A new study suggests that a woman's menstrual cycle can affect respiratory symptoms, potentially exacerbating conditions such as asthma.
According to the BBC, Norwegian researchers studied thousands of women with regular menstrual cycles and found that respiratory symptoms became more severe around the time of ovulation.
“The effects of the menstrual cycle on respiratory symptoms in the general population have not been well studied,” said lead author Ferenc Macsali of Norway's Haukeland University Hospital. “In a cohort of nearly 4,000 women, we found large and consistent changes in respiratory symptoms according to menstrual cycle phase, and, in addition, these patterns varied according to body mass index (BMI), asthma, and smoking status.”
Outcome Magazine summarized the findings:
Significant variations over the menstrual cycle were found for each symptom assessed in all subjects and subgroups. Reported wheezing was higher on cycle days 10-22, with a mid-cycle dip near the putative time of ovulation (~days 14-16) in most subgroups.
Shortness of breath was highest on days 7-21, with a dip just prior to mid-cycle in a number of subgroups. The incidence of cough was higher just after putative ovulation for asthmatics, subjects with BMI ≥ 23kg/m2, and smokers, or just prior to ovulation and the onset of menses in subgroups with a low incidence of symptoms.
The BBC notes that "of those studied, 28.5 percent were smokers and 8 percent had been diagnosed with asthma."
The study was published online Nov. 9 in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.
"Our finding that respiratory symptoms vary according to the stage of the menstrual cycle is novel, as is our finding that these patterns vary according to BMI and smoking status," Macsali said in a journal news release, according to HealthDay News. "These relationships indicate a link between respiratory symptoms and hormonal changes through the menstrual cycle."
Macsali added that the results may help women with asthma better manage their symptoms.
"Our results point to the potential for individualizing therapy for respiratory diseases according to individual symptom patterns," he said. "Adjusting asthma medication, for example, according to a woman's menstrual cycle might improve its efficacy and help reduce disability and the costs of care."
Dr. Samantha Walker of charity Asthma UK concurred.
"This research is really interesting, and could help women with asthma to manage their condition better," Walker told the BBC. "Asthma can be triggered by many different things, and this varies from person to person -- but we always encourage people with asthma to be aware of things that trigger their symptoms so that they can take steps to control them.
Though this study may be "novel" in its findings, it would not be the first to find a link between a woman's menstrual cycle and changes in asthma symptoms.
In 1996, the New York Times reported that a study published in the Archives of Internal Medicine had provided evidence to support this connection.
The study, which had looked at the menstrual phase of 182 female patients who needed emergency-room treatment for asthma at hospitals in Pennsylvania, found that "hormonal changes that occur as menstruation starts may make some asthmatic women more vulnerable to attacks." Specifically, researchers found that 20 percent of the patients were preovulatory and 24 percent were in the ovulatory phase when the attacks occurred.
The Times also pointed out that the possibility of such a link had been first reported in a medical journal in 1931, though it was a connection that had "never been proved or studied extensively" before.
According to statistics provided by the Asthma and Allergy Foundation of America, nearly 25 million Americans suffer from asthma and more than 3,300 die from the condition every year. The condition is also said to be more prevalent among adult women than men.