Intrauterine device use and the risk of pre-eclampsia: a case-control study

ObjectiveTo determine the association between intrauterine device (IUD) use, timing of removal prior to pregnancy, and the risk of pre-eclampsia. DesignA case-control study within the Clinical Practice Research Datalink, UK. SettingMedical record database in the UK. Sample Cases of pre-eclampsia (n = 2744) were identified among pregnancies resulting in singleton deliveries from 1993 to 2010. Four controls, or pregnancies unaffected by pre-eclampsia, were matched to each case on maternal age, general practice, and year of delivery. Methods Data on IUD use were obtained from patient records. The odds ratios (ORs) for the association between IUD and pre-eclampsia were adjusted for covariates identified a priori, and analyses were stratified by BMI and number of prior deliveries. Main outcome measures Odds ratios (95% confidence intervals, 95% CIs) of pre-eclampsia in pregnancies among women with a history of IUD use, compared with women without a history of IUD use. Results Prior IUD use was associated with a reduced risk of preeclampsia (OR 0.76; 95% CI 0.58-0.98). The timing of removal in relation to the start of pregnancy showed an inverse association, with shorter intervals associated with a larger decrease in risk of preeclampsia. IUD removal within a year prior to pregnancy had an OR of 0.68 (95% CI 0.46-1.00). Among women with a prior delivery, the association between IUD use and pre-eclampsia was null. Conclusions Intrauterine device use is associated with a small decreased risk of pre-eclampsia, specifically if removed within the year prior to conception.