Pregnancy causes many anatomical, physiological, and biomechanical changes in the body to support fetal development and birth. The uterus grows enormously over the course of pregnancy. Other systems like cardiovascular, respiratory, and renal systems also adapt to support increased demands on the mother. Hormonal changes induce physical changes in breasts, skin, ligaments and other tissues. Proper understanding of normal pregnancy changes helps healthcare providers manage common issues and risks.

4. -Pregnancy is associated with normal
anatomical, biomechanical & physiological
changes to provide suitable environment for fetal
development, to cater to the increased metabolic
demands and to prepare for the childbirth.
-It is important to healthcare professionals to
know the normal parameters of change in order
to diagnose and manage common medical
problems of pregnancy, such as hypertension,
gestational diabetes, anemia and
hyperthyroidism.

5. The Reproductive System Changes
(1) Changes in the uterus are phenomenal. By the time
the pregnancy has reached term, the uterus will have
increased about five times its normal size:
(a) In length from 8 to 35 cm.
(b) In depth from 2.5 to 20 cm.
(c) In width from 5 to 25 cm.
(d) In weight from 50 to 1000 grams.
(e) In thickness of the walls from 1.25 to 0.5 cm.
A. Uterus:

6. (2) The capacity of the uterus must expand to normally
accommodate a 3.5 Kg fetus and the placenta, the
umbilical cord, the amniotic fluid, and the fetal
membranes. So, it increases from
4 ml in non-pregnant state to 4000 ml at term.
(3) During pregnancy as the uterus expands and moves
out of the pelvis, the round ligaments and the
uterosacral ligaments can be stretched which causes
discomfort in some women.
(4) Formation of lower uterine segment: After 12 weeks,
the isthmus (0.5cm) starts to expand gradually to form the
lower uterine segment which measures 10 cm in length at
term.

7. (5) The abdominal contents are displaced to the sides as
the uterus grows, the uterus usually undergoes rotation
with tilting to the right (dextro-rotation), probably due
to presence of the rectosigmoid colon on the left side.
-The size of the uterus usually reaches its peak at 38 weeks
gestation. The uterus may drop slightly as the fetal head
settles into the pelvis, preparing for delivery. This dropping
is referred to as (lightening).
-The increase of uterine weight is due to hypertrophy of the muscle fibers (estrogen effect),
their multiplication (progesterone effect) and the increased mass of elastic connective tissue.
-From the first trimester onwards, the uterus undergoes irregular contractions called
(Braxton Hicks Contractions), which normally are painless.

8. -Formation of the Placenta that begins after blastocyst
implantation in the uterine wall.
-The placenta is the temporary organ that plays a critical role
regarding connection between the fetus and the mother.
-Throughout the pregnancy, It supplies nutrients and oxygen
and eliminates waste products of the fetus via the umbilical
cord (through one umbilical vein which imports oxygenated
blood to the fetus and two umbilical arteries which export
deoxygenated blood from the fetus). Also, the placenta
produces several hormones throughout pregnancy, each of
which plays an important role in supporting the pregnancy as:
Chorionic gonadotropin hormone, estrogens, progesterone and
human placental lactogen.

10. -The Cervix becomes hypertrophied, soft and bluish in color due
to edema and increased vascularity.
-After conception, a thick cervical secretion result of enlarged
and active mucus glands of the cervix obstructs the cervical canal
forming a mucous plug serves to seal the uterus and to protect
the fetus and fetal membranes from infection. The mucus plug is
expelled at the end of the pregnancy.
B. Ovaries:
-Both ovaries are enlarged due to increased vascularity and
edema particularly that containing the corpus luteum.
-Corpus luteum starts to degenerate after the 10th week of
gestation which secretes estrogen, progesterone and relaxin.

