Did you know that the use of copper intrauterine devices (Cu-IUDs) has been associated with an increased acquisition of bacterial vaginosis (BV)? A study conducted on 266 participants found that the prevalence of BV in women using Cu-IUDs increased from 27% to 49% after 6 months. This increase was not observed in women using hormonal methods of contraception. It was found that Cu-IUDs contribute toward an increase in the concentration of bugs responsible for the development of BV, namely Gardnerella vaginalis and Atopobium vaginae (1).
Vaginal microbiome changes after application of Cu-IUD: Increase of BV positive participants with time, correlates with increase in concentration of G. vaginalis and A. vaginae. Data taken from Achilles et al., 2018.
What is an IUD (intrauterine device)?
IUDs are devices which serve as a contraceptive. Contraceptives are used to prevent unintended pregnancies and can function through mechanical or hormonal means. In the United States, approximately 65% of women aged 15 to 49 use some form of contraception. Nearly all sexually active women in the USA have used a form of contraception at some point in their lives (2).
One of the contraception methods is the intrauterine device (IUD). The application of an IUD is a non-permanent method of contraception. IUDs can be either hormonal or non-hormonal. In this article, we seek to explore the scientific evidence regarding the interaction and influence of IUDs on the vaginal microbiome, a critical component of vaginal and reproductive health. The table below lists all contraceptive methods and describes their prospective influence on the vaginal microbiome.
Contraceptives and their interaction with microbiome
As confirmed in the Scientific Review (3), it has been generally found that all women who use IUDs may have an increased prevalence of bacterial vaginosis (BV) compared to those who do not use IUDs.
Adapted from Bakus et al., 2023.
Copper T intrauterine devices (Cu-IUDs)
Copper T intrauterine devices (Cu-IUDs) are non-hormonal metal IUDs. Once placed in the uterus, they can remain effective as contraceptives (99% of the time) for up to 10 years. The interaction and influence of Cu-IUDs on the vaginal microbiome remain controversial.
Interestingly, it was found that Cu-IUD does not affect the healthy microbiome, namely lactobacilli colonies. So, if healthy bacteria are not affected, why does BV increase after the implantation of a Cu-IUD? There are a few explanations for why Cu-IUDs might increase BV.
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Firstly, the increased presence of a foreign object may promote the colonization of BV-associated bacteria, such as Gardnerella vaginalis. However, this reaction is not seen with other hormonal-based IUDs, so there must be more to it than just the presence of a foreign object—likely related to the release of copper.
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Cu-IUDs can also cause an increased volume and duration of menstruation. The increased blood flow makes iron-containing protein compounds in red blood cells more available, which promotes the growth of BV-associated bacteria (6).
On the other hand, there are other studies showing that Cu-IUDs are not associated with higher BV prevalence. For instance, a study conducted on 137 Thai women divided them into four groups: HIV-positive with Cu-IUD, HIV-positive without Cu-IUD, HIV-negative with Cu-IUD, and HIV-negative without Cu-IUD. Interestingly, there were no statistically significant differences in BV prevalence between these groups. Moreover, BV prevalence was not related to either HIV status or Cu-IUD use; instead, it was related to Body Mass Index (BMI), with women with a BMI < 20 showing higher BV prevalence (7). Similarly, a study conducted in the USA found that shifts and changes in the vaginal microbiome over a 12-month period were completely unrelated to either Cu-IUD or Levonorgestrel-IUD application. There could be a few reasons for such an outcome. The study involved women from different ethnic backgrounds, resulting in a high level of diversity in vaginal microbiome community types. Additionally, the vaginal microbiome composition was monitored at six-month intervals, which may not capture changes occurring within shorter time periods (8).
Decision time
Despite differing findings in clinical studies, you may still be weighing your contraception options. We recommend discussing with your healthcare practitioner the most suitable contraception method for your age, hormonal balance, overall health status, and individual circumstances.
If you have problems or concerns with your IUD, consult your healthcare practitioner—never attempt to remove an IUD yourself.
If you are already using an IUD, be aware of symptoms that may indicate your vaginal microbiome is out of balance, such as unusual odour, and changes in discharge consistency, quantity, or colour.