Pearl Index

The Pearl Index (named after the American scientist Raymond Pearl) is the measure of the safety of contraceptives: the smaller the Pearl Index, the safer the method of contraception. If 100 women use the same contraceptive for one year and three pregnancies occur during this period, the Pearl Index is 3. A Pearl Index of 0.1 means that one in 1000 women who use the same contraceptive for one year becomes pregnant.

However, the information in the literature is different. Manufacturing studies often quote the Pearl index, which refers to contraceptive safety without errors in usage. Other information, on the other hand, includes some of the application errors. The Pearl Index data can therefore only provide an indication without claiming general validity.

Pearl index of the individual contraceptive methods

• Progestin IUD: 0.16
• Pills: 0.1 – 0.9
• Depot injection: 0.3 – 0.88
• Mini-Pills: 0.5 – 3
• Vaginal ring: 0.4 – 0.65
• Contraceptive patch 0.72 – 0.9
• Copper coil: 0.3 – 0.8
• Hormone implant: 0 – 0.08 / refer to the comments 1
• The Basal temperature method: (only when not having intercourse during the fertile days): 0.8 – 3
• Diaphragm: 1 – 20 / refer to the comments 2
• Condom: 2 – 12
• Cervical cap: 6 / refer to the comments 2, 3
• Female condoms: 5 – 25
• Chemical contraceptives: 3 – 21
• Coitus interruptus: 4 – 18
• No contraception: 85
• Sterilisation of the woman: 0.2 – 0.3
• Sterilisation of the man: 0.1
• Calendar method: 9

Source of the figures:
Guidelines of the German Society for Gynaecology and Obstetrics July 2004, per familia

Comment 1:
Like other big scaled studies, a large Australian study in 2005 estimated the Pearl_Index at around 0.1%, with a large proportion of failures due to an incorrect insertion, in this respect also refer to: Family planning newsletter issue 02/ 2005 page 17

Comment 2:
The information regarding the so-called barrier methods of the diaphragm for women, and contraceptive caps only hold applicable, if used together with a spermicidal gel.

Comment 3:
There are no reliable studies currently available only on the cervical cap in Germany; hence it must be assumed that the safety is similar to that of the diaphragm.