11. -Ovulation ceases during pregnancy due to pituitary
inhibition by the high levels of estrogen and progesterone.
C. Fallopian Tubes:
-The musculature hypertrophies and the epithelium becomes
flattened. also, sometimes if fertilized oocyte grows outside
the uterus this is called an ectopic pregnancy (90% occurs
in fallopian tubes), this can rupture fallopian tubes leading to
a major internal bleeding. It is a life-threatening emergency.
D. Vagina:
-Increased circulation to the vagina early in pregnancy changes as the vaginal walls become
more hypertrophied and more vascular.
-During pregnancy, pH of the vagina becomes more acidic and may develop varicose veins.

12. -Pregnancy hormones cause normal breast
tissue to change into milk-producing tissue.
This change occurs as early as the first trimester.
-As pregnancy progresses, the nipples and the
areola may darken in color also, beginning in
production of colostrum during the first few
weeks of the second trimester.
-Estrogen encourage growth and branching of
the lactiferous ducts during pregnancy,
Progesterone causes enlargement of lobules,
Prolactin prepares for milk production and
Oxytocin increases at the onset of labor and
during labor as a preparation for milk ejection.

13. The Endocrinal (Non-Reproductive)
System Changes
Pituitary hormones
-FSH/LH fall to extremely low levels due to the high
levels of estrogen and progesterone.
-ACTH levels increase.
-Melanocyte-stimulating hormone levels increase.
-TSH levels may increase.
-Prolactin levels increase.
-Pituitary growth hormone (GH) levels fall but overall
serum levels increase due to placental production.
-Oxytocin levels increase to a peak at term.
-ADH levels are unchanged.

14. Thyroid hormones
-Thyroxine-binding globulin (TBG) concentrations
rise due to increased estrogen levels.
-T4 and T3 increase over the first half of pregnancy
but there is a normal to slightly decreased amount of
free hormone in the second and third trimester due to
increased TBG-binding.
-TSH production is stimulated after the first trimester, a large rise in TSH is likely to indicate
iodine deficiency or subclinical hypothyroidism.
-Untreated maternal hypothyroidism can lead to increased risk of miscarriage, gestational
hypertension, preterm birth, low birth weight, and respiratory distress in the neonate.

15. Adrenal gland and Pancreatic hormones
-Cortisol levels increase in pregnancy, which favors
lipogenesis and fat storage.
-Insulin response also increases so blood sugar should remain
normal or low due to insulin resistance.
Peripheral insulin resistance increases after early stages of
pregnancy due to increased production of hormones such as
cortisol, prolactin, progesterone and human placental lactogen.
-Gestational diabetes is thought to reflect a pronounced insulin
resistance of this sort.
-HbA1c is not considered suitable for use in pregnancy.

16. The Cardiovascular System Changes
-As the diaphragm is elevated progressively during pregnancy
the apex is displaced upwards and to the left so that it lies in
the 4th intercostal space outside the midclavicular line.
-Cardiac output increases by 20% by week 8, and then
further up to 40% increase, maximal at week 20-28.
-In labor (Particularly during the 2nd stage) there is further
increase in cardiac output due to pain, uterine contractions
and bearing down. then a huge increase immediately after delivery.
-Contributing to the increased cardiac output are increased stroke volume and an
increase in resting heart rate of 10-15 beats per minute.

17. -There is a peripheral vasodilation due to estrogen and
progesterone effect so, Blood pressure is lower than normal in
the first two trimesters but returns to normal in the third trimester.
-The posture of the pregnant woman affects arterial blood
pressure. Typically, it is highest when she is sitting, lowest
when lying in the right lateral recumbent position and intermediate when supine.
-Supine hypotensive syndrome may develop in some women
late in pregnancy in supine position. This is due to compression
of the inferior vena cava by the large pregnant uterus resulting in
decrease venous return, decrease cardiac output and low blood
pressure that fainting may occur so, left side lying position is the best during these months.
-Changes on examination and ECG are caused by these physiological changes.

