How to Calculate Safe Period and Danger Period?

Safe Period Time Calculation Method and Chart

Safe Period /Rhythm Method/Calendar Method:

It is that period of menstrual cycle during which there is least chance of fertilization in spite of frequent coitus due to absence of ovum. It is the sterile period in each menstrual cycle during which conception does not occur.

Calculation Method of Safe Period Time:

A. In a regular menstrual cycle (28 days):

• 28- 18= 10th day is the 1st day of the fertile period (First unsafe day),
• 28 -10= 18th day is the last day of the fertile period (Last unsafe day).

So the total unsafe days are from 10th to 18th day of the menstrual cycle = 9 days only. All other days before and after the unsafe days are the safe period.

B. In an irregular menstrual cycle (26 to 31 days):

• 26- 18 = 8th days is the first day of the fertile period (First unsafe day),
• 31- 10= 21st day is the last day of the fertile period (Last unsafe day).

So the total unsafe days are from 8th to 21st day of the menstrual cycle = 14 days. All other days before and after the unsafe days are the safe period.

Key Factors of Safe Period Time:

Safe period is based on the following facts:

1. Only Ovum is discharge in each cycle which survives for 24-48 hours.
2. Spermatozoa survive 48-72 hours after ejaculation.
3. Ovulation usually takes place on the 14th days prior to the onset of next menstruation with a ±2 day’s variation on either side i.e. ovulation occurs from 12th to 16th days prior to the onset of menstruation.
4. For above reasons there are only 3 days for conception in each menstrual cycle. If the sexual intercourse is restricted for these 3 days conception will not occur. The beginning of the fertile period can be estimated by subtracting 18 days (16 days + 2 days sperm survival) from the shortest cycle. The end of the fertile period can be estimated by subtracting 1 0 days (12 days -2 days ovum survival) from the length of the longest cycle.

Is Safe Period 100% Safe?

No, safe period is not 100% safe due to the below reasons-

• A woman’s menstrual cycles are not always regular if the cycles are irregular it is different to predict the safe period.
• There may be wrong calculations inability to follow calculations irregular use and taking chances.
• Spermatozoa can live up to 7 days in exceptional couples.

More questions related to this article?

1. What is a woman’s safe period?
2. What is calendar method?
3. What is rhythm method?
4. What is danger period?
5. How many days before and after a period is safe?
6. How many days is a safe period?
7. What is a safe cycle for a period?
8. What are the safe days of a woman after periods?
9. What are the safe days in menstrual cycle?
10. What are the factors of safe period?