Introduction

Sleep-disordered breathing (SDB) is marked by breathing pauses, microarousals, and hemodynamic changes. In the general population, the ailment is associated with multiple adverse cardiac and metabolic outcomes, including high blood pressure, cardiovascular disease, stroke, and altered glucose metabolism. Pregnant women frequently have SDB-related symptoms, which can be triggered by weight gain, airway edema, and hormonal changes. These tend to worsen as the pregnancy progresses. While studies have examined possible links between SDB and adverse pregnancy outcomes, the results have been conflicting. This month, Journal Club members discussed a new study that looked for a relationship between SDB in pregnancy and gestational hypertension/preeclampsia, gestational diabetes, and low birthweight.

Molly J. Stout, MD and George A. Macones, MD, MSCE, Associate Editor

Introduction

Sleep-disordered breathing (SDB) is marked by breathing pauses, microarousals, and hemodynamic changes. In the general population, the ailment is associated with multiple adverse cardiac and metabolic outcomes, including high blood pressure, cardiovascular disease, stroke, and altered glucose metabolism. Pregnant women frequently have SDB-related symptoms, which can be triggered by weight gain, airway edema, and hormonal changes. These tend to worsen as the pregnancy progresses. While studies have examined possible links between SDB and adverse pregnancy outcomes, the results have been conflicting. This month, Journal Club members discussed a new study that looked for a relationship between SDB in pregnancy and gestational hypertension/preeclampsia, gestational diabetes, and low birthweight.

Molly J. Stout, MD and George A. Macones, MD, MSCE, Associate Editor

Study Design

Stout: What was the primary aim of this study?

Epplin: The goal was to determine whether pregnant women with SDB have a higher rate of adverse pregnancy outcomes, such as gestational hypertension/preeclampsia, gestational diabetes, and low-birthweight infants.

Stout: What is the difference between systematic review and metaanalysis?

Wood: A systematic review is a literature review based on a clearly formulated research question. The researchers attempt to identify all relevant work, assess the quality of those studies, and qualitatively summarize the results. In a meta-analysis, on the other hand, statistical methods are used to mathematically combine the results of studies identified in a systematic review. By combining the results of several studies, the power of the analysis is increased. This can be useful for examining rare outcomes. Additionally, by statistically combining the results of similar studies, researchers can assess whether treatment effects are similar or different in diverse clinical scenarios.

Stout: Can you describe the search strategy and inclusion criteria?

Epplin: The authors used 3 main scientific databases for their search. They used search terms related to SDB, such as “snoring” and “sleep apnea,” and combined those with terms related to adverse pregnancy outcomes. Conference abstracts, reviews, or case reports were excluded. Bibliographies of 3 review papers were evaluated for additional citations. To be included, the study had to address their primary question of the association of SDB with adverse pregnancy outcomes, and it had to include a comparison group.

Stout: How did the authors define SDB for these analyses? Why is this important?

Wood: The authors defined SDB according to either a polysomnographic (PSG) diagnosis of obstructive sleep apnea-hypopnea or a probable/presumed diagnosis of obstructive sleep apnea (OSA); the latter was based on clinical symptoms, which included snoring, nocturnal choking/gasping, and witnessed apneas or on simplified sleep recordings that showed evidence of upper airway obstruction (inspiratory flow limitation) and/or repetitive oxygen desaturations. This is important. If the authors only included studies with strict PSG diagnosis, they might have missed essential findings in studies of patients whose diagnoses were based on clinical symptoms—clinical symptom scoring could be the most practical method used in daily medicine. The downside of including clinical diagnosis is that some participants in individual studies might not have truly had OSA.