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Poor asthma control during pregnancy trims live birth rate



Women with poorly-controlled asthma during pregnancy had a substantially decreased rate of live births, and among the live births had a significantly increased rate of both preterm delivery and neonatal intensive care admissions, according to a review of insurance claims data for more than 1 million American women during 2011-2015.

Jennifer Yland, Harvard School of Public Health, Boston Mitchel L. Zoler/MDedge News

Jennifer Yland

On the other hand, asthma severity, which the researchers inferred based on the type and amount of treatment patients received, showed essentially no link with the live birth rate, Jennifer Yland said at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.

“The findings add to the body of evidence that relate poor asthma control to an increased risk for pregnancy complications.” explained Michael X. Schatz, MD, an allergist at Kaiser Permanente of Southern California, in San Diego, and a coauthor of the study.

Results from several prior studies had shown links between asthma and an increased rate of preterm birth, “but the larger, more generalizable population is a strength of the current findings. Results from prior studies have less frequently shown a link between asthma during pregnancy and neonatal ICU admissions,” he added.“The findings strengthen the case for good asthma control during pregnancy.”

For their review, Ms. Yland and her coauthors used insurance claims data from privately-insured American women aged 12-55 years who were pregnant and had drug prescription records during the study period. The database included 996,861 women without an asthma diagnosis and 29,882 women diagnosed with asthma. The analysis excluded women diagnosed with chronic obstructive pulmonary disease at least twice during pregnancy.

To analyze the pregnancy outcomes by asthma severity Ms. Yland and her associates divided the asthma patients into five subgroups based on the drug regimens they were on during pregnancy as a surrogate marker of disease severity. This analysis showed no relationship between disease severity and live birth rate.

The researchers also ran an analysis that divided patients into the quality of their management during pregnancy – either good or poor – based on either of two markers of poor control: filling five or more prescriptions for a short-acting beta-antagonist, or at least one exacerbation episode defined as an asthma-related emergency department visit, hospitalization, or need for oral corticosteroid treatment. By these criteria 7,135 (24%) of the pregnant women with asthma were poorly controlled. The live birth rate was 74% among women without asthma, 71% among those with well-controlled asthma, and 68% among women with poorly-controlled asthma, reported Ms. Yland, a researcher at the Harvard T.H. Chan School of Public Health in Boston.

In a multivariate analysis that adjusted for demographic differences and comorbidities, women with poorly-controlled asthma had preterm delivery a statistically significant 30% more often than did women with well-controlled asthma, and the rate of neonatal ICU admissions was a significant 24% higher in women with poorly-controlled asthma, compared with women who had well-controlled asthma. However, the rates of small-for-gestational-age infants and infants with congenital malformations was not significantly different between the well-controlled and poorly-controlled subgroups.

The finding that almost a quarter of the pregnant women in the study were poorly controlled wasn’t surprising, Dr. Schatz said in an interview. In some studies as many as half the asthma patients have poor control.

The 24% rate of poor asthma control during pregnancy in the studied women is “most likely an underestimate of poor control in the general population” because the study used data from women with commercial health insurance, noted Sonia Hernandez-Diaz, MD, lead investigator for the study and professor of epidemiology at Harvard T.H. Chan School of Public Health. “More disadvantaged populations, such as pregnant women on Medicaid, tend to have worse control.”

Barriers to good asthma control during pregnancy include smoking, weight gain, undertreatment, poor adherence, and viral infection. The overall approach to managing asthma during pregnancy is the same as when women are not pregnant, although certain asthma medications have a better safety record during pregnancy. “The most reassuring data exist for albuterol and inhaled steroids, particularly budesonide and fluticasone. Reassuring data also exist for the long-acting beta agonists salmeterol and formoterol, which are combined with inhaled steroids, and for montelukast,” Dr. Schatz said.

This is the first study to assess the impact of asthma management on pregnancy outcome in such a large population. The large number of women included provided a lot of statistical power and allowed the analyses to control for several potential confounders, Ms. Yland noted in an interview. She plans to expand the analysis with Medicaid data to try to further increase the generalizability and precision of the findings.

The study was funded by GlaxoSmithKline, and a coauthor of the study is a company employee. Ms. Yland had no disclosures. Dr. Schatz has received research funding from ALK, AstraZeneca, Medimmune, GlaxoSmithKline, and Merck. Dr. Hernandez-Diaz has been a consultant to Boehringer Ingelheim, Roche, and UCB, and has received research funding from GlaxoSmithKline, Lilly, and Pfizer.

SOURCE: Yland J et al. J Allergy Clin Immunol. 2019 Feb;143[2]:AB422.

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