Pearl index

The Pearl Index , named after the American biologist Raymond Pearl (1879–1940), is a measure of the effectiveness and reliability of methods of contraception . It indicates the proportion of sexually active women who become pregnant within a year despite using a certain method of contraception. The lower the Pearl Index, the safer the method.

definition

There are two methods to calculate the Pearl Index:

The first method is based on the months of use (12 months × 100 women):

${\displaystyle {\text{Pearl-Index}}={\frac {{\text{Anzahl Schwangerschaften}}\cdot {1200}}{{\text{Anzahl Frauen}}\cdot {\text{Anwendungsmonate}}}}}$

The second method, on the other hand, relates to the woman's menstrual cycles , so multiply by 1300 since the length of the menstrual cycle lasts on average 28 days (13 cycles):

${\displaystyle {\text{Pearl-Index}}={\frac {{\text{Anzahl Schwangerschaften}}\cdot {1300}}{{\text{Anzahl Frauen}}\cdot {\text{Anzahl der Menstruationszyklen}}}}}$

Example: A Pearl Index of 15 indicates that out of 100 women who use a certain method of contraception for one year, 15 will become pregnant.

Reference values

With regular unprotected sexual intercourse without any form of contraception , the Pearl Index reflects fertility and is around 92 for 19-26 year old women, 86-87 for women between 27 and 34 years and 82 for women between 35 and 39 years of age, depending on age then drops to 0 around the age of 45–50 with the onset of menopause .

Pearl index of the individual contraceptive methods

Contraceptive method	min. Pearl index	Max. Pearl index
No contraception	30th	85
birth control pills	0.1	0.9
Billings Method	5	35
Chemical contraceptives	3	21st
coitus interruptus	4th	18th
Three-month injection	0.3	0.88
Diaphragm	1	20th
Hormone implant	0	0.08
Female condom	5	25th
Hormonal patch	0.72	0.9
Hormonal IUD	0.16	0.16
Calendar method	3	9
condom	2	12
Copper chain	0.1	0.5
Copper spiral	0.3	0.8
Mini pill	0.5	3
Cervical cap	6th	6th
Sterilization of the woman	0.2	0.3
Sterilization of the man	0.1	0.1
Symptothermal method	0.4	2.3
Temperature method	0.8	3
Contraceptive sponge	5	10
Contraceptive ring	0.4	0.65

Comparison of birth control methods (effectiveness)

The table below is color-coded and differentiates between application safety and method safety, with the failure rate being measured as the expected number of pregnancies per year per 100 women using the following method:

blue	less than 1%	lower risk
green	up to 5%
yellow	up to 10 %
orange	up to 20%
red	over 20 %	higher risk
Gray	no data	No data available

In the "User action required" column, elements that are not user-dependent (action required once a year or less) are highlighted in blue. Some methods can be used simultaneously for higher rates of effectiveness, e.g. B. Condoms with spermicides, the estimated method safety would be comparable to the method safety of the implant. However, the mathematical combination of the rates to estimate the effectiveness of the combined methods may be inaccurate because the effectiveness of each method is not necessarily independent, except in the perfect case. If a method is known or suspected to have been ineffective, such as: B. If a condom breaks, emergency contraception can be started within 72 to 120 hours after intercourse. Emergency contraception should be used shortly before or as soon as possible after intercourse, as the delay becomes less effective. Although the morning-after pill is viewed as an emergency measure, levonorgestrel emergency contraception just before sex can be used as the primary method for a woman who only has sex a few times a year and wants a hormonal method but doesn't always want to take hormones . The failure rate of repeated or regular use of emergency levonorgestrel contraception is similar to that of those using a barrier method.

