Women that have undiagnosed sexually transmitted infections (STIs) may be at greater risk of experiencing negative premenstrual syndrome (PMS) symptoms, according to new Oxford University research.

The study was conducted as part of a long-term partnership with the female health, fertility, and period-tracking app, CLUE. The findings, published in Evolution Medicine & Public Health, suggest that the presence of an undiagnosed STI might aggravate the negative premenstrual experience.

Despite being known to have an antisocial effect on women’s lives, altering their moods, energy levels, eating habits, and even sex drive, periods are not recognized as a scientific factor in the study of female health. However, since some STI infections are asymptomatic, for instance 70% of people diagnosed with chlamydia are unaware of it, and can lead to fertility issues, the study authors caution that these results are significant, and that reproductive health needs to be taken more seriously by both the scientific community and women in general.

Dr. Alexandra Alvergne, lead author and associate professor of anthropology at Oxford University, said: "Even now, when I write a research application on PMS, I still think ‘will this be taken seriously?’—that needs to change. Not understanding or even acknowledging that PMS is more than ‘women’s raging hormones’ but rather, the byproduct of cyclical immunity, makes it harder to identify diseases and can even delay diagnosis of infections such as STIs, which can affect women’s fertility."

The digital health study used data from 865 CLUE app users, who were asked whether they had ever been diagnosed with an STI, and if they answered yes, when they were first diagnosed and given treatment.

This information was combined with data that they had logged on their menstrual bleeding patterns, experience of pain and emotional impacts, and whether or not they used hormonal contraceptives.

Before diagnosis, the presence of an infection, such as chlamydia, herpes, or HPV, doubled the likelihood of the woman reporting negative PMS effects, including headaches, cramps, and sadness towards the end of their cycle, and generally feeling highly sensitive throughout.

The findings from this work will also be used to improve the CLUE app, and shape additional questions that would make the overall data captured more robust and useful.

Dr. Alvergne said: "Our research shows that by better understanding their period and menstrual cycle, women could potentially improve their health. If you know that severe PMS could be an indicator of an underlying STI, you are more likely to listen to your body."

In addition to better understanding the relationship between women’s sexual and menstrual health, the team’s review of academic research published to date on PMS has revealed a direct link between menstrual cycling and women’s overall physical health and well-being.

The accumulative review, published in Trends & Ecology & Evolution, reveals that the severity of chronic inflammatory diseases or the risk of infection depends on the phase of the menstrual cycle women are experiencing.

It asserts that the menstrual cycle modulates the immune system so that to select viable embryos, so is itself a cycle of immunity.

Dr. Alvergne said: "The whole function of the menstrual cycle is to produce cyclical patterns of immunity, so actually we would be better to think of female health as cyclical. To truly understand women’s health we need to better understand reproductive health, as the two go hand in hand."