Stress, IgE sensitization, and lung function may contribute to these associations.<h4>Objective</h4>We investigated the effect of allergy and stress on the association between maternal asthma and adverse outcomes; and examined the association between lung function and adverse perinatal outcomes.<h4>Methods</h4>In the MAESTRO cohort of pregnant women recruited from urban antenatal clinics 2011-16, 1511 singleton pregnancies were followed to delivery (3.5% preterm), and 242 underwent spirometry. Here, IGHE is linked to asthma.