Get a group of women together in a room, and it won’t take long to find out that not everyone’s periods are made equal.
While some of us may experience just light cramping during that time, for a huge proportion of women the pain is disabling enough to seriously affect their work.
A YouGov survey of 1,000 women for BBC Radio 5 live’s Emma Barnett programme found that 52% of women have found period pain severe enough that it has affected their ability to work.
But a large proportion of women - 27% - are afraid to admit it to their bosses.
And of the original 52%, nearly a third had taken at least a day’s sick leave as a result.
Dr Gedis Grudzinskas, a London-based consultant gynaecologist, has said that women should be more open about their period pain, and employers be more understanding.
He told the BBC: “Menstruation is normal, but some women suffer terribly and they suffer in silence.
"I don’t think women should be shy about it, and companies should be accommodating with leave for women who are struggling with painful periods.”
He also suggested that employers introduce “menstrual leave”, which is already offered to female employees in Japan.
“Menstrual leave would make people feel more happy and comfortable in the workplace, which is a positive thing,” he said.
“There is also a lack of awareness about when painful periods mean that something is going wrong, like endometriosis.
"People forget that women make up half the workforce.
"If they feel supported, it will be a happy and productive workforce.”
Do you think employers should introduce “menstrual leave”? Tweet us at @YahooStyleUK.