Birth control method	General term	Application security failure rate (%) / (women per year)	Failure rate method reliability (%)	Type	Implementation	User action required
Etonogestrel implant	Implanon , Jadelle	0.05 / (1 of 2000)	0.05	Progestin	Implant	3-5 years
vasectomy	male sterilization	0.15 / (1 of 666)	0.1	sterilization	surgical intervention	unique
Combination injection three-month syringe ( estradiol-17β-cipionate / medroxyprogesterone )	Depo-Clinovir , Noristerat	0.2 / (1 in 500)	0.2	Estrogen and progestin	injection	per month
Hormonal IUD		0.2 / (1 in 500)	0.2	Intrauterine and progestogen	intrauterine	3–7 years
Essure	Sterilization of the woman	0.26 / (1 of 384)	0.26	sterilization	surgical intervention	unique
Ligation of the fallopian tubes	Sterilization of the woman	0.5 / (1 of 200)	0.5	sterilization	surgical intervention	unique
Intrauterine device	spiral	0.8 / (1 of 125)	0.6	copper	intrauterine	3 to over 12 years
Symptom-based fertility awareness	Basal body temperature , cervical mucus	1.8 / (1 of 55)	0.6	Behavior	Observation and schematic representation	Every day
LAM only for 6 months; not applicable if menstruation recurs		2 / (1 of 50)	0.5	Behavior	Breastfeeding	every few hours
Medroxyprogesterone	Three-month injection	3 / (1 of 33)	0.3	Progestogen	injection	12 weeks
Cervical cap and spermicide ( nullipara )		5 / (1 of 20)	No data available	Barrier and spermicide	vaginal	any act of sexual intercourse
Birth control syringe	Testosterone undecanoate	6.1 / (1 of 16)	1.1	testosterone	intramuscular	every four weeks
FemCap and Spermicide (available in the US only)	Cervical cap	7.6 (estimated) / (1 of 13)	No data available	Barrier and spermicide	vaginal	any act of sexual intercourse
Hormonal patch	Contraceptive patch	8 / (1 of 12)	0.3	Estrogen and progestin	transdermal	weekly
birth control pills	pill	9 / (1 of 11)	0.3	Estrogen and progestin	oral medication	Every day
NuvaRing	Contraceptive ring	9 / (1 of 11)	0.3	Estrogen and progestin	vaginal	3 weeks / 1 week break
Mini pill (progestogen only)	POP	9	0.3	Progestin	orally	Every day
Ormeloxifene	Saheli , Centron	9	2	SERM	orally	weekly
Plan B One-Step®	Morning-after pill , active ingredient levonorgestrel	No data available	No data available	Emergency contraceptive pill	orally	after every sexual intercourse
Counting days		12 / (1 of 8.3)	5	Behavior	calendar based	Every day
Cervical cap and spermicide ( Primipara )		15 / (1 of 6)	No data available	Barrier and spermicide	vaginal	any act of sexual intercourse
Diaphragm		16 / (1 of 6)	6th	Barrier and spermicide	vaginal	any act of sexual intercourse
Prentif and Spermicide ( Nullipara )		16	9	Barrier and spermicide	vaginal	any act of sexual intercourse
Today and Spermicide ( Nullipara )	Contraceptive sponge	16	9	Barrier and spermicide	vaginal	any act of sexual intercourse
Latex condom	condom	18 (1 of 5)	2	barrier	placed on erect penis	any act of sexual intercourse
coitus interruptus	natural contraception , intercourse is interrupted	18 / (1 of 5)	4th	Behavior	Pulling out the limb	any act of sexual intercourse
Femidom		21 / (1 of 4.7)	5	barrier	vaginal	any act of sexual intercourse
Knaus-Ogino contraceptive method	Rhythm method	25th	9	Behavior	calendar based	Every day
Spermicidal gel , foam, suppository or film		29 / (1 of 3)	18th	Spermicide	vaginal	any act of sexual intercourse
Contraceptive sponge ( Primipara )		32 / (1 of 3)	20th	Barrier and spermicide	vaginal	any act of sexual intercourse
Prentif and Spermicide ( Parus )	Cervical cap	32	26th	Barrier and spermicide	vaginal	any act of sexual intercourse
None (unprotected intercourse)		85 / (6 of 7)	85	k. A.	k. A.	k. A.
Birth control method	General term	Application security failure rate (%)	Failure rate method reliability (%)	Type	Implementation	User action required

Parameters not taken into account

In the Pearl Index, statistically relevant parameters such as the frequency of sexual intercourse, the size of the sample or a minimum population are not prescribed. As a result, the Pearl Index of new contraceptive methods, as published by interest groups and manufacturers, is often of limited informative value.

The more widespread and long-term a contraceptive method is used, the more precisely the Pearl Index can be specified.

Method security vs. Application security

The safety of most contraceptive methods depends to a large extent on correct use. The cause of failure of contraceptive methods are mostly application errors. Therefore, method security , i.e. failure despite optimal application, and application security , i.e. the practical consideration of application errors, are significantly different for most methods. The Pearl Index of many methods also depends on the user, in particular on his level of knowledge and experience as well as his reliability and motivation. Depending on the study, the Pearl Index can therefore fluctuate significantly.

