Scientists have made a discovery that could explain why one third of women experience heavy periods – where they lose more than 80 millilitres of blood – at least once in their lives.
Jackie Maybin, from the MRC Centre for Reproductive Health at the University of Edinburgh said: “Heavy menstrual bleeding is one of the most common reasons for referral to a gynaecologist. It can have a big impact on a person’s quality of life.”
While physical causes such as fibroids and endometriosis can often be identified as the cause of excessive menstrual bleeding, around half the time why women experience heavy periods has remained a mystery.
When there is no physical explanation, doctors often prescribe hormonal medications like the pill, anti-inflammatories or treatments that encourage clotting such as tranexamic acide. Many women find these treatments aren’t effective or give them serious side effects.
Maybin and her team believe that low levels of protein called HIF1 might be the cause. It activates other genes when levels of oxygen drop, which is known to happen in the uterus during a period – and plays a role in repairing the gut.
They scooped out small samples of cells from the uteruses of eight women over a month – four of whom experienced heavy periods. Upon examining the samples, they found that HIF1 is present in the uterus during a woman’s period, but those who experienced heavy bleeding had much lower levels of the protein.
They did some further investigating using two groups of mice – one that was normal and another that had been genetically modified so that they are unable to produce the protein, and then they were induced to get their periods once a month to mirror the human menstrual cycle.
The researchers found that 16 hours after bleeding had stopped, the normal mice’s uteruses were showing signs of repair. But the mice that didn’t have the HIF1 protein showed no signs of recovery, even after 24 hours.
Because the study was so small, the results need to be replicated in a much larger group to conclusively determine that missing HIF1 is linked to heavy bleeding, and the researchers are now working on this.