18. The Respiratory System Changes
-Tidal volume increases to provide more oxygenation (Oxygen consumption
is increased 20%) and respiratory rate does not alter significantly.
-The chest vertical diameter is decreased due to enlarged uterus
that compress the diaphragm superiorly, but the anteroposterior
and transverse chest diameters are increased.
-The average subcostal angle of the ribs at the xiphoidal level
increases from 68.5° at beginning of pregnancy to 103.5° at term.
-Hyperventilation with a state of compensated respiratory
alkalosis - arterial pCO2 drops, arterial pO2 rises. Lower maternal
pCO2 facilitates oxygen/carbon dioxide transfer to/from the fetus.

19. Non-Pregnant and Pregnant Lung Volumes

20. The Gastrointestinal System Changes
-Nausea and vomiting are common in early pregnancy
(Hyperemesis Gravidarum).
-The pregnant woman dislikes some foods and odors while
desires others (Longing or Craving). Reduced sensitivity of
the taste buds during pregnancy creates desire for markedly sweet or salt foods.
-Progesterone causes relaxation of the lower esophageal sphincter
and increased liability to heartburn. Pressure on the stomach from
the enlarging uterus further contributes to this in later pregnancy.
-Gastrointestinal motility is reduced, and This allows increased nutrient
absorption. Constipation and piles (due to pressure on pelvic veins) are common.

21. -Also, Constipation may be due to sedentary life during pregnancy
and increased water reabsorption from large intestine (aldosterone effect).
-The Gallbladder may dilate and empty less completely.
Pregnancy also predisposes to the precipitation of cholesterol gallstones.
-Gingivitis, Gums become spongy, friable, highly vascular and prone to
bleeding in about 50% of pregnant women due to hormonal changes give
rise to inflammation in the gums where the gums are more sensitive to
the bacteria.
-Excessive Salivation is more common and Indigestion is pronounced
due to decreased gastric acidity caused by regurgitation of alkaline
secretion from the intestine to the stomach and decreased gastric
motility(Progesterone effect).

22. The Urinary System Changes
-The increased blood volume and cardiac output during pregnancy
cause a 50-60% increase in renal blood flow and glomerular
filtration rate (GFR). This causes an increased excretion and
reduced blood levels of urea, creatinine and bicarbonate.
-Mild glycosuria and/or proteinuria may occur because the
increase in GFR may exceed the ability of the renal tubules to
reabsorb glucose and protein.
-Under Progesterone effect, the smooth muscle of the renal pelvis
and ureter become relaxed and dilated (especially the right side due
to dextrorotation), kidneys increase in length and ureters become
longer, more curved and with an increase in residual urine volume.

23. -Urinary stress incontinence may develop for the
first-time during pregnancy.
-Bladder smooth muscle also relaxes, increasing
capacity and risk of urinary tract infection.
-Frequent micturition is common in the first trimester
(due to congestion and pressure of the bladder by
the enlarged uterus) and third trimester ( due to pressure
by the presenting part after engagement).
-During pregnancy, mild hydronephrosis especially on
the right side due to uterine dextrorotation is considered
a normal phenomenon and may be present in up to 90%
of pregnancies.

24. The Hematological Changes
-Plasma volume increases over the course of pregnancy by about 50%
and there is a 20% increase in the total number of red blood cells (RBCs).
-Physiological or dilutional anemia in pregnancy accounts for increased
plasma volume more than increased red blood cells causes hemodilution,
which is greatest during the second trimester.
-Hemoglobin levels are decreased, the reason that fetal growth and development were
higher in the second and third trimesters which consumes a lot of nutrients from the mother.
-Iron deficiency is the most common nutritional deficiency in the world,
If developed during pregnancy, it significantly alters pregnancy outcomes as: low birth
weight, premature delivery and poor milk production.

25. -Hemoglobin concentration :lower than
11.6 g/dl in the first trimester,
9.7 g/dl in the second trimester,
and 9.5 g/dl in the third trimester
labeled as anemia for pregnant women.
-Anemia is the major contributory or sole cause in
20–40% of maternal deaths.
-Levels of some clotting factors (VII, VIII, IX and X), platelets and
fibrinogen increase whilst fibrinolytic activity decreases. These
changes protect from hemorrhage at delivery but also make pregnancy a
hypercoagulable state with increased liability of development of DVT.
-There is an increase leucocytes.

