Menstrual symptoms may be having a big impact on women's productivity in work, a new study suggests.

According to the findings, symptoms may be linked to almost nine days of lost productivity annually through presenteeism, which is working when feeling unwell.

Menstrual symptoms can include abdominal cramps, muscle and joint pain, tender breasts, headache, bloating and fatigue.

Dutch researchers set out to assess lost productivity associated with menstrual symptoms in almost 33,000 women between the ages of 15 and 45. Levels of absenteeism and presenteeism in work and school were measured, as were details about their menstrual cycles.

The study found that blood loss lasted an average of five days and 31% of women had visited their family doctor due to menstrual symptoms. A further 14% had seen a gynaecologist.

Overall, 14% said they had taken time off work or school as a result of their symptoms, although the average amount of sickness leave was just over one day per year.

However, presenteeism seemed to be a much bigger issue, with 81% stating that they had continued to work/study while feeling unwell, and that they were less productive as a result of their symptoms.

Overall, productivity was less than expected on 23 work/study days out of the year, while lost productivity amounted to almost nine days per year.

The researchers calculated that women were, on average, less productive for 33% of the time as a result of menstrual symptoms.

They pointed out that when women called in sick because of their menstrual symptoms, just 20% told their employer/school the real reason for their absence.

Meanwhile, almost 68% said they wished they had the option of more flexible hours around the time of their period.

"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 is underestimated in the general population," the researchers said.

They highlighted that menstrual symptoms are still not openly talked about by many people.

"Despite being almost two decades into the 21st century, discussions about symptoms may still be rather taboo," they added.

Details of these findings are published in the journal, BMJ Open.