Introduction <p>Women are underdiagnosed with obstructive sleep apnea (OSA) due to differences in anatomy, clinical presentation, and sociocultural factors. The diagnostic criteria for hypopneas, a key component of the apnea–hypopnea index (AHI), plays a critical role in identifying OSA. This review examines the impact of the 4% oxygen desaturation criteria versus the 3% oxygen desaturation criteria, which also includes hypopneas associated with cortical arousals, on OSA diagnosis in women.</p> Methods <p>A scoping review was conducted following PRISMA guidelines. Relevant articles were identified through searches of PubMed/MEDLINE and Google Scholar using terms related to hypopnea scoring criteria, sex differences, and OSA diagnosis. Articles were included if they explored discrepancies between the 4% and 3% criteria with a focus on sex-specific outcomes.</p> Results <p>Eight studies compared the 4% and 3% criteria, highlighting the diagnostic disparity for women. The adoption of the 3% threshold increased OSA diagnosis rates in women by 12.8% to 63% and enhanced detection of moderate-severe OSA. Conversely, reliance on the 4% criterion was associated with lower prevalence estimates of OSA compared to the 3% criterion.</p> Conclusions <p>The use of the 3% hypopnea scoring criteria significantly increases the diagnostic yield of OSA in women. Limited data suggests that treatment of mild OSA in women is beneficial, but more research is needed to explore the long-term impact of more inclusive diagnostic standards on health outcomes.</p>