Effects of Gestational Intermittent Hypoxia on the Respiratory System: A Tale of the Placenta, Fetus and Developing Offspring

Obstructive sleep apnea (OSA) is a common sleep disorder that is associated with a wide variety of health conditions, including cardiovascular, cerebrovascular, metabolic, neoplastic, and neurocognitive manifestations. OSA is mainly characterized by repeated upper airway obstructions during sleep that cause episodes of chronic intermittent hypoxia (IH), resulting in tissue hypoxia-reoxygenation. Decreased arterial oxygen pressure (PaO2) and hemoglobin saturation (SatO2) stimulate reflex responses to overcome the obstruction. The prevalence of OSA is significant worldwide, particularly in women during pregnancy, due to the physiological changes associated with this stage of life, especially in its later stages. It is associated with an increased risk of hypertension, pre-eclampsia and diabetes, among others. OSA during pregnancy can interfere with normal fetal development and is associated with growth retardation, preterm birth, or low term weight. Carotid body stimulation and hypoxia-reoxygenation episodes contribute to cardiovascular disease and oxidative stress, that can harm both, mother and the fetus, even into the adulthood. Because gestational intermittent hypoxia (GIH) is the hallmark of OSA in pregnancy, this review examines the impact of GIH on maternal, fetal, and offspring respiratory outcomes. Most adverse outcomes can be prevented by continuous positive airway pressure (CPAP) therapy and lifestyle changes if gestational OSA is detected early and treated appropriately.