Research published in online journal BMJ Open shows that menstrual symptoms like pain and heavy flow are causing women to lose around nine days of productivity at work each year.

The study was the largest of its kind, surveying 32,748 Dutch women aged between 15 and 45 years. The participants were asked to fill in a comprehensive questionnaire about their menstrual cycle and the severity of their associated symptoms, evaluating them with a validated pain score. They were also asked if and how often these symptoms had caused them to miss work or school and whether it had affected their productivity whilst working or studying.

Nearly a third (31%) of the women had been to their doctor about their menstrual symptoms and one in seven had been to see a gynaecologist. Just under 14% of respondents said that they had taken time off from work or school during their period. Nearly 3.5% said that this occurred during every, or almost every, cycle. This averaged at one day of absence every year. Women under the age of 21 years were far more likely than older women to say that they had taken time off.

Results of the study suggest that stigma, or perhaps a fear that symptoms would not be taken seriously, still exists. Only one in five participants told their employer or school the real reason for their absence.

The majority of women (around 81%) reported presenteeism - going to work or school whilst dealing with these symptoms - and said they were less productive as a result. Researchers calculated that women were less productive for around a third of the time because of menstrual symptoms. Overall, total lost productivity amounted to nine days off as productivity was substandard on 23 days a year. Translated into worldwide statistics, this amounts to a massive amount of lost time and highlights a need for more understanding of menstrual symptoms.

Theodoor Nieboer, a co-author of the report and a gynaecologist in the Netherlands, explained in a comment for CNN that reasons women may have been less productive during their period included that they needed "to go to the toilet every hour or they had a headache and couldn't concentrate". He stressed that there were also "plenty of reasons why men might be unproductive in the workplace".

Offering more flexible work or study hours during a period was viewed as a popular solution by around two thirds of participants. Some countries in Asia already offer women menstrual leave from work when they have unpleasant symptoms, but some women do not take it, especially in male-dominated environments.

The researchers found that women attending work or school and being less productive due to symptoms may actually be having a bigger impact on productivity than taking time off.

"Menstruation-related symptoms cause a great deal of lost productivity, and presenteeism is a bigger contributor to this than absenteeism. Taking all the symptoms into account, it seems likely that the real impact of [menstruation-related symptoms] is underestimated in the general population. Despite being almost two decades into the 21st century, discussions about [symptoms] may still be rather taboo," they concluded.

The research was published in BMJ Open.