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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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