- PMS, or premenstrual syndrome, is the name for the symptoms some women experience before their period which can include mood swings, feeling anxious or irritable and tiredness.
- Headaches or cramps ahead of or during menstruation are also common.
- But each person's symptoms are different and can vary from month to month.
A football app start-up in Gothenburg is set to become the first business in Sweden to be certified as menstruation-friendly. But how much do employees really want to talk about their periods?
Rows of top-division European football kits hang from a giant goal net hooked to the ceiling, while two male developers kick a ball around on a green fake grass carpet.
This isn't the most obvious place to be championing a more supportive environment for women during their periods.
Indeed, Forza Football's chief executive Patrik Arnesson admits he "didn't think about the menstrual cycle at all" before a female employee asked if the firm could take part in a pilot scheme designed to break down taboos around menstruation.
"No one had actually told me they had to leave work to go home because of PMS," he says. "And then I actually realised that this is a problem and I haven't even reflected on it."
PMS, or premenstrual syndrome, is the name for the symptoms some women experience before their period which can include mood swings, feeling anxious or irritable and tiredness.
Headaches or cramps ahead of or during menstruation are also common. But each person's symptoms are different and can vary from month to month.
The project in Gothenburg is being led by a non-profit called Mensen (Menses) which was given a grant of 530,000 kronor ($58,400; £44,900) from the Swedish government's Gender Equality Agency at the end of last year.
'SOMETHING WE HAVE TO TALK ABOUT'
Since March it has started inviting all employees to attend discussions and workshops about the effects of menstruation.
These will then be used to form the basis for a certification programme that the organisation wants to see rolled out nationwide or even globally.
Klara Rydström, who is leading the project for Mensen, says that while Sweden has a global reputation for supporting women's rights, there is still a stigma around discussing menstruation in many workplaces.
"But it's something we have to talk about, because it's a bodily function - a normal bodily function - just as being thirsty and you have to have water, or you're hungry and you have to have a lunch break," she argues.
Forza Football, which currently has around 60 workers and a 70:30 ratio of male and female employees, has already made several key changes - including providing free sanitary products and bins in company toilets
And flexible working has been introduced for all staff, so they can pick their own office hours or work from home when they want to.
Women are actively encouraged to tell other team members if they choose to be away from the office because of PMS and even to share their cycle dates and symptoms with other team members in advance if they feel comfortable with the idea.
"I get really sad and lose all my self-confidence and self-esteem. It's kind of hard to do meetings where I need to be focused and positive," says software developer and project manager Lisa Hammarström.
She says she's felt more relaxed talking about her symptoms since Forza Football started taking part in the Mensen project.
Colleagues are happy for her to have a lighter workload when she's premenstrual, she says, because she's very productive during the rest of the month.
"I realised that it makes things easier for me if people know what is going on and how it affects your work."
What do men think?