Six cohort studies and seven case-series were included. Four cohort studies (n=1,489 women) and four case series (n=643 women) appeared to provide most of the results data. Number of women in the other studies was not reported. Duration of follow-up ranged from six to 48 months.
Continuation of IUD use (seven studies): Continuation rates were mostly high at one year and decreased after this. Rates at 12 months ranged from 48% to 88%. Rates at 24 months ranged from 49% to 73%. Rates at 36 months ranged from 39% to 45%. One study reported a rate of 31% at 48 months. Two controlled studies reported similar continuation rates for IUDs and combined oral contraceptives (n=112 with IUD and n=162 with combined oral contraceptives).
Pregnancy rates (seven studies): Cumulative pregnancy rates increased from 2% at six months to 11% at 48 months. One study reported pregnancy rates at 48 months of 3% for IUDs versus 0% for combined oral contraceptives (n=30 with IUD and n=72 with combined oral contraceptives).
IUD expulsion (seven studies): Expulsion rates varied widely from 5% to 22% over periods that ranged from six to 48 months. Two studies reported lower rates with increasing age; no consistent relationship to parity was identified.
Pelvic inflammatory disease (three studies): The authors stated that it was not possible to interpret the reported outcomes due to different definitions of genital tract infection.
Pain at insertion: One study with insertion of experimental W, LEM IUD and Lippes loop C and D in predominantly nulliparous women (devices no longer used at the time of the review). Severe pain was reported by 14% of women, moderate pain by 23% and minimal or no pain by 63%.
Removal for bleeding or pain (three studies): Removal rates were higher in adolescents compared to parous adults (one study). Rates were similar for adolescents and older women in another study). Bleeding was more common with IUDs than combined oral contraceptives (one study).