That fact explains why any woman who hopes to become pregnant should pay increased attention to her menstrual cycle. The length of her cycle offers important clues about when she will ovulate. The information about the expected time of ovulation serves to pinpoint the days when she will have the greatest chance of becoming pregnant. She can mark those days on the calendar.

The development of a fertility or ovulation calendar can not take place overnight. In fact, it can not take place over the course of one month. The development of a fertility or ovulation calendar requires a woman's attention to her menstrual cycle for a period of 8 to 12 months.

During month number one a woman should mark down the first day of her period. That represents Day 1. The woman should then count how many days pass until the start of the next period. That is the length of her menstrual cycle for the first month. That cycle length must then be compared to the cycle length for the each of the next 8 to 12 months.

A woman who hopes to become pregnant wants to know when she should expect to be most fertile. In order to make that determination, a woman must look for the month when her cycle had the fewest number of days. She should count the number of days in that shortest cycle, and then she should subtract 18 from that day count.

A woman can then use that difference to determine the most fertile days in her next menstrual cycle. She knows that Day 1 is the day when her period starts. If she counts ahead 18 plus the difference mentioned in the above paragraph, then she will find her finger on the first day when she should exhibit maximum fertility.

During the approaching month, what day should the same woman mark on the calendar as the last day when she will be fertile? That can be calculated by finding the length of the longest cycle during the past 8 to 12 months. The woman then needs to subtract 11 from the "longest cycle" count.

A new subtraction gives a new difference. A woman can then mark off on the calendar 11 days plus that calculated difference. The woman must recall that she will count the first day of her period as Day 1. In that way, any woman has the ability to find the last day when she will exhibit the maximum fertility.

Once a woman finds the day of her expected ovulation, she will want to check for evidence of ovulation. That can be done with an FDA approved ovulation test, with observation of the cervical mucus or with careful attention to the basal body temperature for many months.