Oral Contraceptives and Asthma Control

Asthma is a chronic inflammatory disorder of the airways affecting approximately 15 million
individuals in the U.S. The rate of asthma exacerbations among women is twice that of men
after adolescence, and a large proportion of females with asthma report worsened asthma
symptoms during different phases of the menstrual cycle. Hormonal influences have been
hypothesized to account for these differences. Decreased peak flow rates and increased
symptoms have been found in females during the premenstrual phase of the menstrual cycle
when estrogen and progesterone levels are low. Estrogen and progesterone have both been
found to reduce smooth muscle contractility and increase bronchial smooth muscle relaxation.
A perimenstrual shift toward a Th2 (allergic) phenotype characterized by a decreased
interferon-gamma to interleukin-10 ratio has been demonstrated in healthy women not using
oral contraceptives compared to midcycle; however, the effect was blunted in healthy oral
contraceptive pill users, implying hormonal modulation of the allergic phenotype. Several
case reports have demonstrated a therapeutic benefit of oral contraceptives in decreasing
asthma exacerbations and corticosteroid requirements. Human studies have demonstrated that
estrogen decreases pro-inflammatory cytokine generation, neutrophil recruitment, and
inhibits inducible nitric oxide synthase activity, which could lead to lower exhaled nitric
oxide levels.

The measurement of the fractional concentration of exhaled nitric oxide (FENO) is a
non-invasive method to assess airway inflammation in adults and children with asthma. The
hypotheses of the current study are that women using oral contraceptives will have lower
FENO levels and better asthma control as assessed by the Asthma Control TestTM during
different phases of the menstrual cycle. This study may identify clinically important
changes in FENO levels and asthma control during the menstrual cycle and modification of
these effects by oral contraceptive pills. This data may lead to future studies aimed at
identifying therapeutic roles for hormones in asthma therapy in women.