London, Sep 18: Women who have undiagnosed sexually transmitted infections may be at greater risk of experiencing negative premenstrual symptoms (PMS), such as headaches, cramps and sadness, an Oxford study has found.

Despite being known to have an anti-social effect on women's lives, altering their moods, energy levels, eating habits and even sex drive, periods are not recognised as a scientific factor in the study of female health.

However, some sexually transmitted infections (STIs) are asymptomatic and can lead to fertility issues. For instance, 70 per cent of people diagnosed with Chlamydia is unaware of it.

The researchers from Oxford University in the US said that reproductive health needs to be taken more seriously by both the scientific community and women in general.

"Not understanding or even acknowledging that PMS is more than 'women's raging hormones' but rather the by-product 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," said Alexandra Alvergne, lead-author at Oxford University in the UK.

The study used data from 865 users of a period-tracking app, CLUE, who were asked whether they had ever been diagnosed with an STI, and if we're given treatment.

This information was combined with data that they had logged on their menstrual bleeding patterns, the 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, published in Evolution Medicine & Public Health, will also be used to improve the CLUE app and shape additional questions that would make the overall data captured more robust and useful.

"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," said Alvergne.