Effects of intrauterine contraception on the vaginal microbiota

There have been conflicting reports of altered vaginal microbiota and infection susceptibility associated with contraception use. The objectives of this study were to determine if intrauterine contraception altered the vaginal microbiota and to compare the effects of a copper intrauterine device (Cu-IUD) and a levonorgestrel intrauterine system (LNG-IUS) on the vaginal microbiota.

DNA was isolated from the vaginal swab samples of 76 women using Cu-IUD (n=36) or LNG-IUS (n=40) collected prior to insertion of intrauterine contraception (baseline) and at 6 months. A third swab from approximately 12 months following insertion was available for 69 (Cu-IUD, n=33; LNG-IUS, n=36) of these women. The V4 region of the bacterial 16S rRNA-encoding gene was amplified from the vaginal swab DNA and sequenced. The 16S rRNA gene sequences were processed and analyzed using the software package mothur to compare the structure and dynamics of the vaginal bacterial communities.

The vaginal microbiota from individuals in this study clustered into 3 major vaginal bacterial community types: one dominated by Lactobacillus iners, one dominated by Lactobacillus crispatus and one community type that was not dominated by a single Lactobacillus species. Changes in the vaginal bacterial community composition were not associated with the use of Cu-IUD or LNG-IUS. Additionally, we did not observe a clear difference in vaginal microbiota stability with Cu-IUD versus LNG-IUS use.

Although the vaginal microbiota can be highly dynamic, alterations in the community associated with the use of intrauterine contraception (Cu-IUD or LNG-IUS) were not detected over 12 months.

We found no evidence that intrauterine contraception (Cu-IUD or LNG-IUS) altered the vaginal microbiota composition. Therefore, the use of intrauterine contraception is unlikely to shift the composition of the vaginal microbiota such that infection susceptibility is altered.