
substrate for fetal oxidative metabolism
09:44
especially in the fetal brain to produce
09:46
energy and tissue growth other
09:49
substrates also include lactate and
09:50
amino acids fat tissue growth is a
09:53
result of conversion of carbohydrates to
09:55
lipids and placental fatty acid uptake
09:58
and uses about 20% of fetal oxygen
10:02
consumption higher fetal insulin levels
10:05
increased fetal body heart and liver
10:07
weights this is exacerbated in diabetic
10:09
mothers with poorly controlled glucose
10:11
levels corticosteroids too are important
10:14
to fetal growth in organ maturation with
10:17
fetal levels increased at par tradition
10:19
however fetal growth actually slows near
10:22
parturition perhaps through suppression
10:24
of fetal igf-1 binding proteins for
10:27
igf-1 increased near-term and high
10:30
levels also correlate with utero
10:32
placental insufficiency finally let’s
10:35
not forget all those cardiovascular
10:36
changes the fetus must undertake you
10:39
remember that aapko educational video
10:41
number 8 that we saw during first year
10:43
right
10:44
let’s pause thinking apply why does it
10:48
feed a seemly tolerate significant
10:49
maternal hypoxemia as a result of
10:51
maternal pneumonia or pulmonary edema
10:54
the fetus does not experience problems
10:57
as readily because of compensatory
10:59
mechanisms including increased cardiac
11:02
output increase fh are increased oxygen
11:06
carrying capacity of fetal hemoglobin
11:08
increased RBC and anatomical shunts yeah
11:13
I remember that video it is amazing how
11:15
there’s almost a total rerouting of the
11:17
circulation with the first breath and
11:19
these compensatory mechanisms are able
11:22
to maintain a state of fetal aerobic
11:24
metabolism even though I swear like I am
11:26
constantly sucking win these days see
11:29
even though you feel like the baby is
11:31
trying to manipulate all of your system
11:33
for its benefit the fetus has to make
11:35
several adaptations to survive the
11:37
intrauterine environment maybe it’s more
11:40
of a symbiotic relationship rather than
11:42
a parasitic one yeah okay you’re right
11:46
it is a pretty amazing system that
11:48
allows the fetus to grow and develop
11:49
thanks for reminding me
11:51
sometimes it is easy to get caught up in
11:53
all the discomfort
11:55
this concludes this aapko basic science
11:57
objective video about maternal fetal
11:59
physiology you should be able to
12:02
describe the maternal endocrine changes
12:04
that provide an adaptive environment for
12:07
the developing fetus identify the
12:09
physiologic changes of pregnancy that
12:11
allow the mother to tolerate a symbiotic
12:13
relationship and explain how the
12:16
physiologic adaptation of the fetus and
12:18
placenta allow the fetus to thrive
12:21
thanks for watching

00:00
Welcome to this talk
00:01
on the physiological changes
00:03
in pregnancy.
00:05
Pregnancy is associated
00:06
with a number
00:07
of profound physiological and
00:09
anatomical changes
00:10
that both assist
00:11
in fetal survival as well as
00:13
prepare the mother for delivery.
00:15
And it’s important to know what
00:16
the parameters
00:17
of these normal changes
00:18
are in order to diagnose
00:20
and manage
00:21
other medical problems that may
00:22
occur in pregnancy.
00:23

00:26
By the end of this lecture,
00:28
you’ll be able to describe
00:29
the physiological changes
00:31
in pregnancy
00:31
in terms
00:32
of the cardiovascular,
00:34
respiratory, hematological,
00:36
and gastrointestinal systems.
00:38
You’ll also understand
00:39
the impact of these changes
00:41
on the management
00:41
of the pregnant patient.
00:42

00:46
Pregnancy induces
00:47
profound changes in the woman’s
00:48
anatomy and physiology.
00:50
The female body begins to adapt
00:52
to the growing demands
00:53
of the fetus
00:54
even before pregnancy may be
00:55
clinically detected.
00:57
These complex areas
00:59
of physiological an
01:00
anatomical changes are primarily
01:02
hormonally mediated
01:03
and affect every system
01:04
of the body.
01:06
The primary goals are
01:07
to optimize maternal conditions
01:09
for fetal growth,
01:10
prepare for delivery,
01:12
and to develop the mother’s
01:13
breast for the production
01:14
of milk.
01:14

