Chapter 16: Asthma in pregnancy

The course of asthma during pregnancy may be affected by maternal physiological changes and triggers of asthma such as viral infections, exposure to allergens, and nonadherence with therapy. If asthma is uncontrolled, there are recognized harmful effects not only to the mother but also to the fetus. However, with effective asthma control, most women have outcomes, at or near that of the general population. Many medications are considered appropriate for use in pregnancy including inhaled corticosteroids (ICSs) such as budesonide, beclomethasone dipropionate, and fluticasone and the leukotriene receptor antagonists montelukast and zafirlukast. When ICSs or ICS/long-acting beta(2)-adrenergic agonist combinations are not effective during exacerbations of asthma, short courses of oral corticosteroids should be administered earlier rather than later. Spirometry and flow volume loop tracings are useful measures of pulmonary function for gravidas. Results may be compared with nonpregnant reference values. Vocal cord dysfunction may be suspected when the inspiratory loop is truncated. The gravida does not reject the fetus because of lack of vascular continuity, a trophoblast layer causing separation, and suppressive mechanisms at the placental interface. The secretion of IL-10 increases in pregnancy and is lower in women with recurrent spontaneous abortions. Only immunoglobulin G (IgG) subclasses are transported across the placenta, especially IgG1, IgG3, and IgG4. Fetal B cells can produce endogenous IgE by 20 weeks of gestation.