Characteristics unique to females with obstructive sleep apnoea (OSA) or OSA/hypopnoea syndrome (OSAHS) in their clinical presentation, pathophysiology, comorbidities and treatment response compared to males with OSA/OSAHS
| Pathophysiology of OSA/OSAHS | Upper airway less collapsible |
| Shorter airway length, which increases with age | |
| Lower critical closing pressure | |
| Subcutaneous and peripheral fat distribution | |
| Prolonged partial upper airway obstruction leading to increased respiratory resistance, increased end-tidal CO2 | |
| Lower chemoresponsiveness | |
| Lower metabolic rate | |
| Less respiratory drive instability | |
| Progesterone stimulates ventilation | |
| Higher CO2 sensitivity and lower upper airway resistance during the luteal phase of menstrual cycle (high progesterone levels) | |
| Premenopausal females have lower apnoeic thresholds | |
| In pregnancy | Reduction in airway size, fluid retention, weight gain, nasal obstruction |
| Reduced functional respiratory capacity and residual volume | |
| Increased minute ventilation | |
| High progesterone leading to increased upper airway dilator muscle activity | |
| Enhanced chemoreceptor responsiveness | |
| Right-shifted oxygen dissociation curve | |
| Increased maternal heart rate and stroke volume | |
| Less time in the supine position | |
| Clinical presentation | |
| Overall | More likely to present with insomnia, mood disturbances, nightmares, fatigue, lack of energy |
| Greater impairment of quality of life | |
| Higher healthcare expenditure | |
| Higher rate of sick leave, impaired work performance, divorce | |
| Hypothyroidism more common | |
| Less intense snoring | |
| Pregnancy | Increased snoring as pregnancy progresses |
| Snoring/OSA associated with pregnancy-induced hypertension, intra-uterine growth retardation, hypertension and diabetes mellitus | |
| Menopause | Clinical presentation attributed to menopause |
| Doubling of OSA/OSAHS prevalence in menopause | |
| Findings on sleep studies (polysomnography/polygraphy) | Lower AHI overall |
| Shorter apnoeic episodes | |
| More frequent subcriterion events | |
| Lower proportion of supine OSA | |
| Higher frequency of REM-related OSA | |
| Longest apnoeas associated with more severe arterial oxygen desaturation | |
| Increased sleep fragmentation in pregnancy | |
| Comorbidities | More systemic inflammation for given AHI |
| More peripheral and subcutaneous fat distribution premenopausally | |
| Pharyngeal collapsibility in females awaiting bariatric surgery correlates with degree of insulin resistance | |
| Responses to treatment | CPAP trial should be symptom-driven (AHI lower for given clinical symptoms) |
| Lower CPAP pressures more common | |
| MRS use may be higher in mild OSA/OSAHS | |
| Greater voluntary weight loss sustained, but smaller relative drop in AHI |
CO2: carbon dioxide; AHI: apnoea–hypopnoea index; REM: rapid eye movement; MRS: mandibular repositioning splints.