Menstrual cycle

Menstrual cycle

       A wiki link on the subject can be found at:  http://en.wikipedia.org/wiki/Menstrual_cycle

            A sample human get pregnant time graphic follows:

 

The link to the graphic can be found at:  http://en.wikipedia.org/wiki/Calendar-based_contraceptive_methods

Another wiki link on the subject of fertility can be found at:  http://en.wikipedia.org/wiki/Fertility

More precise attempts at calculating when a female might get pregnant can be read about at: 

            http://en.wikipedia.org/wiki/Fertilisation

            http://en.wikipedia.org/wiki/CycleBeads

There are many other links and means on calculating times to get pregnant that exist, too.

 

Even the "pill" has a 2% to 3% failure rate for those practicing birth control using the pill.  In other words, 1 out of 50 times (or more) when a male ejaculates into a female vagina she may get pregnant, depending on many other things, too.