01:17
First, let’s take a look
01:18
at the cardiovascular changes
01:20
in pregnancy.
01:22
The cardiac output increases
01:23
as a function of two changes
01:25
in how the heart works.
01:27
One, there’s an increase
01:28
in stroke volume,
01:29
or the blood of volume
01:30
pumped out of the heart
01:31
per beat.
01:33
This is predominantly
01:34
as a result of increased blood
01:35
volume.
01:37
Two, there’s an increase
01:38
in the resting heart rate.
01:40
The heart rate is about 15 beats
01:41
per minute
01:42
higher
01:42
than in non-pregnant women.
01:44
As you remember,
01:45
the cardiac output
01:46
is the product of the stroke
01:47
volume and the heart rate.
01:49
Thus, this results
01:50
in the steady rise
01:51
in cardiac output, which rises
01:53
about 50%
01:54
above the pre-pregnancy cardiac
01:56
output.
01:57
The blood pressure, however,
01:59
as you can see from the graph,
02:00
takes a slight dip
02:01
at the beginning,
02:02
and then slowly rises.
02:04
Thus, it’s relatively stable.
02:06
Thus, with a stable BP
02:08
and an increase
02:09
in cardiac output, there must be
02:10
a decrease in systemic vascular
02:12
resistance.
02:13

02:16
Another change you may see
02:17
during the later stages
02:18
of pregnancy
02:19
is aortocaval compression,
02:21
or compression of both
02:23
the inferior vena cava
02:24
and the lower aorta
02:26
when the patient is supine.
02:28
This leads to a reduction
02:29
in venous return,
02:30
and thus, a fall
02:31
in cardiac pre-load The fall
02:33
in cardiac pre-load
02:34
may reduce cardiac output, which
02:37
may threaten perfusion.
02:40
Furthermore, compression
02:41
of the aorta
02:41
may lead to reduced perfusion
02:43
to the uterus and placenta, as
02:45
well as the kidneys.
02:46
It’s been shown
02:47
that during the last trimester,
02:49
maternal kidney function is
02:50
lower in the supine position
02:52
than when sitting or standing.
02:54
Fetal transplacental gas
02:56
exchange may also be affected,
02:58
due to decreased perfusion
02:59
to the placenta.
03:01
As a result, one should advise
03:03
women not to lie supine
03:05
during the later stages
03:06
of pregnancy.
03:06

03:10
The respiratory tract also
03:11
undergoes changes in response
03:12
to the maternal adaptation
03:14
to pregnancy.
03:15
Starting at the upper airways,
03:17
hormone-induced changes
03:18
to the mucosa vasculature
03:20
of the upper airways
03:21
leads to capillary engorgement,
03:23
congestion, and edema.
03:25
This may lead to nasal
03:26
stuffiness, and more
03:27
importantly,
03:28
difficulties with intubation
03:30
in the case
03:31
that emergent Cesarean sections
03:33
become necessary.
03:35
Minute ventilation rises 150%
03:36
at term, as you can see
03:38
in the graph on the right.
03:40
Progesterone, a known stimulant
03:41
of the respiratory drive,
03:43
gradually rises
03:44
throughout pregnancy.
03:45
And as such, it increases
03:46
sensitivity to carbon dioxide
03:49
such that increased CO2 elicits
03:51
an exaggerated respiratory
03:52
effort.
03:54
Progesterone is also known
03:55
to reduce airway resistance
03:56
by bronchial and tracheal
03:58
smooth muscle relaxation.
04:01
The functional
04:01
residual capacity, or FRC,
04:04
or the apnoeic reserve
04:06
of oxygen, decreases by 20%,
04:09
while the inspiratory capacity
04:11
remains the same.
04:12
This is partly
04:13
due to the mechanical effect
04:14
as the gravid uterus
04:15
causing elevation
04:16
of the diaphragm,
04:18
as well as the hormonal changes
04:19
associated with pregnancy.
04:21
As a result,
04:23
the pregnant patient
04:24
has a decreased ability
04:25
to tolerate periods of apnea.
04:29
Pregnant women also have
04:30
a marked increase
04:31
in their oxygen consumption
04:32
by up to 40% to 50%
04:34
over non-pregnancy levels.
04:36
This decreases
04:37
the partial pressure of carbon
04:39
dioxide and gives rise
04:40
to the chronic respiratory
04:41
alkalosis of pregnancy.
04:42

