Inner cell mass

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Blastocoele
Becomes amniotic sac
Blastocyst (cross section)
Spermatozoa
Morula
Ovum (cross section)
Cleavage
Inner cell mass
Destined to become fetus
Fertilization
Trophoblast
Secondary oocyte (ovum)
Accomplishes implantation and develops into fetal
portions of placenta
Ovulation
Ovary
Implantation
Endometrium of uterus
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Surface of uterine lining
Decidua
Inner cell mass
Cords of trophoblastic cells
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Physiological and hormonal changes in pregnancy

• Chorion
• from day 8 until 4 months secretes hCG which
  keeps corpus luteum active
• corpus luteum produces progesterone estrogen to
  maintain lining of uterus

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hormonal changes in pregnancy (cont.)

• Placenta
• by 4th month produces enough progesterone
  estrogen
• relaxin which relaxes tissues of pelvis and cervix

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• human chorionic somatomammotropoin (hCS) or human
  placental lactogen (hPL)
• helps prepare mammary glands for lactation

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• corticotropin-releasing hormone (CRH) increases
  secretion of fetal cortisol (lung maturation)
  acts to establish timing of birth

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Hormonal Secretion by the Placenta
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Hormone Blood Levels

• Human chorionic gonadotropin (hCG) produced by
  the chorion is less important after 4 months,
  because the placenta takes over the hormonal
  secretion of the corpus luteum.

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Response of the mothers body to Pregnancy

• Weight gain
• Metabolism
• Digestive System and nutrition

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Response continued

• Cardiovascular System
• blood volume 30 above normal
• increased cardiac output, heart rate and blood
  pressure
• Cardiovascular changes to meet needs of fetus
• Respiratory System
• diaphragm is raised
• movement is restricted
• rate is increased
• increase in tidal volume 30

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Response

• Urinary System
• Increased glomerular filtration rate
• increased urine formation

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Labor and Parturition

• Parturition means giving birth labor is the
  process of expelling the fetus
• progesterone inhibits uterine contraction

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• Labor begins when progesterones inhibition is
  overcome by an increase in the levels of estrogen

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Figure 20.27Page 791
Human chorionic gonadotropin (hCG)
Estrogen
Progesterone
Fertilization
Delivery
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Why estrogen level is increased?

• placenta stimulates fetal anterior pituitary
  which causes fetal adrenal gland to secrete DHEA
• placenta converts DHEA to estrogen
• estrogen overcomes progesterone and labor begins

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• Hormonal Factors That Cause Increased Uterine
• Contraction
• Ratio of Estrogens to progesterone
• from 7th month onward estrogen secretions
• increased (progesterone remains constant)
• Effect of oxytocin on the uterus
• Effect of Fetal Hormones on the Uterus

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• Mechanical Factors That Increase the
  Contractility
• of the Uterus
• Stretch of the uterus
• Stretch of the cervix
• A positive feedback Theory

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Positive Feedback during Labor

• Uterine contraction forces fetal head into cervix
  (stretch)
• Nerve impulses reach hypothalamus causing release
  of oxytocin

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• Oxytocin causes more contractions producing more
  stretch of cervix more nerve impulses

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The blue arrows designate the sequence of events
leading to the onset of parturition. The green
arrows designate the positive-feedback
cycle responsible for the progression of
parturition.
Uterine contractions
Push fetus against cervix
Responsible for progression of parturition
(through neuroendocrine reflex)
Prostaglandin production
Oxytocin secretion
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True Versus False Labor

• True labor begins when contractions occur at
  regular intervals
• produces pain
• back pain increases with walking
• dilation of cervix with a discharge of
  blood-containing mucus in the cervical canal

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• False labor produces pain at irregular intervals
  but there is no cervical dilation

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3 stages of labor

• Stage of dilation
• 6-12 hours
• from onset of labor to the complete dilation of
  the cervix
• rupture of amniotic sac

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Placenta
Umbilical cord
Partially dilated cervix
Uterus
First stage of labor Cervical dilation
Second stage of labor Delivery of the baby
Third stage of labor Delivery of the placenta
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• Stage of expulsion
• from complete cervical dilation to delivery of
  the bacy
• 10 minutes to hours

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• Placental stage
• 5 30 minutes

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Obstetrical Complications

• Ante-partum
• Intra-partum
• Post-partum

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Ante-partum complications

• Pregnancy induced hypertension PET
  (pre-eclamptic toxemia) Toxemia of pregnancy
• Dysfunctional labor patterns

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contd.

• Abnormal placenta position
• Placenta previa
• Abruptio placenta

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Pregnancy-Induced Hypertension

• Elevated blood pressure
• Preeclampsia (PET)
• sudden hypertension
• large amounts of protein in the urine
• generalized edema, blurred vision headaches
• Eclampsia convulsions coma in mother

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Dysfunctional Labor Patterns

• Contraction insufficient to produce dilation and
  effacement
• fetal malposition
• excessive analgesia
• fetal post maturity
• increased maternal age

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contd.

• Premature rupture of the membranes
• increased maternal age
• cervical damage from surgical instrumentation

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Abnormalities of the placenta

• Placenta previa
• placenta implantation at the lower segment of the
  uterus
• obstructing the descent of the babys head
• presented with antepartum hemorrhage

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contd.

• Abruptio placentae
• premature separation of the placenta
• bleeding may be concealed or revealed

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Intra-partum complications

• Dystocia and prolonged labor
• Dystocia difficult labor
• due to fetal position or size
• breech presentation is butt or feet first in
  birth canal

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contd.

• Prolonged labor - ? considerCesarean section
  (C-section)
• horizontal incision through lower abdominal wall
  and uterus

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Post-partum complications

• Retained placenta due to abnormal implantation of
  placenta (placenta accreta)
• Post partum hemorrhage

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• Puerperium 6 week period following the birth of
  a baby
• Physiological changes
• uterus involution
• menstruation resume by 9-12 weeks post partum in
  70 of women (not lactating)
• weight loss to prepregnancy weight (6 weeks to 6
  months)

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• Most common complications
• Urinary tract infection
• Thromboembolism
• Depression fourth day baby blues

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Physiology of Lactation

• Lactation production release of milk
• After delivery, progesterone levels drop
  suckling increases the release of prolactin
  oxytocin (milk ejection reflex)

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• Colostrum cloudy fluid released for few days
• True milk produced by 4th day

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Benefits of Breast-feeding

• Faster better absorption of the right
  nutrients
• Beneficial cells
• functional white blood cells
• neutrophils help ingest bacteria in babys gut
• macrophages produce lysozymes
• plasma cells provides antibodies prevent
  gastroenteritis

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contd.

• Decreased incidence of diseases later in life
• reduction in allergies, respiratory GI
  infections, ear infections diarrhea
• Parent-child bonding

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Complications of breast feeding

• puerperal mastitis
• lactation failure due to infrequent suckling