The research has been compiled by staff at Imperial College Healthcare.
More than 260,000 women were surveyed across its sites which include Hammersmith Hospital and Queen Charlotte’s and Chelsea.
The research has been published in ERJ Open Research.
It shows an increase in asthma attacks in women with asthma who are taking the progesterone-only pill.
They are also aged under 35, or using fewer asthma treatments, or with a type of asthma called eosinophilic asthma.
There was no increase in asthma attacks for women taking the combined oestrogen and progesterone contraceptive pill.
The findings could be an important step towards understanding why women are more likely to have severe asthma than men.
