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Related Links :
Menstruation | Ovulation
| Fertilisation | Calculation
of Fertile Period
Menstruation
Menstruation is a spontaneous cyclic (monthly) physiological shedding
of internal lining of uterine cavity (endometrium) due to invisible
interplay of female hormones. In simple terms, it is a regular monthly
bleeding which a woman experiences. The first menstruation occurs
usually at the age of 12 – 15 years. It is also called as ‘menarche’.
For the past couple of decades, the age of menarche is gradually
declining with improvement of nutritious and environmental conditions.
Once, the menstruation starts, it continues cyclically at an interval
of 22 – 35 days with a mean of 28 days.
Physiologically, it stops during pregnancy and lactation.
Ultimately, it ceases between the ages of 45 – 50 years when
menopause sets in.
The duration of menstruation (menses) is about 4 – 5 days and
the amount of blood loss is estimated to be 20 – 80 ml with an
average of 50ml.
The menstrual discharge consists of mainly a dark altered blood,
mucus, vaginal epithelial cell fragments of endometrium, prostaglandin,
enzymes and bacteria.
Usually, at the midcycle, a mature egg is released (ovulation).
If it gets fertilised, the menses ceases. Thus the absence of
menstruation suggests that pregnancy has occurred.
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Ovulation
Ovulation is a process by which a mature egg (mature Graffian follicle
after secondary oocyte is released) is released from the surface
of ovary to be available for fertilisation viz. conception.
Usually only one mature egg is released in each ovarian cycle.
In relation to the menstrual period, the event occurs 14 days
prior to the expected date of menses. However, menstruation can
occur without ovulation.
Fertility is very high during mid cycle, for the same reason.
Ovulation remains suspended during pregnancy and lactation.
Following ovulation, the mature egg (ovum) is picked up into
the fallopian tube and undergoes further maturation, if fertilization
has occurred or degeneration if it does not get fertilized.
Following ovulation, the ruptured follicle undergoes a change
called corpus luteum formation, which secretes hormone progesterone.
Menstruation is unrelated to ovulation and no ovulation during
menstrual cycle is quite common during young age (adolescence),
following childbirth and in women approaching menopause.
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Fertilisation:
 
Fertilisation is a process of meeting (after mating) of the sperm
with a mature egg.
It begins with sperm egg collision and ends with a formation
of life called zygote (single mononucleated cell mass)
The ovum immediately following ovulation is picked up by the
fimbrial end of the fallopian tube and is rapidly transported
to the ampullary part of the tube.
Out of hundreds of millions of sperms deposited in the vagina
after intercourse, only thousand specialised sperms enter the
uterine tube while only 300 – 500 reach the egg.
Out of this elite community, only one lucky member
is allowed to get into the mature egg.
The sperm either contains (22 X) or (22 Y) pattern of chromosomes
while the egg contains 22 X only.
The sex of the child is determined by the pattern of the sex
chromosome supplied by the sperm.
If the sperm contains (22 X) a girl child (46 XX) is formed,
if it contains (22 Y) a boy child (46 XY) is formed.
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Fertile
period:
The fertile period is period around ovulation, during which if relations
are kept, the chances of pregnancy are high. In order to improve
the chances of pregnancy, it is important to understand how to calculate
the fertile period.
Calculation
of a fertile period:
Mark the day 1 of your menses on a calendar. Do this for next 6
-8 cycles.
Note the length of the longest cycle and shortest cycle.
Subtract 18 from the length of the shortest cycle. Say you get
a figure "X"
Subtract 11 from the length of the longest cycle. Say you get
a figure "Y".
So the period you obtain between "X" and "Y" is the fertile period.
For e.g.Your shortest cycle is of 28 days, and the longest cycle
is of 30 days.
28-18=10
30-11=19
So your fertile period is from the 10th day to 19th
day.
As you know, the ovulation occurs approximately 14+ or -2 days
before the next menstrual period. So the highest fertility period
is around ovulation time i.e. mid cycle
The life span of the mature egg is approximately 48 hours (2
days) while the life span of the sperm is approximately 72 hours
(3 days). So even when the relations are kept on day 10 or 11
of the menstrual cycle success can be achieved.
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