A comparative controlled trial in rural Thailand of three intrauterine devices

Abstract

A controlled comparative trial of three intrauterine devices (the Lippes loop C, Antigon-F and Ypsilon devices), was undertaken in a rural area of Thailand. 2,452 insertions were performed, and a two-year follow-up period provided 2,946.4 woman-years of observation. The three treatment groups were fully comparable in terms of age, parity, open birth interval, previous contraceptive use and haematocrit level. Life table analysis showed that the Antigon-F had significantly lower expulsion rates than the other two devices, and that the Lippes C was associated with the highest risk of expulsion. The expulsion rates after two years were higher than has been generally reported in the literature (16.2, 31.8 and 25.1 per 100 women for the Antigon-F, Lippes C and Ypsilon, respectively). However, differences in the characteristics of the study populations, ethnic factors and follow-up procedures could explain this finding. The pregnancy rates were comparable for all three devices and in general the removal rates were also comparable. The Antigon-F had significantly higher continuation rates than the other two devices through 18 months. However, there was no significant difference in continuation rates between the three devices after two years of observation. Considerable variation was noted in the event rates for different insertion personnel.