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2 Physiological andHormonal Changes During Pregnancy
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15
make up the functional residual capacity, which
consequently decreases. Also, the movement of
the diaphragm reduces the total lung capacity
by 5%.
As a way to compensate these changes, the
respiratory rate does not change, but the tidal volume (the volume of air that is displaced between
normal inhalation and exhalation) increases
markedly, from around 450mL in a non-pregnant
woman to 650mL during pregnancy. Similarly,
the inspiratory capacity rises from 2500 to
2750 mL at the expense of inspiratory reserve.
The vital capacity remains the same.
The pregnant woman has more air in movement and less air in reserve. This causes an
increase by 30–40% in minute ventilation.
All these adaptations are necessary because
the body and fetal requirements are near to
50mLO
per minute, 20% more than in a non-
2
pregnant woman.
These requirements come from the uterus,
which receives approximately 50% of this
increase, as well as the heart, kidneys, muscles,
and breast.
During labor, the needs increase by 40–60%
[1].
Changes in the tidal volume and the sensitivity
of central chemoreceptors to progesterone alter
the acid–base equilibrium due to the larger elimination of CO2. This respiratory alkalosis does not
lead to global alkalosis. Thankfully, the Bohr
effect compensates it by excreting more bicarbonate through the kidney. Therefore, the acid–
base maternal equilibrium remains normal [4].
2.2.4.3 Repercussion ofRespiratory
Changes
One of the typical symptoms in pregnant women
is dyspnea, which is caused by the decrease of
PCO2. This dyspnea may not affect the daily life
of the pregnant woman. If it does, other nonphysiological causes should be considered.
Commonly, the woman reports pseudoallergic or cold-like symptoms due to mucosal
hyperemia mediated by estrogen and progesterone [1].
2.2.5 Hematological System
Changes in the hematological system aim to
maximize oxygen transport to the fetus and to
minimize the deteriorated venous return and
childbirth-associated bleeding.
Most of them are mediated by estrogen and
progesterone.
2.2.5.1 Plasma
From the sixth week of pregnancy, the plasma
volume starts to rise. It reaches its maximum at
weeks 30–40. The increase is at least 50% more
plasma volume (more in multiple pregnancies).
This change tries to meet the metabolic
demands of the enlarging uterus and to nurture
the fetus and the placenta.
2.2.5.2 Red Blood Cells
The red blood cell volume needs to increase. It
grows by at least 450mL.For that reason, slight
erythroid hyperplasia is normal during
pregnancy.
2.2.5.3 Iron
Iron is necessary not only to increase red blood
cell volume but also for the fetus and to compensate the normal loss. The National Academy of
Sciences recommends supplementation with at
least 27mg of ferrous sulphate.
2.2.5.4 Hemoglobin andHematocrit
Due to plasma elevation, other blood components
such as hemoglobin and hematocrit must decrease
proportionally. For that reason, physiological
anemia may appear. Physiological anemia of
pregnancy takes place when hemoglobin is below
11mg/dL, and it may be corrected.
2.2.5.5 Leukocytes
Leukocyte count may vary during pregnancy.
The higher values can easily reach
12,000/L–15,000/L without pathological signicance. In the puerperium, values may be close to
25,000/L. The mechanism of this process is
unknown.
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T. Costas and M. Gomes-Ferreira
2.2.5.6 Platelets
In the same way as leukocytes, platelets may vary
during pregnancy. A decrease in platelets may be
related to gestational thrombocytopenia. Platelets
under 100,000/μL could compromise childbirth.
2.2.5.7 Coagulation
In total, 50% of all coagulation factors increase
during pregnancy. Especially, brinogen (factor
I) rises by 50%. Other factors that increase are
factors VII, VIII, IX, and X.
In contrast, proteins C and S reduce their
values.
2.2.5.8 Repercussion ofHematological
Changes
A greater amount of red blood cells allows better
oxygen distribution to the fetus and stimulates
the CO2 exchange between the fetus and the
mother.
However, these changes also create a state of
hypercoagulability in the pregnant woman. This
increases the thrombotic risk during pregnancy
and puerperium.
Also, the volumetric changes create a predisposition for edema. It usually appears in the forehead, legs, ankles, and feet [4].
A summary of the hematological system can
be seen in Table2.2.
