Chapters
- Background
- IUD Performance
- Insertion
- Removal
- Infection
- Worldwide Use
- IUDs in Family Planning Programs
HIGHLIGHTS
Published by the Population Information Program,
Center for Communication Programs, The Johns Hopkins School of Public Health,
111 Market Place, Suite 310, Baltimore, Maryland 21202-4012, USA
Volume XXIII, Number 5
December 1995 |
PID and IUD Use
Epidemiologic research in the 1970s and early 1980s tended
to overestimate the risk of pelvic infection from IUD use. These
studies reported that IUD users were up to 10 times more likely
to develop PID than other women (219). Several factors account
for the initial overestimate, including:
- In most early studies the comparison group included women
using oral contraceptives and barrier methods—methods that
protect against PID.
- The risks for specific types of IUDs, particularly the
Dalkon Shield, were not analyzed separately. The higher risk
with the Dalkon Shield inflated overall risk estimates for
all IUDs (627).
- Many studies did not take into account a number of important
factors that affect the risk of PID—age, number of sexual
partners, and history of PID (437, 521).
Three large studies published since the early 1980s have
taken these earlier problems into account and found a lower risk.
The US Women's Health Study found that IUD users were 1.6 times
as likely to be hospitalized for PID as women using other methods
or no method (41). In the Oxford University/Family Planning
Association cohort study, the relative risks were 1.8 for women
using medicated (mostly copper) IUDs and 3.3 for women using
inert IUDs (495). A WHO study in 12 countries found that in
developing countries IUD users with children were 2.3 times more
likely to develop PID than women using no contraception. The
relative risk for similar women in developed countries was 4.1
(446). A reanalysis of data from 13 WHO clinical trials found
that the incidence of PID among IUD users dropped substantially
after 1980. The PID rate among women who had IUDs inserted after
1980 was less than half that among women who had earlier
insertions (507). The decrease may have occurred because
participants in the later studies faced less exposure to STDs.
Although IUD users are more likely to develop PID than nonusers, it
is still an uncommon complication. A WHO study of multiparous women, mostly
in developing countries, who were using copper IUDs reported a cumulative
rate of removal for PID of less than one per 100 women after six years
of use (307). Another international multicenter study reported 3.4 removals
of copper IUDs per 100 women after seven years of use (549). In a European
study involving many young, unmarried women, who are at higher risk for
PID, the 5-year removal rate was seven per 100 women (226)
(see Table 1).
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