STRUCTURE OF MATERNAL PASSAGES AND PHYSIOLOGY OF THE BIRTH ACTIVITY.

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LECTURE ? 7

• STRUCTURE OF MATERNAL PASSAGES AND PHYSIOLOGY OF
  THE BIRTH ACTIVITY.
• Dr. Nagayeva S.

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FEMALE GENITALS

• For clear picture there is short description of
  anatomy and physiology of reproductive apparatus.
• Large and small lips of pudendum
• Vagina
• Uterus - consists from 3 parts - cervix of the
  uterus, an isthmus, body of womb.
• Tubes
• Ovaries
• Ligamentous apparatus
• of the womb and of the
• ovaries

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• Muscles of a womb settle down in three layers,
  thus each layer of muscles has its own
  direction. There is a network of blood vessels
  develops in thickness of womb's muscles and they
  are connecting with vessels of a placenta.
• Because of fast growth the womb and small
  dimensions of a fetus at the first and second
  trimesters , the last one freely settles down in
  a cavity of amniotic sack. The fetus grows in the
  third trimester more quickly and settles down in
  the most physiologic position cranial
  presentation (in most cases).

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CRANIAL PRESENTATION

• At that , movements of a fetus are better felt in
  the field of a bottom or edges of an uterus. At
  the first pregnancy the head of a fetus starts to
  fall to a cavity of a small basin at 38 week. At
  secundiparas this process occurs at the beginning
  of the birth activity.

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WHAT MAY TO HINDER FROM HEAD SINKING

• a short umbilical cord or repeated cord
  entanglement
• wrong position of a head (overextension)
• incorrect attitude of the fetus
• increased tone of the lower segment of the uterus
• Tumors of the presentation part or of the
  maternal passages, congenital anomalies of
  development the fetus
• the large dimension of a fetus
• placenta previa
• narrowed or deformed female basin

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• Fetal head nestles to a small basin and divides
  amniotic fluid on front and back amniotic fluid
  . Such division of amniotic fluid promotes soft
  painless uterine cervix effacement during birth
  activity. In some cases such division of
  amniotic fluid hasn't been occur. As a result the
  capsule of the fluid sack stretches on a head
  and slows down the process of uterine cervix
  effacement. That in it turn leads to weariness of
  the lying-in woman.
• Such pathology demands medical assistance.

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• From 30 weeks of pregnancy the woman start to
  feel solitary short-term prenatal contractions
  (Braxton - Hicks contractions). These
  contractions appears under influence of a hormone
  oxytocin on an uterus. The contractions leads to
  gradual structural maturing of uterine cervix.
  Besides that they carry out easy gymnastics of
  your child in a tummy.

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• From 37 weeks these contractions has been
  appeared more often and as a rule at the
  evening. These contractions do not cause uterine
  cervix effacement . Therefore they called false
  (or harbingers of sorts). Besides they are not
  periodical and disappear themselves. At this
  period you can lose the mucus plug . It looks
  like mid-size mucous piece , colored from light
  cream to light brown .

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• Such contractions can lead the premature rupture
  of amniotic fluid sack. You should go to
  maternity home immediately , if you caught sight
  of liquid discharge from genital tracts.
• The long waterless interval increases the risk of
  intrauterine infection and can entail fetal death.

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STAGE OF DILATION

• Labor begins at the certain hormonal background
  of female organism. Exuded oxytocin causes
  regular uterine contractions. Normal the center
  of stimulation appears in the uterine bottom,
  from which a chain of electric impulses spreading
  along the whole length of the uterus. That
  produce contraction at all three layers of an
  uterine muscles. During contraction the muscle
  are shortening , displacing about each other,
  thereof the uterine capacity decreases and the
  intrauterine pressure increases. These pressure
  passing by means the aquatic environment and the
  fetal bladder filling and wedging in the cervical
  canal of uterus.
• That promotes tender and painless uterine cervix
  effacement.

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STAGE OF EXPULSION

• When uterine cervix become smooth completely and
  opens on 10 sm., the fetus will start the forward
  - turning movement. While the cervix of the
  uterus has been opened , the fetus has been
  prepared for forthcoming travel too.
• Under influence of contractions he specialized to
  the size of the maternal passages. For the
  beginning it has bent a head to pass by the
  smaller diameter of a head through the maternal
  passages.
• Then soft bones of a skull of a fetus have
  started to be displaced one for another. In such
  condition it will move through the maternal
  passages.

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STAGE OF EXPULSION

• He feels greater workload and the expressed
  oxygen insufficiency during the birth
  contractions. His heartbeats are up to 160-180
  beat per minute. That's why it is important for
  woman to be able to correctly breathe. In the
  pause he is resting together with mum, the
  rhythm of its heart is restored. During labor the
  fetus passes through wide and narrow parts of a
  basin. In a narrow part of a basin loading on a
  fetus is the greatest.

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THE AFTERBIRTH STAGE

• The birth process ends with the birth of
  placenta. There are new series of contractions
  after birth, occurring within 5-10 minutes.
• They are banishing a placenta and an amniotic
  fluid from the uterus. The uterus contracts and
  settles down below the navel.

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EARLY AFTERBIRTH PERIOD

• This period (2hours) is threatened of
  complications (bleeding). Recently confined woman
  spends this time on labor bed under supervision
  of the medical personnel. After 2 hours, at
  absence of complications ,she and her baby are
  moving to "Mother and the Child " department.