Asthma control as fetal protection in pregnancy, with Rachel Meislin, MD

Uncontrolled asthma, rather than the diagnosis itself or the medications used to treat it, is the primary driver of adverse pregnancy outcomes, according to Rachel Meislin, MD, board-certified OB-GYN and maternal-fetal medicine specialist at the Icahn School of Medicine at Mount Sinai, who discussed a review she co-authored in the American Journal of Obstetrics and Gynecology.¹

Asthma affects 8% to 13% of pregnancies, per the review, which found that uncontrolled disease is associated with higher rates of preterm birth (adjusted odds ratio: 1.3 vs 1.6), hypertensive disorders of pregnancy (adjusted odds ratio: 1.2 vs 1.5), and impaired fetal growth or small-for-gestational-age neonates (adjusted odds ratio: 1.2 vs 1.4) compared with controlled disease.

Meislin said the distinction between diagnosis and control is understood but inconsistently applied.

“Many patients, and often some clinicians, continue to think of asthma medications as the exposure we should be avoiding and be concerned about. But in reality, the greater risk is really uncontrolled or undertreated disease,” she said.

She framed disease control as aligned with, not opposed to, fetal safety.

“It's really about having control as a fetal protective strategy, and that's the conversation that we'll have with the patient, not really competing with fetal safety; it's actually our shared goal,” Meislin said.

“Pregnancy itself is really a dynamic immunologic state, not just Th2 predominant, but we do know that there are changes that can kind of favor that pathway,” she added. “Some patients will improve, some will get worse, and some remain stable, but we don't have a prediction model yet for how that will happen.”

Given that uncertainty, Meislin recommended that clinicians expect worsening symptoms in pregnancy.

“We should really assume that patients will probably get worse,” she said, adding, “This means that at the initial prenatal visit, it's important to establish a baseline early. This may be especially important in the second and third trimester, as pregnancy physiology leads to changes in respiratory adaptation and sleep-disordered breathing at times, and can lead to a loss of control.”

Per the review, guidance aligned with international asthma guidelines emphasizes proactive monitoring, routine assessment of symptoms and objective measures, and continuation or escalation of controller therapy to maintain control, with a goal of complete symptom remission.

Reference:

Meislin R, Bose S, et al. Asthma in pregnancy: contemporary management. Am J Obstet Gynecol. 2026. Accessed August 19, 2026. https://www.ajog.org/article/S0002-9378(26)00153-5/abstract