Copper IUDs Linked to Higher Risk for STI Than Hormonal IUDs

Medscape

21-05-2025

MINNEAPOLIS — Copper intrauterine devices (IUDs) are associated with an increased risk for several sexually transmitted infections (STIs) and other vaginal conditions than IUDs containing levonorgestrel, according to a retrospective chart review presented at the American College of Obstetricians and Gynecologists (ACOG) 2025 Annual Meeting.
'Most prior research focuses on bacterial vaginosis and pelvic inflammatory disease risk in IUD users,' wrote Celeste Traub, medical student at the University of Texas Medical Branch in Galveston, Texas, and her colleagues. 'Limited data exist regarding the broader impact of IUDs on other common reproductive tract infections.'
The researchers therefore analyzed data from TriNetX, a group of databases that include information for 56,444,363 patients. They identified 74,219 patients who used the copper IUD without previous use of a levonorgestrel IUD and 451,769 patients who used the levonorgestrel IUD without previous use of a copper IUD. These patients were then matched for age at IUD placement, race, and ethnicity to come up with 73,123 patients in each IUD group. The analysis included only data from within 3 years of IUD placement.
Patients were an average of 30 years old at the time of IUD placement. The cohort included 63.7% White, 21% Hispanic/Latina, 9.9% Black/African American, 5.3% Asian, 0.5% Pacific Islander, and 0.4% Native American patients.
Copper IUDs were associated with a modestly higher risk for chlamydia (risk ratio [RR], 1.41), syphilis (RR, 1.4), gonorrhea (RR, 1.37), and HIV (RR, 1.27) than levonorgestrel IUDs. Copper IUDs were also associated with a higher risk for chronic vulvitis (RR, 1.46), acute vulvitis (RR, 1.41), chronic vaginitis (RR, 1.4), and acute vaginitis (RR, 1.12) than levonorgestrel IUDs.
Risks for anogenital warts, herpes simplex virus 2, candidiasis, and trichomoniasis were not significantly different between copper IUDs and levonorgestrel IUDs. The risk for pelvic inflammatory disease, meanwhile, was lower with the copper IUDs (RR, 0.85) than with the levonorgestrel IUDs.
Despite the large population included, the retrospective design limits what conclusions can be drawn from the findings and there could be unmeasured confounders such as differences in sexual behaviors or socioeconomic factors that affected the results. The study may also have potential selection bias if women who choose different IUD types have different health behaviors.
'These findings highlight the importance of considering vaginal health outcomes when counseling patients about contraceptive outcomes,' the researchers concluded.
'We have thought that one contraceptive mechanism by which hormonal IUDs work is through thickening cervical mucus; this serves as a barrier to sperm,' Hugh S. Taylor, MD, a professor of Ob/Gyn at Yale School of Medicine and chief of Ob/Gyn at Yale New Haven Hospital in Connecticut, told Medscape Medical News . 'It is not surprising that this also serves as a barrier to many STIs.'
He further noted that the study's large size allows the detection of very small differences and highlighted that the risks for any infection with the copper IUD remains small. Further, 'IUDs do not adequately protect against any infection,' Taylor said. 'Barrier methods should be used whenever there is any risk of STI.'
The research was funded by the UTMB Institute for Translational Sciences and the National Institutes of Health. The authors had no relevant financial disclosures. Taylor reported grants to Yale University from AbbVie and Organon unrelated to this research.