26. The Metabolic Changes
-The basal metabolic rate increases slowly over the course of pregnancy, by 15-20%.
-Active energy expenditure tends to fall over pregnancy.
-It is thought that energy requirement does not increase
significantly during the first or second trimesters.
-During the 1st trimester, the increase in weight is about
(1.6Kg), during the 2nd trimester(5.5-6.4Kg) and in the 3rd trimester only around 5 kg.
-There is tendency to water retention secondary to sodium retention.
-There is increased demand for iron, calcium, phosphate and magnesium.

27. The Integumentary System Changes
-Hyperpigmentation of the umbilicus, abdominal midline
(linea nigra) and face (chloasma gravidarum)) are common
due to pregnant hormonal changes especially high MSH.
-Hyperdynamic circulation and high levels of estrogen
may cause spider angioma and palmar erythema.
-Increased sweat and sebaceous glands activity, hair loss
and brittleness of nails are also common in pregnancy.
-Striae gravidarum (stretch marks) are common it begins
as (striae rubre) red color then it becomes
(striae albicantes) white color due to fibrosis.

28. The Musculoskeletal System Changes
-Increased ligament laxity is a physiological process caused by
increased levels of Relaxin, estrogens and Progesterone hormones
contribute to back pain, sacroiliac and pubic symphysis dysfunctions.
-Relaxin is a hormone secreted by the corpus luteum and the placenta
during pregnancy.
-Relaxin was shown to directly inhibit fibroblast differentiation into
myofibroblast expression, activate the collagenase enzyme which inhibit
collagen synthesis, decrease its tensile strength and deposition.
-Pregnant Joint pain (low back and hips) may be related to mechanical
changes and decreased ambulation rather than increasing laxity.

29. -Unlike bone and muscle where estrogen improves their
function, in tendons and ligaments estrogen decreases
their stiffness, and directly affects performance and injury rates.
-High estrogen levels can decrease power and performance
and make women more prone for catastrophic ligament injury.
-Diastasis recti is the partial or complete separation of the
rectus abdominis. it is very common during and following
pregnancy. This is because the uterus stretches the muscles
in the abdomen to accommodate the growing baby.
-For many women, pregnancy, as well as parturition,
represent the key physiological events predisposing to
pelvic floor dysfunction and incontinence.

30. The Postural Changes
-With weight gain, increased blood volume and ventral growth of the
fetus, the center of gravity no longer falls over the feet and women
may need to lean backwards to gain equilibrium resulting in
disorganization of spinal curves.
-Reported postures include an increase in both lumbar lordosis and
thoracic kyphosis or a flattening of the thoracolumbar spinal curve.
-There will be compensatory changes to posture in the thoracic and
cervical spines, and this combined with the extra weight of the
breasts may result in posterior displacement of the shoulders and
thoracic spine and increase of the cervical lordosis.

31. -COG shifts upward and forward
because of the enlargement of the uterus
and breast tissue.
-The lumbar and cervical lordosis
increase while knees are hyperextended.
-The shoulder girdle and upper back
become rounded with scapular
protraction and upper extremity internal
rotation.
-Weight shifts toward the heels to bring
COG to a more posterior position, so
planter fasciitis is common in pregnancy.

33. -Not only the torques of bilateral hip extension of pregnant females during the second and
third trimesters were smaller than the non-pregnant females but also, the bilateral planter
flexion torques in pregnant females were larger during the third trimester than the non-
pregnant females.
-The biomechanical alterations in step width and length which are consequences of
anterior tilting of the pelvis and wide pregnant pelvis.
-The gait of the pregnant women changed, reduction of
gait velocity, swing phase and increased hip internal rotation.
-Shift in posture with exaggerated lumbar lordosis, weak hip
abductors leading to the typical gait of late pregnancy.
-Pronated feet, knees out, back arched. it’s the pregnant-woman penguin waddle.

