Childbirth which prevent uterine contractions while the baby

Childbirth known parturition, usually occurs within 15
days of the calculated due date (280 days from LMP). The parturition means a
process of delivering the baby and placenta from the uterus to the vagina to
the outside world called labour and delivery. There are series of events that
propel the infant from the uterus, are referred to collectively as stages of
labour. The precise trigger for labour is not clear because some women maybe
overdue more likely if it is a first baby.

Human chorionic gonadotropin (HCG): stimulates the production
of oestrogen and progesterone within the ovary, production of this hormone
diminishes once the placenta is mature enough to take over oestrogen and
progesterone production which are secret by the corpus luteum.

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Oestrogens help regulate levels of progesterone and
prepare the uterus for the baby, progesterone contains high levels of hormones
which prevent uterine contractions while the baby is still developing and
therefore decrease, for labour to occur. By preventing contractions of the
uterus. (Braxton hick’s contractions), painful contractions accompanied by
thinning and the opening of the cervix up to 4cm, lasting 35-45 seconds and
occurs during the latent phase of the first stage of labour, that may last for
a very long time, especially for first time mums and the length of this phase
can range from six hours to two-three days.

As oestrogen begins to stimulate uterine contractions,
the pituitary gland releases hormone from the mother called oxytocin hormone
that stimulates contractions of the uterus during achieving childbirth and
labour that stimulates the placenta and produce prostaglandins, tissue hormone
that helps start labour and used to induced labour. These contribute to the
decrease of progesterone level, initiating labour along with the relaxin
hormone which relaxes the muscle of the cervix, in the final phase of the first
stage of labour is transition stage, causing the cervix to dilate from about 4
centimetres to 7 centimetres (10 centimetres, making room for the baby to pass
through), indicating   fully dilated
cervix, usually 6-12 hours or longer. Leading to active labour in the first
stage of labour. Which leads to the expulsion of the foetus from the mother’s
uterus in the second stage of labour, this stage takes as long as 2 hours, it is
typically 50 minutes in a first birth and around 20 minutes in subsequent
births.

However, the final stretch of growth stretches the uterus
to its limits which put a physical stress, on both the baby and the uterus,
causing the releases of a stress hormone called corticotropin-releasing hormone
(CRH) and cortisol, increase during the last few days and weeks of gestation.
When it rises, it triggers a rise in the steroid hormone called estriol a form
of oestrogen that is major during childbirth. which inhibits the synthesis of
progesterone by the placenta and prepares the smooth muscles of the uterus for
labour, leading to the third stage of labour in the delivery of the baby ending
with the delivery of the placenta and the empty bag of waters that are attached
to the placenta (membranes). A structure or tissue, such as the chorion, amnion
sac that comes away as the Uterus (womb) contracts down after birth. This is
the shortest stage and usually accomplished 15 minutes after the birth of the
baby.

5.2    EXPLAIN THE CHANGES IN THE FOETAL
CIRCULATION AT BIRTH

Foetal circulation and changes also occur before birth,
when the foetus is not capable of respiratory function and therefore relies on
the maternal circulation to carry out gas, nutrient and waste exchange. The
foetal and maternal blood never mix, instead, the interface at the placenta
because nutrient and oxygen are passed over by diffusion only and if the
mothers and foetus blood mixed, it could be deadly for both of them. As a
result, the liver and the lungs are non-functional, and a series of shunts
exist in the foetal circulation so that these organs are almost completely
by-passed.

After birth, during the first stage of labour blood
occurs in the Ductus venosus a trumpet-shaped vessel, provides a means for
oxygenated umbilical vein blood to bypass the sinusoids of the liver. The
amount of blood passing through the vessel seems to be regulated by a sphincter
mechanism. For example, to prevent an excessive venous return to the right side
of the heart during uterine contractions, there is a relative contraction of
the ductus venosus.

This flows into the right atrium and is directed towards
the foramen ovale, a small hole located in the septum, which is the wall
between the two upper chambers of the heart (atria) with  an anatomic adaptation in the foetus that
allow oxygenated blood coming from the umbilical vein through the inferior vena
cava to bypass the pulmonary circulation. It is mixed with a small volume of
blood returning from the non-functional lungs through the pulmonary veins and
passes into the systemic circulation thereby bypassing the lungs. The following
structures pass through foramen ovale: Mandibular nerve. The motor root of the
trigeminal nerve. Accessory meningeal artery (small meningeal or peridural
branch, sometimes derived from the middle meningeal artery).

 While the ductus
arteriosus, also called the ductus Botalli, is a temporary blood vessel
connecting the pulmonary artery (the main heart vessel leading to the lungs) to
the proximal descending aorta (the main blood vessel of the body). It allows
most of the blood from the right ventricle to go around the foetus’s
fluid-filled non-functioning lungs before birth. Most of the blood in the aorta
is then returned to the placenta for oxygenation through the umbilical
arteries. Blood is emptied into the aorta after the artery head has branched
off through ensuring that the brain receives well-oxygenated blood.

Changes at and after birth occur when the pressure
changes due to inflation of the lungs and the increased flow through the
pulmonary arteries close the foramen ovale and the ductus arteriosus muscular
wall contracts and close and is effectively obliterated within 2 months,
becoming the ligamentum arteriosum. The ductus venosus becomes the ligamentum
venosum (passing around the caudate lobe of the liver), and the intra-abdominal
umbilical vein becomes the ligamentum teres.The umbilical arteries become
obliterated and form the medial umbilical ligaments (not to be confused with
the median umbilical ligament which is the obliterated remains of the urachus).

6.1,
Explain the hormonal control of lactation.

Lactation is under endocrine control. The two main
hormones involved are prolactin and oxytocin. Prolactin is the hormone that stimulates mammary
gland development and stimulates milk production called lactogenesis. During pregnancy, the body prepares for lactation by
stimulating the growth and development of branching lactiferous ducts and
alveoli lined with milk-secreting lactocytes.

By the end of the 6 month the mammary glands
are fully developed, and gland cells begin to produce a secretion known as
colostrum. These functions are attributable to
the actions of several hormones, including prolactin. Following the
first two or three days of childbirth, mammary gland secretion of breast milk suckling triggers and Stimulated tactile
receptors stimulate the release of oxytocin from the posterior lobe of the
pituitary gland. Oxytocin causes contraction of the myoepithelial cells in the
walls of the lactiferous ducts to squeeze milk
from alveoli and milk is ejected.

The delivery of the placenta and the resulting
dramatic reduction in progesterone, oestrogen, and human placental lactogen
levels stimulate milk production. The milk produced in the first
postpartum days, contains more protein and less fat than breast milk, and
many of the proteins are antibodies that may help the infant fight off
infections until its own immune system develops.
Mature milk changes from the beginning to the end of a feeding, whereas,
Foremilk quenches the infant’s thirst, whereas hind milk satisfies the infant’s
appetite.

6.2,
Explain the difference between milk and colostrum.

The colostrum is
yellow in colour and thick and the mature milk is white in colour and thin. Whereas,
breast milk is roughly divided into 2 stages. It first comes out in about a
week after childbirth is called colostrum and one after that is called mature
milk.

While colostrum is
yellow in colour and thick. At the beginning, it comes out just like oozing
from the nipples. As the baby suckle, the quantity get increased. And after
7-10days, the colour of breast milk becomes white in colour and thin. The
quantity of it increases gradually and the breasts come to be bloated, so it is
happening that breast milk comes out from nipples a lot.