ЛЕКЦИЯ № 7
LECTURE № 7
STRUCTURE OF MATERNAL
PASSAGES AND PHYSIOLOGY
OF THE BIRTH ACTIVITY.
Dr. Nagayeva S.
For clear picture there is short description of
anatomy and physiology of reproductive
Large and small lips of pudendum
Uterus - consists from 3 parts - cervix of the
uterus, an isthmus, body of womb.
of the womb and of the
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
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).
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
WHAT MAY TO HINDER FROM
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
the large dimension of a fetus
narrowed or deformed female basin
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
Such pathology demands medical assistance.
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.
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 .
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
The long waterless interval increases the
risk of intrauterine infection and can entail
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
That promotes tender and painless uterine cervix
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.
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.
THE AFTERBIRTH STAGE
The birth process ends with the birth of
placenta. There are new series of
contractions after birth, occurring within 510 minutes.
They are banishing a placenta and an
amniotic fluid from the uterus. The uterus
contracts and settles down below the
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.