Nov. 6, 2009 -- Treatment with oral contraceptives may benefit premenopausal women with asthma, even if their asthma symptoms are not strongly linked to their monthly menstrual cycles, early research suggests.
In a small but rigorously designed study, researchers from the University of Alberta confirmed that fluctuating levels of the sex hormones estrogen and progesterone have a direct impact on markers of airway inflammation.
The study included 17 premenopausal women with moderate to severe asthma who met with the research team daily over the course of a complete menstrual cycle (around 36 days).
Estrogen and progesterone levels were measured at each visit. Asthma symptoms and markers of airway inflammation were also monitored daily, and allergyskin-prick tests were conducted every other day.
"This study took a lot of dedication on the part of everyone involved," Mandhane says. "We endured snow storms, power outages, and university closures. When people were going away for weekend trips I would be at their house at 5 a.m. or an assistant would be there."
This dedication meant that almost 99% of the planned daily assessments were actually carried out.
Nine of the women in the study were using oral contraceptives and eight were not. Four of the 17 had menstrual-cycle associated asthma symptoms.
"Since women taking oral contraceptives don't have significant changes in estrogen and progestin through their menstrual cycles, we did not expect to see changes in markers of asthma through the cycle," Mandhane says. "Women who are not on oral contraceptives should have changes in estrogen and progesterone and as a result they should have changes in these markers. That is what we found."
He says women who experience big fluctuations in progesterone but few changes in estrogen during their cycle are probably most vulnerable to cycle-related asthma.
The study was published this week in the November issue of the journal Chest.
Mandhane believes the findings justify larger studies examining oral contraceptives as a treatment for asthma in premenopausal women.