go28days is a specialized online calendar designed to help women track menstrual cycles and help predict when to or not to copulate.
From the site description:
In addition to our standard module which enables identification of fertility days in a cycle, go28days can help a woman who has just given birth to monitor when her body is showing signs of fertility. This is important because it takes several days for a woman’s body to recover after giving birth.
Your chart contains only the essential data about your cycle, however you may record some additional information, such as the medication or supplements you take during that time, or anything else you wish to comment on, in a specially designated space. From there you can clearly see how your own notes relate to the chart.
When you first create a chart, customisable access rights allow you to decide who can view your records. Subsequently, you may amend your preferences at any time, in order to limit or extend other users’ access rights.
The greatest advantage of go28days is that it allows every user to independently analyse their own chart. There is no generic formula which calculates when your ovulation or peak fertility will occur. With the help of the analysis forms we provide on our website, you may interpret the signs of your fertile days, temperature surges and luteal phase. Our analysis guide is based on the following methods of cycle interpretation: Billings, Kippley, Roetzer and Double Check.