Remarks

1. ↑ The term fertility awareness is sometimes used interchangeably with the term natural family planning (NFP), although NFP normally denotes the periodic renunciation in accordance with the faith of the Catholic Church .
2. ↑ The pregnancy rate applies up to six months after giving birth or until menstruation resumes, whichever comes first. If menstruation begins six months after giving birth, this method is no longer effective. For users of this method who do not menstruate before the end of six months after giving birth, the following applies: After the six months this method is less effective.
3. ↑ In the Lea's Shield efficacy study , 84% of the participants were para . The unadjusted pregnancy rate in the six-month study was 8.7% in the spermicide users and 12.9% in those who did not use spermicide. No pregnancy occurred in the Nullipara with Lea's Shield . Assuming the nulliparous to Para efficacy ratio for Lea's Shield is the same as for the Prentif cervical cap and the Today contraceptive sponge, the unadjusted six-month pregnancy rate would be 2.2% for spermicide users and 2.9% for those who used the contraceptive without spermicide.

Individual evidence

1. ↑ ^{a b c d e f g h i j k l m n o p q r} Pearl index. pro familia, accessed December 27, 2016 . 
2. ^ Elisabeth Raith-Paula, Petra Frank-Herrmann, Günter Freundl, Thomas Strowitzki: Natural family planning today. Modern cycle knowledge for advice and application. Springer, Berlin, Heidelberg 2013, ISBN 978-3-642-29783-0 , pp. 164-165 .
3. ↑ https://journals.lww.com/greenjournal/Fulltext/2004/01000/Increased_Infertility_With_Age_in_Men_and_Women.10.aspx
4. ↑ ^{a b c d} James Trussell: Contraceptive Technology . Ed .: Robert A. Hatcher, James Trussell, Anita L. Nelson. 18th edition. Ardent Media, New York 2004, ISBN 0-9664902-6-6 , Contraceptive Efficacy, p. 773-845 .
5. ↑ ^{a b} Better than nothing or savvy risk-reduction practice? The importance of withdrawal . Contraception. December 2009. Retrieved May 21, 2019.
6. ↑ ^{a b c d e f g h i j k l m n o p q r s t u} James Trussell: Contraceptive Technology . Ed .: Robert A. Hatcher, James Trussell, Anita L. Nelson. 19th edition. Ardent Media, New York 2007, ISBN 0-9664902-0-7 , Contraceptive Efficacy ( contraceptivetechnology.org ).
7. ↑ I. Sivin, I. Campodonico, O. Kiriwat, P. Holma, S. Diaz, L. Wan, A. Biswas, O. Viegas, K. El Din Abdalla: The performance of levonorgestrel rod and Norplant contraceptive implants: A 5 year randomized study . In: Human Reproduction . 13, No. 12, 1998, pp. 3371-8. doi : 10.1093 / humrep / 13.12.3371 . PMID 9886517 .
8. ↑ FDA Approves Combined Monthly Injectable Contraceptive . Contraception online. June 2001. Archived from the original on October 18, 2007. Retrieved on April 13, 2008.
9. ↑ Essure System - P020014 . United States Food and Drug Administration Center for Devices and Radiological Health. Archived from the original on December 4, 2008.
10. ↑ Lea's Shield doi: 10.1016 / 0010-7824 (96) 00081-9
11. ↑ ^{a b} Multicenter Contraceptive Efficacy Trial of Injectable Testosterone Undecanoate in Chinese Men . In: The Journal of Clinical Endocrinology & Metabolism . tape 94 , no. 6 , 2009, ISSN  0021-972X , p. 1910-1915 , doi : 10.1210 / jc.2008-1846 ( oup.com ).
12. ^ Clinician Protocol . FemCap manufacturer. Archived from the original on January 22, 2009.
13. ↑ ^{a b c} http://www.contraceptivetechnology.org/wp-content/uploads/2013/09/CTFailureTable.pdf
14. ^ Puri V: Results of multicentric trial of Centchroman . In: Dhwan BN et al. (Ed.): Pharmacology for Health in Asia: Proceedings of Asian Congress of Pharmacology, January 15-19, 1985, New Delhi, India . Allied Publishers, Ahmedabad 1988. Nityanand S: Clinical evaluation of Centchroman: a new oral contraceptive . In: Chander P. Puri, Paul FA Van Look (Ed.): Hormone Antagonists for Fertility Regulation . Indian Society for the Study of Reproduction and Fertility, Bombay 1990.