Adverse pregnancy outcomes and pharyngeal flow limitation during sleep: Nulliparous Pregnancy Outcomes Study Monitoring Mothers-to-be (nuMoM2b)

Background Pharyngeal flow limitation during pregnancy may be a risk factor for adverse pregnancy outcomes but was previously challenging to quantify. Our objective was to determine whether a novel objective measure of flow limitation identifies an increased risk of pre-eclampsia (primary outcome) and other adverse outcomes in a prospective cohort: Nulliparous Pregnancy Outcomes Study Monitoring Mothers-to-be (nuMoM2b). Methods Flow limitation severity scores (0%=fully obstructed, 100%=open airway), quantified from breath- by-breath airflow shape, were obtained from home sleep tests during early (6-15 - 15 weeks) and mid (22-31 - 31 weeks) pregnancy. Multivariable logistic regression quantified associations between flow limitation (median overnight severity, both time-points averaged) and pre-eclampsia, adjusting for maternal age, body mass index (BMI), race, ethnicity, chronic hypertension and flow limitation during wakefulness. Secondary outcomes were hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM) and infant birthweight. Results Of 1939 participants with flow limitation data at both time-points (mean +/- SD SD age 27.0 +/- 5.4 years and BMI 27.7 +/- 6.1 kg m-2), - 2 ), 5.8% developed pre-eclampsia, 12.7% developed HDP and 4.5% developed GDM. Greater flow limitation was associated with increased pre-eclampsia risk: adjusted OR 2.49 (95% CI 1.69-3.69) - 3.69) per 2 SD increase in severity. Findings persisted in women without sleep apnoea (apnoea- - hypopnoea index <5 events h-1). - 1 ). Flow limitation was associated with HDP (OR 1.77 (95% CI 1.33-2.38)) - 2.38)) and reduced infant birthweight (83.7 (95% CI 31.8-135.6) - 135.6) g), but not GDM. Conclusions Greater flow limitation is associated with increased risk of pre-eclampsia, HDP and lower infant birthweight. Flow limitation may provide an early target for mitigating the consequences of sleep disordered breathing during pregnancy.