Calendar

避孕

避孕方法:女性避孕方法: 安全期避孕

日期計算法
第二個推算“不安全的”日期的做法在於保存至少8個月的月經週期記錄。利用這種日曆記錄，挑選出最長月經週期和最短月經週期。然後用最短週期的天數減18，即為現在月經週期“不安全的”第一天；進而用最長週期天數減去11，即為現在月經週期“不安全的”最後一天。舉例來說，如果最短週期是25天，那麼25-18=7(其現在的月經週期“不安全的”第一天是月經後第7天)；如果其最長週期是31天，則31-11=20(其現在的月經週期“不安全的”最後一天為月經後第20天)。

最短週期 Shortest cycle		週期開始後的第一個不安全日 First unsafe day after beginning of cycle	最長週期 Longest cycle		週期開始後的最後一個不安全日 Last unsafe day after beginning of cycle
21 days	-18 =	3rd day	21 days	-11 =	10th day
22 days	-18 =	4th day	22 days	-11 =	11th day
23 days	-18 =	5th day	23 days	-11 =	12th day
24 days	-18 =	6th day	24 days	-11 =	13th day
25 days	-18 =	7th day	25 days	-11 =	14th day
26 days	-18 =	8th day	26 days	-11 =	15th day
27 days	-18 =	9th day	27 days	-11 =	16th day
28 days	-18 =	10th day	28 days	-11 =	17th day
29 days	-18 =	11th day	29 days	-11 =	18th day
30 days	-18 =	12th day	30 days	-11 =	19th day
31 days	-18 =	13th day	31 days	-11 =	20th day
32 days	-18 =	14th day	32 days	-11 =	21th day
33 days	-18 =	15th day	33 days	-11 =	22th day
34 days	-18 =	16th day	34 days	-11 =	23th day
35 days	-18 =	17th day	35 days	-11 =	24th day
36 days	-18 =	18th day	36 days	-11 =	25th day
等等/etc.			等等/etc.

Contraception

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

Calendar
A second way of finding the "unsafe" days consists in keeping a calendar record of menstrual cycles for at least eight months. Using this calendar record, a woman selects her longest and her shortest cycle. She then subtracts 18 days from her shortest cycle to find the first "unsafe" day of her present cycle. She further subtracts 11 days from her longest cycle to find the last "unsafe" day of her present cycle. For example, if her shortest cycle is 25 days, then 25 - 18 = 7 (the seventh day is the first "unsafe" day of her present cycle): If her longest cycle is 31 days, then 31-11= 20 (the twentieth day is the last "unsafe" day of her present cycle).

[Course 2] [Description] [How to use it] [Introduction] [Conception] [Pregnancy] [Birth] [Infertility] [Contraception] [A Complex Issue] [Methods of Contracep.] [Abortion] [Additional Reading] [Examination]