PID associated with fertility regulating agents. Task Force on Intrauterine Devices, Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization.

A WHO sponsored matched case-control study to examine the association between acute pelvic inflammatory disease (PID) and contraceptive use was conducted in 8 developing country and 4 developed country centres. 608 cases of acute febrile non-postpartum PID were individually matched with 1216 controls; 437 of the cases came from centres in developing countries and 171 from developed country centres. Among parous women the relative risks of a first episode of PID associated with current IUD use were 2.3 in developing and 4.1 in developed country centres. Nulliparous women in developed countries had a relative risk of 11.5, but the risks could not be estimated for nulliparous developing country women because there were insufficient IUD users. The high risk among nulliparous women was in part due to bias arising from probable differences in sexual activity in unmarried cases and controls. The risks for parous women aged 15-24 were 9.1 in developed and 2.9 in developing country centres. The risks of PID associated with current IUD use were much higher in women with a past history of PID. An increased PID risk was also found with past IUD use. Use of oral contraceptives or conventional contraceptives was associated with a reduced risk of first episode PID in parous but not in nulliparous women. Irrespective of contraceptive use, a past history of PID increased the risk of recurrent infection, and abortion was associated with an increased risk of first episode and recurrent PID. In conclusion, except for women under 25, the present study showed similar risks of PID related to contraceptive use, past infection or abortion in parous women from developed and developing country centres.