Evidence of placental hypoxia in maternal sleep disordered breathing

Sleep disordered breathing (SDB) represents a spectrum of disorders, including habitual snoring and obstructivesleep apnea (OSA). Sleep disordered breathing is characterized by chronic intermittent hypoxia, airflowlimitation, and recurrent arousals, which may lead to tissue hypoperfusion, hypoxia, and inflammation. In thisstudy, we aimed to examine whether SDB during pregnancy was associated with histopathologic evidenceof chronic placental hypoxia and/or uteroplacental underperfusion. The placentas of women with OSA (n = 23) and habitual snoring (n = 78) as well as nonsnorer controls (n = 47) were assessed for histopathologic andimmunohistochemical markers of chronic hypoxia and uteroplacental underperfusion. Fetal normoblastemia wassignificantly more prevalent in SDB placentas than in those of nonsnorer controls (34.6% and 56.5% in snorersand OSA, respectively, versus 6.4% in controls). Expression of the tissue hypoxia marker carbonicanhydrase IX (CAIX) was more common in OSA placentas than controls (81.5% and 91.3% in snorersand OSA, respectively, versus 57.5% in controls). Adjusting for confounders such as body mass index, diabetes mellitus, or chronic hypertension did not alter the results. The uteroplacental underperfusion scores weresimilar among the 3 groups. Our findings suggest that SDB during pregnancy is associated with fetoplacentalhypoxia, as manifested by fetal normoblastemia and increased placental carbonic anhydrase IX immunoreactivity. The clinical implications and underlying mechanisms remain to be determined.