Klaus Bonnelykke from the Copenhagen Prospective Studies on Asthma in Childhood at the Danish Pediatric Asthma Center and Zorana Jovanovic Andersen from the Danish Cancer Society based their findings on the use of hormone treatment by 23,138 women who took part in the Danish Diet, Cancer and Health study.
They also denoted asthma hospitalizations and obtained information on participants' smoking status, occupational exposure, body mass index and whether or not they had undergone a hysterectomy to account for other factors relating to asthma incidence.
Women were 1.3-times more likely to be admitted to a hospital for exacerbation of their asthma if they were taking hormone replacement therapy, Bonnelykke said.
The risk increased the longer hormones was used and women taking the drug for longer than 10 years were 1.5-times more likely to require hospital treatment for asthma, the study said.
"Previous research has suggested a link between asthma and female sex hormones, especially HRT. Our findings not only confirm this link, but also extend this to severe asthma exacerbations," Bonnelykke said in a statement.
The findings were presented at the European Respiratory Society's annual Congress in Amsterdam.