medwireNews: Researchers say that treatment of sleep-disordered breathing (SDB) with continuous positive airway pressure (CPAP) therapy may improve fetal wellbeing in pregnant women with pre-eclampsia.
They found that fetal movements increased from an average of 319 during a night without CPAP therapy to an average of 592 during the subsequent night with CPAP therapy. Without CPAP therapy, fetal movements decreased steadily during the night by 7.4 movements per hour, whereas with CPAP, the number increased by 12.6 per hour.
"What would otherwise have been considered clinically unimportant or minor 'snoring' likely has major effects on the blood supply to the fetus, and that fetus in turn protects itself by reducing movements," said Colin Sullivan, from the University of Sydney in Australia, in a press statement.
Sullivan and team suggest that SDB affects the fetus by triggering a worsening of the already high peripheral vascular resistance and a decrease in cardiac output in women with pre-eclampsia.
The researchers initially validated a fetal activity monitor against ultrasound in 20 healthy women in the third trimester of pregnancy. This monitor was then used to show that fetal activity was significantly lower in 20 women with pre-eclampsia than in 20 women without the condition, with an average of 289 versus 689 overnight fetal movements.
Women with pre-eclampsia also had marked inspiratory airflow limitation during sleep, with a mean 68% of breaths spent in flow limitation compared with 19% for women without pre-eclampsia. This resulted in a higher number of oxygen desaturations per hour (average five vs three) and a raised apnea-hypopnea index (AHI) score (8.9 vs 5.0 episodes/hour).
The benefits of CPAP therapy were measured in 10 women with moderate-to-severe pre-eclampsia and mild SDB, with an average AHI of 7.0 episodes per hour. A minimal mean CPAP pressure of 7 cm H2O was needed to eliminate upper airway obstruction and airflow limitation.
"The effectiveness of CPAP in restoring fetal activity suggests a pathogenic role for SDB in the reduced fetal activity associated with preeclampsia," say the researchers.
"It is plausible that nasal CPAP treatment of patients with preeclampsia also affected by SDB may potentially provide sufficient improvement in fetal well-being to allow for clinically relevant extensions of pregnancy," they add. "However, this has not yet been studied."