Use of IUD and subsequent fertility--follow-up after participation in a randomized clinical trial

Although the IUD has been a contraceptive method for about 50 years, how it affects subsequent fertility remains controversial. The aim of our study was to examine time to pregnancy, pregnancy outcome and the need for infertility workup in a cohort of previous copper IUD users.

From May 1993 to April 1995, 957 women were included in a prospective cohort IUD study in the city of Trondheim, Norway. From this randomized clinical trial, we identified 205 women eligible for study participation. Group A comprised 109 women who removed their IUD for purposes of planning to become pregnant, while Group B comprised 96 women who became pregnant or planned pregnancy after a complicated IUD use. Data were collected through a postal questionnaire. All information from the questionnaires was validated against data kept in the medical record at the general practitioner's office or in the hospital record of women who became pregnant or started an infertility workup. All analyses were done using SPSS.

In Group A, 93.6% (102/109) of the women became pregnant. Time to conception was unaffected by parity order, duration of use and age at time for removal of the IUD. Among the seven women who did not conceive, four women cancelled pregnancy plans, while three women started an infertility workup. The distribution of intra-/extrauterine pregnancies did not differ between Groups A and B. However, significantly more pregnancies were terminated as induced abortions in Group B. The two women (2%) who did not conceive in Group B did not start an infertility workup.

In line with results from other studies, there is no evidence that prior use of a copper-containing IUD increases the risk for impaired fertility regardless of the reason for removal.