Preeclampsia is recognised as the leading cause of perinatal mortality and morbidity worldwide. Interest has been increasing recently as to the possible impact of sleep disordered breathing (SDB) on the mechanisms of preeclampsia, possibly by augmenting placental hypoxia during sleep. A biomarker of preeclampsia, sFlt-1, has also come to prominence in recent years and is postulated to be a good predictor of preeclampsia as well as a strong indicator of the severity of the disease.The aim of this study was to investigate the effect of CPAP treatment for SDB on sFlt-1 concentrations during pregnancy.Patients were recruited from the outpatients’ clinic in Campbelltown Hospital, Campbelltown, NSW in the first half of 2011. The levels of sFlt-1 in four pregnant women, with or without hypertensive disorders of pregnancy, and with or without SDB were measured using ELISA.Women with SDB and chronic hypertension or preeclampsia had higher levels of sFlt-1 and a greater percentage increase of this marker, and CPAP treatment appeared to attenuate the rise of sFlt-1 as shown in the table below.Initial sFlt1 (pg/ml)Final sFlt1 (pg/ml)% changePatient 1. Chronic HT,SDB19275180169Patient2. Preeclampsia superimposed on chronic HT, SDB87111484670Patient 3. Chronic HT, SDB on CPAP37043116Patient 4. Control5134973Elevated sFlt-1 was associated with untreated SDB in those with chronic hypertension. This study provides feasibility for a larger scale study to occur, to further examine the validity of the hypothesis that CPAP treatment has a beneficial effect on sFLt-1 levels and therefore, may lower the risk and severity of preeclampsia.