2.2.6 Immune System
The immune system of the mother needs to tolerate a “foreign body” such as the fetus. Classically,
it is said that the key is in the placenta (it acts as
a barrier between the mother and the fetus).
Furthermore, the placenta secretes hormones
such as estrogen and progestogen, which stop the
immune response. The only immune molecule
that can pass through the placenta is IgG, so that
it can transfer passive immunization to the fetus.
The latest studies show that pregnancy is a
pro-inammatory and an anti-inammatory con-
Table 2.2 Summary of mechanisms, changes, functions of the changes, and main problems in the hematological
system
System Mechanism
Hematological
system
↑E: increase of estrogen levels
↑P: increase of progesterone levels
Plasma
Red blood
cells
Iron It may be
Hemoglobin
and
hematocrit
Leukocytes Unknown Increased None? Interpretation
Platelets Entrapment in
Coagulation
↑E, ↑P
↑E, ↑P
supplemented
↑E, ↑P
placenta
↑E, ↑P
Physiological
changes Function Main problems
Increased
plasma
Increased the
number of
red blood
cells
The need
grows
Decrease Allow plasma grows Hypercoagulability
None or
decreased
Increase: I,
VII, VIII, IX,
and X
Decrease:
protein C and
S
Meet the new
metabolic demands
Transport major
quantity of oxygen
Increasing of red
blood cells, it is
necessary for fetus
development
Avoid
hypercoagulability
state
Hypercoagulability
state
Hypercoagulability
state
Erythroid hyperplasia
It is not supplemented,
anemia could appear
state (if they do not
decrease
proportionally)
Gestational
thrombocytopenia
Bleedings
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dition, depending on its stage. During trophoblastic invasion it is an inammatory environment,
while in mid-pregnancy it is anti-inammatory.
Finally, childbirth is once again an inammatory
process [6, 7].
2.2.7 Metabolism
The fast development of uterus, placenta, and
particularly the fetus represent an increase in
energetic demands.
The maternal metabolic rate increases by
10–20% by the end of the pregnancy when compared with a non-pregnant woman.
2.2.7.1 Weight Gain
Weight gain is normal during gestation. The
average weight gain is between 12 and 18kg.
The most important part comes from the fetus,
uterus, placenta, and amniotic uid. Others components in weight gain are breast development,
fat deposition, and uid retention. This part is
variable in each woman.
2.2.7.2 Carbohydrate Metabolism
Pregnancy causes changes in carbohydrate
metabolism due to its diabetogenic effect: lower
insulin response, hyperinsulinemia, and
hyperglycemia.
These responses are due to human placental
lactogen (HPL) which is secreted by the placenta.
In addition, there is an effect from estrogen and
progesterone.
2.2.7.3 Fat Metabolism
All the fats, such as lipids and lipoproteins, are
elevated in the pregnant woman due to estrogen.
In the rst month, the concentration and stocking of lipid is prevalent; in the last period of gestation, lipolysis is the main process.
2.2.7.4 Protein Metabolism
At the end of pregnancy, the fetus and placenta
need more than 50% of the normal use of proteins. For that reason, the pregnant body tries to
stock proteins for this stage [1].
Summary of the metabolic changes can be
seen in Table2.3.
2.2.8 Endocrine System
Many gestational hormones cause changes in
maternal hormones due to their similar biochemical structure or because gestational hormones
stimulate maternal ones.
2.2.8.1 Thyroid
The thyroid gland increases its size moderately,
and many changes take place:
Table 2.3 Summary of metabolic changes during pregnancy
System Mechanism Physiological changes Function Main problems
Metabolic
changes
↑E: increase of estrogen levels
↑P: increase of progesterone levels
Weight gain Enlargement of the
Carbohydrate
metabolism
Fat metabolism
Protein
metabolism
uterus, placenta, fetus
and amniotic uid
↑E, ↑P, ↑HPL
↑E
↑E, ↑P
Increased between
12–18kg
Lower insulin
response
Hyperinsulinemia
Hyerglycemia
Lipids and
lipoproteins are
elevated
Increase Nurture of the
Fetus
enlargement
Nurture of the
fetus
Neurological
fetus
development
fetus
Fluid
retention
Lose weight
after
pregnancy
Gestational
diabetes
Weight gain
–
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T. Costas and M. Gomes-Ferreira
In the first trimester, human chorionic
gonadotropin (β-HCG) is elevated and it has
a similar activity to thyrotropin (stimulating
T4 secretion), temporarily rising the levels of
T4.
