This method is probably known to most people who are in a steady relationship. The combination of discontinued intercourse and safe periods are probably used frequently.
How does it work?
If the couple only has intercourse at those times when there is no egg, the woman cannot become pregnant.
Ovulation normally happens 14 days before the next menstruation begins. It can be difficult to know exactly when the woman has her next menstruation. However, if the woman has regular menstruations, it is possible to calculate when she ovulates with the previous menstruation as a starting point – which is known. The egg can only be fertilised four days before and three days after ovulation has taken place and in that period intercourse should be avoided.
Here are two examples of calculating safe periods:
A woman with 24 days between two menstruation will ovulate around (14 subtracted from 24) 10 days after the first day of the last menstruation. The safe periods – where there is no egg to fertilise – are thus from the first day of the last menstruation and 6 days on and from the 13th day after the last menstruation and to the next menstruation (see figure).
A woman with 32 days between two menstruations will have 8 safe periods.
1st day (start of the menstruation)
6th day
24th day
10th day
Ovulation (14 days before next menstruation)
13th day ovulation around (14 subtracted from 32) 18 days after the first day of the last menstruation. Thus, the safe periods are from the first day of the last menstruation and 14 days on and from day 21 after last menstruation and to the next menstruation (see figure)
A woman with 32 days between two menstruations ovulates around (14 subtracted from 32) 18 days after the first day of the last menstruation. Thus, the safe periods are from the first day of the last menstruation and 14 days on and from day 21 after last menstruation and on to next menstruation (see figure).
A tester has been developed that from a test pen and a small monitor can find the periods where intercourse should be avoided. By examining the woman’s morning urine the tester can calculate safe and unsafe days. The tester can be bought at the pharmacy.
Safety
If the method is used correctly – meaning only having intercourse in the safe periods with completely regular menstruating women, calculated by computer – there is 85% chance that the woman does not become pregnant over the course of 12 months.
Disadvantages
• Low safety.
• Does not protect from sexually transmitted diseases.
• You can only have intercourse in certain periods.
Advantages
• The method has no side effects.
• Always available.
• Can be used by everyone