Calendar method
The "Ogino-Knaus" method - otherwise known as the "calendar or rhythm method" - is a natural contraceptive strategy based on the theoretical calculation of the potentially fruitful days for women.
A couple can use the Ogino-Knaus method for two opposite reasons:
- Prevent pregnancy: in such circumstances, the couple must refrain from sexual intercourse during the days that, according to the Ogino-Knaus method, are fertile for the woman. Alternatively, the couple can prevent pregnancy by using - in the "at risk" period - other natural contraceptive methods (interrupted coitus, Billings method, thermo-thermic method, etc.) or barrier (eg male or female condom, cervical cap, etc.).
- Planning a pregnancy: the man and woman who want a child should prefer "fruitful" days to attempt conception.
It is however necessary to emphasize that the Ogino-Knaus model is not very reliable as a contraceptive method, given that it presents a very high risk of failure. Theoretically, only women with a perfectly regular menstrual cycle of 28-31 days could use the Ogino-Knaus method to prevent an unwelcome pregnancy.
Curiosity
The Ogino-Knaus method takes its name from the two doctors K. Ogino and H. Knaus who devised - although at different times and independently - the contraceptive practice.
Key points and principles of the method
What is the Ogino Knaus method?
To simplify the description, we describe the key points considered in the Ogino-Knaus method:
- The woman is not fertile during all the days of the menstrual cycle
- Fertility days are not the same in all women
- Menstruation begins about the 14th -16th day after ovulation
- Spermatozoa maintain their fertilizing capacity for 3-4 days inside the female genitalia (uterus)
- The egg lives only 12-24 hours
- In an ideal menstrual cycle (28 days), the fertile period is between the 10th and 17th day of the cycle
- To best apply the Ogino-Knaus method it is essential that the woman knows precisely the duration of her menstrual cycle
It should be pointed out that for many women the duration of the menstrual cycle is very irregular or in any case different from the "ideal" of 28 days. From what has been said, it is easy to understand how the fertile period of women can oscillate in an absolutely unpredictable way.
How to use the method
Given these premises, another question arises:
What, according to the Ogino-Knaus method, are the days when the woman is fertile (therefore "at risk" of pregnancy)?
Since it is almost unlikely that the woman has absolutely regular 28-day menstrual cycles, the shorter cycle time and longer cycle time observed by the woman over 12 months must be taken into account.
Having said this, it is possible to calculate the potentially fertile days (in which one should refrain from the relationship to avoid pregnancy) according to the application of two simple formulas (taken from the " Contraceptive Technology " manual).
- End of the infertile phase (before ovulation) = shorter cycle time (expressed in days) - 19
- Beginning of the infertile phase (after ovulation) = longer cycle time (expressed in days) - 10
In the period between the first and last day of fertility, the couple who do not wish to have children should refrain from full sexual intercourse (or adopt different contraceptive measures). Conversely, the man and woman who wish to become pregnant should prefer this period to attempt conception.
Practical example
To understand...
DATA
A woman in one year has 12 menstrual cycles, of which the shortest has had a duration (for example) of 26 days and the longest of 31
APPLICATION OF THE OGINO-KNAUS METHOD
- Last day of infertility (pre-ovulatory infertile phase): 26-19 = 7
- First day of infertility (post-ovulatory infertile phase): 31-10 = 21
INTERPRETATION OF THE OGINO-KNAUS METHOD
- The woman who wants children should try a pregnancy between the 8th and 20th day of the menstrual cycle to be more likely to have the egg fertilized. In fact, in the 7th day the woman is still infertile; it will be able to conceive starting from the following day (8th). Similarly, 21 indicates the day of return to infertility, so until the previous day (20th) the woman is still fertile.
- The woman who does not want children should refrain from sexual intercourse in the period between the 8th and 20th day of the menstrual cycle.
Advantages
Interpreted with an opposite interpretation, the Ogino-Knaus method is extremely effective for planning a pregnancy. In fact, the theoretical calculation of fertile days ensures that couples who wish children have a greater chance of conceiving.
Limitations
To take full advantage of the "contraceptive" effectiveness of the Ogino-Knaus method it is essential that the woman has an excellent awareness of her body and that her menstrual cycles are extremely regular.
Before using the Ogino-Knaus method as a first choice contraceptive strategy, it is estimated that the woman must carefully observe the progress of her cycles for 12 consecutive months. Only if the cycles are relatively regular (ranging from a minimum of 25 to a maximum of 31 days), then, the chances of success of the Ogino-Knaus method to avoid pregnancy are significantly higher.
The Ogino-Knaus method cannot be used during breastfeeding, since the resumption of regular ovulation-menstruation alternation is not immediate.
Contraceptive reliability
As repeated several times, the Ogino-Knaus method presents a very high probability of failure. It is however necessary to underline that, probably, the contraceptive failure of this strategy is due more to an error in the calculation of fertile days than to an unreliability of the method itself. In fact, especially when the duration of menstrual cycles does not appear to be regular, the calculation of fertile days becomes uncertain and unclear.
The risk of failure of the Ogino-Knaus contraceptive method varies from 16 to 30%.