34. -Almost a quarter of the pregnant women experience
falling at least once and the risk of falling during
pregnancy is the highest during the 3rd trimester
especially during the seventh month of gestation.
-The falling rate during pregnancy is very close to that in
elderly women (26.8% and 29% respectively).
-Unfortunately, falls are the major cause for admission to
emergency department in pregnancy that can be attributed
to that Pregnant women face many anatomical,
physiological, and mechanical changes which may be
behind the increased risk of fall.
Risk of falling during pregnancy

35. -The center of gravity is shifted superiorly and anteriorly and the dynamic
postural control that is declined to its lowest levels during this 3rd trimester.
-When maintaining a standing posture, the ankle joint strategy, hip joint
strategy and step strategy are the three movement strategies used to counter
anterior-posterior translational motion.
-Postural sway of anterior-posterior movements
increased and the ankle joint strategy takes seniority
over the hip joint strategy in maintaining balance
during pregnancy compared to non-pregnancy as they
use their hip joint extensors less and their ankle plantar flexors more.
-Reliance on the ankle joint strategy indicates that they would have difficulty
controlling movement as the base of support shifts from the center outwards.

36. -Falling during pregnancy may cause serious complications to
pregnant woman and fetus.
-These falling complications may include the following: traumatic
head injuries, maternal fractures, placental abruption, uterine rupture,
premature rupture of membranes, internal bleeding and sometimes
maternal death or stillbirth.
-Fracture neck of femur may be a complication of fall during
pregnancy (due to trauma, transient osteoporosis during pregnancy
and weak hip abductors as when they contract there is a decrease in
the bending forces on the neck of femur).
-Pelvic fractures as pubic or acetabular fractures in pregnant
women are associated with risk of mortality to both mother & fetus.

37. Neuromuscular System Changes
-Passive joint instability (as seen in pregnancy) alters afferent
input from joint mechanoreceptors and probably affects motor
neuron recruitment.
-A decrease in muscle stiffness and thus active stability of joints
may result from alteration of muscle spindle regulation and
this is applicable particularly to muscles around the pelvic girdle.
-These changes may lead to poor recruitment of the muscles
responsible for pelvic girdle stability (particularly gluteus
medius and maximus) and result in decreased tension of these
muscles during walking, perhaps resulting in pelvic girdle pain.

38. -Carpal tunnel syndrome (CTS) is the most common compression
neuropathy of median nerve, which can occur or aggravate during
pregnancy, with a prevalence reported as high as 62%.
-Common chief complaints of CTS are numbness, tingling,
burning in median nerve region as well as the loss of grip strength.
-In pregnancy, the likely causes of CTS are hormonal changes and edema. Gestational
diabetes can also play a role due to generalized slowing of nerve conduction.
-Sciatica due to a herniated disc during pregnancy isn’t common. But
sciatic-like symptoms are common with low back pain in pregnancy.
-Sciatic symptoms can be caused by muscle tension (Tight piriformis) and unstable joints are
common causes of sciatic pain rather than enlarged uterine compression during pregnancy.

39. -Meralgia paresthetica (lateral femoral cutaneous
nerve entrapment) is a condition characterized by
tingling, numbness and burning pain in the outer thigh.
-The cause of meralgia paresthetica is the growing
uterus and weight gain can put pressure on the groin
that lead to compression of the nerve under the inguinal
ligament so, the sensation to the skin of anterolateral
surface of the thigh is affected.
-While it is often reported as a self resolving disorder, it can prove to be very uncomfortable
and even disabling for patients and shown to last for a duration of up to 16 months.
-Pudendal nerve terminal motor latency did not increase significantly during pregnancy but
increased significantly after delivery.

40. Prophet Muhammad (PBUH) said
“Treat women kindly”