UCSF

Objective

Understanding the effect of contraceptives on the development of precancerous lesions of the cervix and cervical cancer may provide information that is valuable to women in contraceptive decision-making. The purpose of this study was to evaluate the association between recent intrauterine device (IUD) use (by type) and cervical intraepithelial neoplasia 2, 3, adenocarcinoma in situ or cancer (CIN2+ or CIN3+).

Study design

Case-control study of 17,559 women age 18-49 with incident CIN2+ cases and 5:1 age-matched, incidence-density selected controls (N=87,378) who were members of Kaiser Permanente Northern California Healthcare System from 1996 to 2014. Recent IUD use, within 18 months prior to index, was the exposure of interest.

Results

We identified 1,657 IUD users among the cases and 7,925 IUD users among controls. After adjusting for sexually transmitted infection testing, smoking, HPV vaccination, hormonal contraceptive use, parity, race and number of outpatient healthcare system visits, IUD use was associated with an increased rate of CIN2+ [rate ratio (RR) 1.12, 95% confidence interval (1.05-1.18), p<0.001] but not CIN3+ [RR 1.02 (0.93-1.11), p=0.71]. Levonorgestrel-IUD use was associated with an increased rate of CIN2+ [RR 1.18 (1.08-1.30), p<0.001] but not CIN3+ [RR 1.05 (0.91-1.21), p=0.48]. Copper-IUD use was not associated with CIN2+ [RR 0.88 (0.75-1.04), p=0.13] or CIN3+ [RR 0.81 (0.64-1.02), p=0.07].

Conclusion

Recent IUD use had variable weak associations with CIN2+ but was not associated with increased risk of CIN3+.

Implications

Recent levonorgestrel-IUD use may be associated with CIN2, a lesion with a high rate of regression, but not CIN3, which is considered a true pre-cancerous lesion. The observed association between levonorgestrel-IUDs and CIN2+ was modest but warrants further investigation. It may have clinical importance for contraceptive counseling if this finding is shown to be consistent across other studies and other populations.