Moreover, estrogens stimulate the production
of TBG (thyroxine-binding protein), which in
turn stimulates T4 and T3 secretion. In spite of
that, gestation is a euthyroid state.
Other glands such as adrenal glands (there is
an increase in cortisol levels) and the pituitary
gland also change during pregnancy.
Hormones such as oxytocin or androgens are
subject to their own changes during pregnancy
[1].
2.2.9 Gastrointestinal System
The gastrointestinal system suffers the consequences of pregnancy. On the one hand, the
uterine enlargement displaces the gastrointestinal viscera, and the hormones affect the
mucosa and smooth muscle negatively. The
symptoms could range from slight aches to
severe pain.
2.2.9.1 Anatomical Changes
The most important change in this regard is the
lateral and upward displacement of all the gastrointestinal organs. This may not affect their size or
normal function but, in case of illnesses such as
appendicitis, it could be more difcult to identify
the structures involved.
The portal vein is bigger during pregnancy
due to the increase of the bloodstream.
2.2.9.2 Functional Changes
andRepercussion
Progesterone and estrogen have an effect on
smooth muscle and mucosal hyperemia. This
affects the gastrointestinal system down to the
lower esophageal sphincter, relaxing it. The
motility of the entire tract worsens, as does the
contractility of the gallbladder.
This causes an increase in reux and in the
prevalence of biliary colic and difcult
digestion.
Also, hyperemia causes gingival bleeding and,
together with uterine enlargement and the
increase in venous pressure, hemorrhoids are
more prevalent [4].
Nausea and vomiting are common symptoms
in pregnant women. The real cause is unknown,
although it could be related to raised progesterone and GcH.The severe end of the spectrum is
called hyperemesis gravidarum, and it can have
severe implications.
Constipation is a symptom of mechanical
obstruction caused by the uterus and the increased
absorption of water.
Itching, usually on hands and feet, is due to
the increase in biliary acid (mediated by estrogen) and cholestasis. It could be a severe condition that requires treatment or an early delivery
[1].
The main gastrointestinal problems are summarized in Table2.4.
Table 2.4 Main gastrointestinal problems
Problems of the gastrointestinal system
Problems Cause Comments
Nausea and
vomiting
Gingival
bleeding
Reux
Difcult
digestion
Itching
Cholestasis Worse
Constipation Mechanical
Hemorrhoids
↑E: increase in estrogen levels
↑P: increase in progesterone levels
Unknown
Probably raised
progesterone and
GcH
Hyperemia (↑E
and ↑P)
Relaxed LES (↑E
and ↑P)
Relaxation of
smooth muscle
(↑E and ↑P)
↑E and cholestasis
mechanism
contractibility of
gallbladder (↑E
and ↑P)
obstruction
Increased
absorption of
water
Hyperemia (↑E
and ↑P)
↑venous pressure
Severe
spectrum:
Hyperemesis
gravidarum
Severe
intrahepatic
cholestasis
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2.2.10 Urinary Tract
The urinary system experiences anatomical and
physiological changes in order to adapt to its new
role. The changes are promoted by hormones and
also due to uterine enlargement.
2.2.10.1 Anatomical Changes
The renal system has to manage a new volume
and new acid–base equilibrium due to respiratory
alkalosis. Therefore, the kidney cortex is swollen,
and the kidneys and the collecting system are
dilated. Due to these changes, the kidneys are
larger than in a non-pregnant woman.
This process is mediated by hormones and
also by the position of the enlarged uterus,
because while it grows, it rotates to the right and
affects more the right ureter than the left one.
Also, progesterone relaxes the smooth muscle
of the ureters and, consequently, they could also
be dilated.
The bladder is affected by the relaxation of the
smooth muscle, and the uterus is compressed and
becomes thinner (thus increasing residual volume), which reduces the capacity of the bladder
[4].
The pregnant woman is going to suffer
changes in the frequency and urge of urinating.
Also, urinary tract infections are more common
due to urinary stasis. Similarly, all types of bacteriuria must be treated because of the risk of
pyelonephritis.
2.2.10.2 Functional Changes
andRepercussion
Due to the new plasmatic volume, the kidney
ow increases, causing all the functional changes
in the kidney.