04:46
Now, let’s review some
04:47
of the hematological changes
04:48
in pregnancy.
04:49
As you can see from the graph,
04:51
blood volume increases by 50%
04:53
to 100%.
04:55
At the same time, red blood cell
04:56
counts only increase by 25%
04:58
to 40%.
05:00
This is why the hematocrit dips
05:02
down in this graph
05:03
because we have what’s
05:04
called physiological anemia
05:06
pregnancy, or dilutional anemia.
05:09
Elevated erythropoietin levels
05:10
increase total red blood cell
05:12
mass.
05:13
But hemoglobin concentrations
05:14
never reach pre-pregnancy levels
05:16
because you’re also having
05:18
an increase
05:18
in the overall plasma volume.
05:21
At the same time, the increased
05:23
red blood cell production also
05:24
creates a fall in serum iron,
05:26
while increasing the transferrin
05:28
and total iron-binding capacity.
05:31
As you can also see
05:32
from the graph, there’s also
05:34
a rise in the total white blood
05:35
cells during pregnancy.
05:38
Levels of some clotting factors,
05:40
including seven, eight, nine,
05:42
and 10, as well as fibrinogen,
05:45
increase during pregnancy,
05:47
while fibrinolytic activity
05:48
decreases.
05:50
This increases the risk
05:52
of thromboembolic disease.
05:54
The whole point
05:55
of this increased coagulability
05:56
though is to protect
05:57
from hemorrhage at delivery.
05:59
But it also puts the mother
06:01
at risk for getting DVTs
06:03
during pregnancy.
06:04

06:07
Finally, let’s complete
06:08
our overview
06:09
of the physiological changes
06:10
in pregnancy
06:11
by discussing briefly
06:12
the musculoskeletal, endocrine,
06:14
and renal changes in pregnancy.
06:17
In terms
06:17
of the musculoskeletal system,
06:19
there are elevated levels
06:20
of relaxin, which helps prepare
06:22
for delivery by softening
06:23
the cervix,
06:24
inhibiting uterine contractions,
06:26
and relaxing
06:27
the pubic symphysis.
06:29
This increased ligamentous
06:30
laxity, however, leads
06:31
to an increased risk
06:32
for back injury
06:33
and pubic symphysis dysfunction.
06:36
In terms
06:36
of the endocrine changes,
06:37
there are increased levels
06:38
of prolactin to prepare
06:40
for breastfeeding,
06:41
linearly increasing levels
06:43
of corticotropin releasing
06:44
hormone,
06:45
which is thought to be
06:46
a possible stimulant for labor,
06:48
and increased insulin production
06:50
in order to maintain blood sugar
06:51
levels.
06:52
Pregnancy is also associated
06:54
with increased insulin
06:55
resistance due to the secretion
06:57
of human placental oxygen.
06:59
Thus, the risk
06:59
for gestational diabetes
07:01
mellitus.
07:03
Renal changes include increase
07:04
urinary stasis.
07:06
This is due to smooth muscle
07:08
relaxation of the renal pelvis,
07:10
ureters, and bladder,
07:11
with an increase in bladder
07:12
capacity and residual urine
07:14
volume.
07:15
This urinary stasis leads
07:17
to an increased risk for UTIs.
07:20
There’s also increased
07:21
activation reno-angiontensin
07:23
system, which leads to increased
07:25
sodium retention and edema.