Menstrual cycle is very specific and individual, and can range from 24 days to 37 days.
The length of the menstrual cycle may be affected by many things, including illness, stress, travel, fertility
medication, and some other factors.
In most cases the duration of the menstrual cycle is 28 days. If the cycle is 28-day, the first day of bleeding
should be considered as a first day of the cycle. It is important to remember for calculations.
Every month female ovaries begin to ripen several follicles, which is why days 1–14 are called the
follicular phase. Each of the many follicles in the two ovaries is a pocket of tissue filled mostly with
estrogens. The number of active follicles changes with each cycle, but typically only one follicle per month
in a single ovary becomes dominant over the others and produces a viable egg. As the follicles ripen,
estrogen levels rise.
Just before mid-cycle, the hypothalamus and pituitary gland release LH (luteinizing hormone) and FSH
(follicle stimulating hormone) spikes to trigger the dominant follicle to ovulate. Estrogen levels continue to
rise. Contraception should be used during this period.
Days 14–28 are termed the luteal phase, when estrogen levels begin to fall and progesterone levels rise.
Around day 14 (but it can vary) ovulation occurs: the dominant egg is released from the follicle and is
drawn into the fallopian tube on its way to the uterus. This triggers a host of hormonal secretions —
including estrogen — that thicken the uterine lining to support a pregnancy.
Important to remember - women are fertile for about 24–48 hours around the time of ovulation (before
and after ovulation).
But how long can sperm survive in a woman? The answer is a very difficult one and depends on a large
number of variables including the individual longevity of sperm, the internal metabolic capacity of sperm,
the environment of the vagina (body temperature, pH levels, relative acidity), the presence of cervical
mucus, the quality of cervical mucus, the ability of the sperm to get out of the vagina and into the womb,
and the presence of sperm antagonists like immunity securing white-blood cells.
If consider the most ideal conditions (ideal vaginal/uterine environments, fertile eggs, strong sperm
health, etc) sperm may be able to survive between six and seven days. That's about a quarter of a
typical menstrual cycle - and that means an extended window of fertility before ovulation. In most cases,
however, we can assume that there will be realistic factors that may decrease sperm longevity or inhibit
sperm movement. First of all, the sperm needs to get out of the vagina and move into the uterus (through the
cervix). If the sperm can't make that initial leg of the journey in a few hours, most will end up dead shortly
thereafter. Now, if fertile-quality cervical mucus is present and abundant, and if the sperm make it to the cervix
and the womb, then sperm life-span can be extended. On average, we can expect sperm to survive just a
day or two, and given more optimum conditions or luckier happenstance, a handful of days more. Of
course, with each passing day more and more sperm die and the odds of conceiving diminish.
If you a not planning pregnancy, better use safe contraception especially during fertile days.
This method is based on an observation that the ovulation in females takes place 2 weeks
before menses. Now as we know that the menses cycles in women may not be on precise
day every month, the calculation of the safe period is done on the basis of duration of 12
previous cycles. First note down the shortest and the longest cycles during the last 12 cycles.
The first fertile day will be minus 18 days from shortest cycle.
The last fertile day would be minus 11 days from the longest cycle.
For example :
if the short cycle is 25 days the first fertile day would be ( 25-18 ) - 7th day
if the longest cycle is 32 days, the last fertile day would be ( 32-11 ) - 21st day.
Thus there should be abstinence for 2 weeks from 7th to 21st day.
This method is based upon observation of Ogino, in 1930 in Japan and Knaus, in 1933 in
Austria. One should keep in mind that this method of contraception is some what crude.
Discover more about Calendar Rhythm Method in following page.
READ MORE about contraception, condoms, IUDs, dual contraception, emergency
contraception, pills, sexually transmitted infections, HIV/AIDS, yeast infection and FAQs.
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