The kidney ow may increase by more than
75% compared with a non-pregnant woman. For
instance, the glomerular ltration rate may
increase by more than 50%.
The glomerular ltration is still functional,
and there is no loss of proteins during pregnancy
(if it appears, a disorder should be considered).
However, given the increase in glomerular ltration, it could be possible to analyze whether the
levels of glucose, B
within physiological range [4].
The entire renin-angiotensin-aldosterone system is altered during pregnancy. Renin is also
produced by the placenta (as well as by the
mother) and angiotensin is also produced by the
mother and the fetal liver.
This elevation makes pregnant women resistant to antihypertensives that operate through this
gateway.
The main urinary functional and anatomical
changes are summarized in Fig.2.6.
vitamin, or phosphate are
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2.2.11 Musculoskeletal System
In contrast to other systems, alterations in the
musculoskeletal system are due to anatomical
changes and not hormonal uctuation.
2.2.11.1 Diastasis Recti
In many cases, the abdominal rectus is not able to
stand the tension that it is subject to. For that reason, the muscle separates at the midline in what is
called diastasis recti. It may be physiological, but
if it is severe, it may involve ventral hernia [1].
2.2.11.2 Lordosis
There is a compensation of the convexity of
abdominal enlargement. This mechanism tries to
maintain the center of gravity in its position (otherwise, the woman would fall forward). This
change causes backache and numbness and fasciculation in the upper limbs [1].
2.2.11.3 Separation ofSacroiliac,
Sacrococcygeal, andPubic
Joints
Progesterone and relaxin act on ligaments that
are more relaxed during gestation. In addition, as
a way to prepare for childbirth, the pubic symphysis separates around week 30.
2.2.11.4 Calcication
If the diet of the pregnant woman is adequate,
loss of calcication should not be a problem.
Although requirements increase due to the fetus
and an elevated concentration of parathyroid hor-
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Renin
Angiotensin
Aldosterone
altered
T. Costas and M. Gomes-Ferreira
FLOW (75%)
Glomerular
filtration
(50%)
Ureters are
compressed
(Right)
Bladder is relaxed
and is compressed
Fig. 2.6 Main urinary functional and anatomical changes
mone levels, the lower loss through the kidney
and the increase in intestinal absorption should
be enough [1].
2.2.11.5 Gait andFeet
The change in the gravity center, the increase of
ligament relaxation, and the weight gain cause
greater instability and more falls in pregnant
women.
The feet suffer during pregnancy. The weight
gain affects the feet considerably due to their situation and function. Castello and colleagues
describe changes in the footprint during
pregnancy:
The plantar pressure increases progressively
in the sides and in the ankle zone, and the footprint changes. More than 38% of all pregnant
women in this study reported “discomfort” or
“pain,” but they did not consult with a doctor.
Many of them considered this “discomfort”
normal. Castello and colleagues also report that
Cortex is swollen
Collecting system is dilated
(smooth muscle)
many of these problems could be solved with
insoles or adequate shoes [8].
Also, the weight gain can lead to fascial tension which causes pain after rest (plantar fasciitis). In addition, an increase in BMI may
compound onychocryptosis.
Another equally relevant factor is exibility
lost due to an increase in abdominal volume. This
may not allow pregnant women to have a proper
hygienic routine and inspection of their feet.
2.2.12 Skin
The skin is one of the most damaged organs during pregnancy. Many of the changes are remarkable and noticeable for pregnant women. Rathore
etal. developed a study in which they carried out
a dermatological examination of 2000 pregnant
women randomly selected. In 87% of them, they
found physiological changes in the dermis [9].
2 Physiological andHormonal Changes During Pregnancy
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For that reason, we should inform our patients
previously [1].
The main factor in these changes seems to be
hormonal changes, although there is no study on
this particular topic and further research is
needed.
2.2.12.1 Hyperpigmentation
Hyperpigmentation is the change in the coloration of the skin (or part of it), which becomes
darker. It may happen due to estrogens that stimulate melanocytes and to human chorionic
gonadotropin (GhC) being biochemically similar
to melanotropin. However, there are no consistent studies on this eld.
Typically, hyperpigmentation affects the skin
of the middle abdominal wall (linea alba), the
newly formed linea nigra, the areola, and the perineal area (Fig.2.7).
