基础体温法
为了至少得到那么一点安全期避孕的确定性，可以运用两种不同的策略（实行安全期避孕的许多妇女实际上同时运用这两种策略）：第一，在每天早晨起床前用特殊的体温计（一般为口含式体温计——译者注）量本人的体温，所得到的体温叫基础体温（basal temperature）。在每次排卵前，基础体温有轻度的下降，在随后的月经周期的其余日期，基础体温则轻度上升。在决定采用安全期避孕时，通过比较至少6个月前的基础体温记录，可以计算下一次月经周期的排卵时间。第二个推算“不安全的”日期的做法在于保存至少8个月的月经周期记录。

Contraception

Methods of Contraception: Contraceptive Methods for Women）: “Rhythm”

Basal Temperature
In order to gain at least some certainty, a woman can use two different strategies (and many women who practice the "rhythm method" actually use both at the same time): First, she can take her body temperature with a special thermometer every morning before getting out of bed. This is called the basal temperature. Before each ovulation, there is a slight drop in body temperature followed by a slight rise for the rest of the menstrual cycle. By comparing her temperature-records of at least six previous months, the woman can calculate the time of her next ovulation. A second way of finding the "unsafe" days consists in keeping a calendar record of menstrual cycles for at least eight months.