NEW YORK, April 23 (Reuters) -- Women with asthma who take oral contraceptive pills may have better control of their asthma in the week leading up to their menstrual cycle than women with asthma who are not on the Pill, Scottish researchers report.
Previous studies have shown that up to 40% of women may experience a worsening of asthma symptoms in the week leading up to their period, probably due to changes in certain hormones. This phenomenon is often referred to as premenstrual asthma, or PMA.
The study looked at hormone levels throughout the menstrual cycle in 18 women with asthma. The researchers also assessed the women's reaction to an inhaled substance called adenosine monophosphate (AMP). AMP causes release of inflammatory substances that lead to the airway "twitchiness" seen in asthma. Half the women in the study reported regular use of oral contraceptive pills.
Women taking the Pill did not experience the fluctuation in hormones prior to their period seen in women not taking oral contraceptives, the researchers report this month in the American Journal of Respiratory and Critical Care Medicine, published by the American Lung Association. And women not taking the Pill had significant increases in airway "twitchiness" -- increases not seen in the group on the Pill.
Another finding was that women not on the Pill had significant variability in their lung function in the morning versus the evening, while women taking the Pill had no significant differences, said lead researcher Dr. Brian J. Lipworth, of the University of Dundee.
"It is possible that... female sex-steroid hormones may be used therapeutically in females with unstable asthma or those with premenstrual asthma not controlled by conventional therapy," write the researchers.
In another study, published in the April issue of the journal Chest, Lipworth and colleagues report that high levels of progesterone, but not estrogen cause a worsening of asthma just before menstruation.
However, the results of both studies are in contrast to a two-year-old study showing that women who take estrogen replacement therapy after menopause may be at high risk of developing asthma.
In an editorial published in Chest, Dr. W. Michael Alberts, of the University of South Florida College of Medicine, concludes that although researchers still do not know the precise mechanisms behind premenstrual asthma, it is an important area of research and will aid in the understanding of asthma in general.
SOURCE: American Journal of Respiratory and Critical Care Medicine (1997;155:1273-1277); Chest (1997;111:847-851, 840-842)