Also, browning patches may appear on the
head and neck, and they are called chloasma or
melasma gravidarum (mask of pregnancy)
(Fig.2.8).
They should disappear after pregnancy and on
a few occasions, retinoid treatment may be necessary [4].
21
Fig. 2.8 Slight melasma on the forehead of a woman at
13weeks pregnant
2.2.12.2 Stretch Marks
They are a common problem in more than half of
all pregnant women. They appear on the lower
abdomen, thighs, and arms. Initially, they should
Fig. 2.7 Linea alba in woman at 32weeks pregnant
Fig. 2.9 Grey stretch marks on a thigh
be pink to purple, but over time, they become
white.
The strongest factors related to stretch marks
are the young age of the mother and family history (but not weight gain) [4]. There is no treatment for them (Figs.2.9 and 2.10).
2.2.12.3 Vascular
Vascular spiders (angiomas) appear in 75% of the
pregnant women. They are related to estrogen
concentration and the typical zones are the thorax, forehead, and arms.
Palmar erythema appears in 50% of all pregnant women, and it is also related to estrogens.
It usually disappears spontaneously [4].
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Fig. 2.10 Pink to purple stretch marks in a postpartum
abdomen
2.2.12.4 Hair
During pregnancy, there is more hair in the anagen phase (growing) than in the telogen phase
(resting). For that reason, at the end of pregnancy,
there is transitional alopecia. We should explain
that the normal loss of hair will be recovered [4].
Also, it is important to explain that it is not
advisable to use depilatory methods such a laser
hair removal because the skin is very sensitive
during pregnancy and it can be easily burned
(Figs.2.11 and 2.12).
More information about skin changes and
recovery is discussed in Chap. 10.
T. Costas and M. Gomes-Ferreira
Fig. 2.11 Burns in thighs after laser hair removal treatment during pregnancy
2.2.13 Other Systems
2.2.13.1 Vision
Blurred vision is a common symptom. Edema
(uid retention) and the decrease in intraocular
pressure are the causes of this problem. It should
disappear in the postpartum period.
A loss in accommodation has also been
described, and it disappears on its own.
For these reasons, pregnancy is not a suitable
period for vision correction adjustments [1].
2.2.13.2 Smell
There is next to no evidence about changes in the
sense of smell during pregnancy. Women report
increased olfactory acuity, but in contrast, Gul
Fig. 2.12 Another case of burns in thighs after laser hair
removal treatment during pregnancy
2 Physiological andHormonal Changes During Pregnancy
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etal. describe a decreased sensitivity during the
rst trimester that returns to normal levels during
the rest of the gestation period [10]. Further studies are necessary in this eld [1].
2.2.13.3 Superior Functions
A lot of pregnant women complain about memory loss during pregnancy. The studies are few,
and, at this moment, pregnancy does not seem to
affect memory [1].
2.2.13.4 Psychological Functions
Hormones can affect pregnant women in various
ways. It is usually associated with ambivalence
and frequent mood changes, ranging from anxiety to fatigue, exhaustion, sleepiness, depressive
reactions, and excitement. During pregnancy,
changes include body appearance, affectivity,
and sexuality, whereas the position and role of
women attains a new status. We will discuss these
important aspects in Chap. 4.
2.3 Conclusions
In conclusion, we should understand the main
body changes that pregnancy produces in a
woman. Pregnancy is a unique moment in the life
of a woman, and her body goes through changes
that it is not going to experience in any other situation. The complexity and integrity of the changes
are crucial for a good development of the fetus
and maternal well-being.
Many of the changes are physiological body
adaptations for the sake of developing a new life
and others are “adverse effects” that the body
tries to counteract. Our mission is observing all
these changes and nding the pathological ones
to help the mother and the fetus in this extraordinary process.
References
1. Cunningham FG, Leveno JK, Bloom LS, Spong
YS, Dashe SJ, Hoffman BL, Casey BM, Shefeld
SJ.Williams obstetrics. 24th ed. NewYork: McGrawHill Education/Medical; 2014.
2. Straach KJ, Shelton JM, Richardson JA.Regulation
of hyaluronan expression during cervical ripening.
Glycobiology. 2005;15:55.
