During pregnancy several physical and hormonal alterations may affect normal sleep and the respiratory system and predispose pregnant women to the development of sleep-disordered breathing (SDB) or worsen pre-existing obstructive sleep apnea syndrome (OSAS). SDB has been associated with several complications of pregnancy affecting maternal and fetal health. Clinicians should evaluate more closely obese pregnant women and those who develop hypertension. Early recognition and treatment of SDB may improve the outcome of pregnancy but the indications for treatment of OSAS need to be investigated. The diagnosis of OSAS in pregnancy requires a high index of suspicion and prevention of suspected SDB should be incorporated in the management of pregnancy.