According to the books, Ovulation (most fertile period) happens on the 14th day of the cycle (usually on a 28 days cycle).
Lets say your girl starts her menstruation (first day of "Red days") on October 1. Her most fertile period would be between 14th - 15th.
In order to impregnate, a sperm cell must be in contact with a egg cell. Why is this important? Here.
-The Viability (time a cell can live) of a sperm cell inside the super acidic vagina is 3-4 days, some says up to 5. Meanwhile a released egg will only live up to 24 hours,and it is released on the 14th day (most fertile period) if not fertilized (invaded by a sperm) will degrade and become dirt included in the messy uber lansa na mens. LOL.
Conclusion
You can have unprotected sex from day 1(kung trip mo to) up to day 8.
why up to 8th day only? because your sperm can live 3-5 days inside, ayaw mo naman putukan on the 9th then magrerelease ng egg on the 14th, there is still a chance although slim na.
Then you continue from day 19 (i use this, para sure na negative. even though viability of an egg is only 24 hours. i use 72 hours safe time. lol.) up to day 28th.
Disclaimer : This is not an exact science, in fact nothing is. But these are according to books, and books are according to researches and journals, and researches and journals are based on true life experiments. So id say this is true. LOL
Have fun!