3. Hein M, Petersen AC, Helming RB.Immunoglobulin
levels and phagocytes in the cervical mucus plug
at term of pregnancy. Acta Obstet Gynecol Scand.
2005;84:734.
4. Beckmann RB, Ling W, Barzansky M, Herbet NP,
Laube W, Smith P.Obstetrics and ginecology. 6th ed.
Philadelphia: Lippincott Williams and Wilkins; 2010.
5. Hibbard JU, Shroff SG, Cunningham
FG. Cardiovascular alteration in normal and preeclamptic pregnancies in Chelsey’s Hypertensive disorders in pregnancy. 4th ed. Amsterdam: Academic;
2014.
6. Mor G, Cardenas I. The immune system in pregnancy: a unique complexity. Am J Reprod Immunol.
2010;63(6):425.
7. Mor G, Cardenas I, Abraham V, etal. Inammation
and pregnancy: the role of the immune system at the
implantation site. Ann N Y Acad Sci. 2011;1221:80.
8. Castelló F, Macián-Romero C, Eulalia J.El calzado
en las embarazadas. Estudio estadístico. El Peu.
2009;29(3):136–45.
9. Rathore SP, Gupta S, Gupta V.Pattern and prevalence
of physiological cutaneous changes in pregnancy: a
study of 2000 antenatal women. Indian J Dermatol
Venereol Leprol. 2011;77(4):402.
10. Gul A, Yilmaz B, Karababa S, et al. Evaluation of
smell function changes in pregnancy. Kulak Burun
Bogaz Ihtis Derg. 2015;25(2):92–6.
Pregnancy andParturition:
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ThePhysical andPhysiological
Changes andTheir Pathologies
TallaWidelock, JereyDenney, andBrianBrost
3
Take-Home Points
• This chapter is intended to provide delivering
clinicians with a succinct overview of the normal
changes experienced over gestation and delivery
by women and how pathologic processes may
arise to guide perspective and thoughtful management of pregnancy and childbirth.
• The female anatomy undergoes mechanical
and physiological adaptive changes during
pregnancy.
• Endocrine- and immune-mediated processes
facilitate the necessary alterations of the
maternal reproductive organs and pelvic oor
to accommodate and sustain gestation for the
growth and development of the fetus.
• As term pregnancy is achieved, further modications of the uterus, cervix, pelvis, and the
pelvic oor in preparation for the safe passage
T. Widelock · J. Denney
Section on Maternal-Fetal Medicine, Department of
Obstetrics and Gynecology, Wake Forest School of
Medicine, Winston-Salem, NC, USA
e-mail: twideloc@wakehealth.edu;
jdenney@wakehealth.edu
B. Brost (*)
Division of Maternal Fetal Medicine, Department of
Obstetrics and Gynecology, University of Kansas
School of Medicine, Kansas City, KS, USA
Section on Maternal-Fetal Medicine, Department of
Obstetrics and Gynecology, Wake Forest School of
Medicine, Winston-Salem, NC, USA
e-mail: bbrost@kumc.edu
of the fetus, ideally, without signicant injury
to the mother.
• Labor onset is followed by the most physically rapid and anatomically evident changes
that likewise pose the greatest risk of injury to
the pelvic oor and birth canal.
• Pelvic oor disorders are often rooted in the
events occurring as the fetus is expulsed from
the uterus and birthed.
3.1 Introduction
The maternal bio-physiological clock is set to
maintain gestation until the fetus is mature enough
to maintain and sustain life as a neonate ex utero.
Fetal development and maturation is the core
objective of pregnancy. The maternal pelvis and
reproductive organs undergo signicant and yet
necessary changes in order to accommodate the
growth and development of the fetus and later to
allow for safe passage of the fetus during delivery.
For example, a number of endocrine and immunemediated mechanisms trigger histologic changes
in the uterus (to allow for expansion, growth, and
increased circulatory capacitance); cervix (to
facilitate softening, thinning, and dilation for passage of the fetus); pelvic oor and vaginal musculature (to decrease tensile strength and enable
atraumatic stretching for passage of the fetus);
and, nally the maternal bony and ligamentous
pelvis (to increase the circumference of the pelvic
© Springer Nature Switzerland AG 2023
M. Gomes-Ferreira, J. Olivas-Menayo (eds.), Post-maternity Body Changes,
https://doi.org/10.1007/978-3-030-43840-1_3
25
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