The Base Facts
The information provided on this page in no way should be considered as complete. It is sufficient just to understand the ideas which were used while creating the Periodic Calendar application.
If you would like to get any additional information - please look for a good book or ask your doctor for recommendations.
A lot of usefull information can be found in the Internet as well. Just use your favorite search portal.
The Menstrual Periods
The monthly pattern that occurs regularly in most women, from puberty to menopause, is called the menstrual cycle. For some women, cycles recur regularly - every 28 days. But the number of days in each cycle may vary. After an initial 4 or 5 year adjustment period, the normal menstrual cycle length averages to 24 to 35 days.
Menstruation is a normal and predictable event. Every cycle has the following parts:
menstruation (period, bleeding)
luteal phase (after ovulation)
The beginning of the cycle, called Day 1, is the day when bleeding begins. The flow usually lasts about 3 to 5 days.
Usually by Day 7 some of the eggs in the ovaries start ripening. One egg is released from the ovary on about Day 14. The ovulation in most cases occurs about 14 days before the next menstruation. The time from menstruation to ovulation, may vary from 13 to 20 days in length from one woman to another, but also can differ for a women from month to month. Such common circumstances as sickness, worry, depression, malnutrition, physical exertion, and even sudden changes in climate may occasionally change the regular pattern by shortening it or extending it.
During ovulation the mature ovule (egg) travels down the fallopian tube toward the uterus. If a single male sperm unites with the egg while it is in the tube pregnancy begins. If fertilization doesn't take place, the egg cell will break apart in a day or two. About Day 25, hormone levels drop. This causes the lining of the uterus to break down and in a few days it is shed in a menstrual period. Another cycle begins. This part of the cycle, from ovulation to menstruation, has about the same length for all women. The egg is released consistently 14 to 16 days before the onset of menstruation, regardless of the length of a woman's menstrual cycle.
Sometimes woman can feel the signs or symptoms of premenstrual syndrome or PMS. To cure these symptoms, it can be very helpful to have the regular notes for each day describing the feelings and types of symptoms: headache, are you feeling bloated or retaining water, are you happy, or has it been a bad day? Just a word or two might help to discover a pattern emerging so that doctor can help more efficiently.
Conception and Contraception methods
The only method that is 100% efficient in the prevention of pregnancy is total abstinence. At the same time, there is no method 100% efficient for obtaining the pregnancy. The efficiency of all the family planning methods highly depends on the actions of the involved persons.
There are many contraception methods available to the public. The decision which method to use should be made considering all factors and possible consequences.
Many women avoid the use of chemical or hormonal contraceptives. There are plenty of reasons for that: secondary effects, a possible negative influence on health in present or future, some particular reactions of the body and many more. There could also be religious beliefs that forbid the use of contraceptives.
Using Fertility Awareness Methods, along with abstinence during the fertile periods is called Natural Family Planing.
The natural method of contraception is the safest method for health and it is suitable for the large majority of women. It has a high efficiency level (up to 95%). For a normal period of 28 days, this method allows 18 - 20 days of free sexual life.
The conceiving is possible only during the ovulation. The fertile period lasts maximum 5 days, because the spermatozoons may survive in the uterus up to 72 hours, while the ovule may survive 24 - 48 hours. The natural contraception method is based on the prediction of the ovulation date and the calculation of the fertile and non-fertile days. The fertile period (when conceiving is possible) is composed of the days right before and after the ovulation, when the ovule is released from the ovary and gets down through the fallopian tube through the uterus. This period can be estimated by using the date of ovulation and taking into consideration the lifetime for the ovule and for the spermatozoons. The ovulation occurs about 14 days before the next menstruation. During the fertile period, the sexual contacts should be avoided or other methods of contraception should be used, such as condoms or the interruption method (coitus interruptus).
The precise prediction of the ovulation date is essential for the safe use of the natural contraception method. This estimation makes the best results if the women have a regular menstrual period.
The easiest method to use is calendar method. The menstrual cycles are charted on a calendar. The ovulation date is predicted as 14 days before the estimated next cycle start. It is more difficult to predict the day of ovulation if the length of the cycle varies from month to month. In that case, more days should be considered as "unsafe". It is not recommended to use this method alone for the natural family planing.
If the cycle length is not stable (varies more than 2 days from one month to another) it is recommended to use additional methods.
The Basal Body Temperature (BBT) method is very well known and widely used. The basal body temperature is measured every morning before getting out of bed. The temperature rises between 0.4F and 0.8F (0.2C to 0.4C) on the day of ovulation and remains at that level until the next period.
For the cervical mucus method the changes in the cervical mucus are observed. This should be done through the first part of your menstrual cycle, until woman is sure she have ovulated. Normally cloudy, tacky mucus will become clear and slippery in the few days before ovulation. It also will stretch between the fingers. This means woman is in the most fertile phase.
The highest efficiency can be achieved if the temperature method, the cervical mucus method, and the calendar method are combined.
If the egg cell is united with a male sperm cell - a process called fertilization - it will enter the uterus, attach itself to the lining, and begin to develop into a fetus. The pregnancy starts.
The pregnancy age is recorded in weeks, starting from the first week of the last menstrual cycle. The week number is the most important parameter which is taken into account when considering treatments and supporting activities during the entire pregnancy time.
The average pregnancy length is 40 weeks, however the deviations in any direction are considered as normal. The child birth day is always just a prediction based on this average length value.