If you are interested in the topic "fertility calender and achieving pregnancy", the following paragraphs might contain some useful information.
On a lot of web pages, fertility calendars are supplied which can be used by women to determine their fertile days and achieve pregnancy.
Normally, these fertility calendars work as follows: The woman has to enter the first day of her last period as well as the normal duration of her cycle into the appropriate fields. Then, her fertile days will be evaluated for the next month(s). Mostly, the fertile days are emphasized somehow and are divided into fertile days and very fertile days until the ovulation.
In order to achieve pregnancy, the couple should have sexual intercourse around the point of time when the ovulation takes place. The highest possibility for a conception is during the ovulation and in the following 18 hours. The probability of getting pregnant during this time is three times higher than during the other 5 of the fertile days.
Of course, there is no guarantee of achieving pregnancy just by having sexual intercourse during the fertile days of a woman, as the fertility of a woman (as well as of a man) is also dependent on various other factors, e.g. age, life-style, health, nutrition.
1.) Age
Whereas a young, healthy woman who is 20 years old, generally only needs to wait 2 1/2 months until she successfully conceives, women at the age of 40 approximately have to wait 2 years. A decreasing fertility by age can also be observed in men. In comparison to an 18-year-old, the sperm quantity of a 45-year-old is reduced about a third, and the number of viable sperms about 50%.
2.) Life-style, health, nutrition
It is common knowledge that couples with a healthy life-style (avoidance of stress, alcohol, drugs, cigarettes) achieve pregnancy easier than couples who lead an unhealthy life.