The effect of pregnancy on asthma varies; deterioration is slightly more common than improvement, but most pregnant women do not have severe attacks.
The effect of asthma on pregnancy also varies, but severe, poorly controlled asthma increases risk of (1)
Maternal morbidity and mortality
Also, cesarean delivery is required more often in patients with asthma.
General reference
1. Abdullah K, Zhu J, Gershon A, Dell S, To T: Effect of asthma exacerbation during pregnancy in women with asthma: a population-based cohort study. Eur Respir J 55(2):1901335, 2020. doi:10.1183/13993003.01335-2019
Treatment of Asthma in Pregnancy
Inhaled bronchodilators and corticosteroids
Pregnancy does not usually change treatment of asthma (1). Women are taught strategies to help manage asthma, including how to minimize exposure to triggers and how to serially measure pulmonary function (usually with a handheld peak flow meter).
2).
Treatment references
1. Bonham CA, Patterson KC, Strek ME: Asthma outcomes and management during pregnancy. Chest 153(2):515-527, 2018. doi:10.1016/j.chest.2017.08.029
2. Källén B, Rydhstroem H, Aberg A: Congenital malformations after the use of inhaled budesonide in early pregnancy. Obstet Gynecol 93(3):392-395, 1999.