Study objectives: Preeclampsia affects 5% to 7% of pregnancies, is strongly associated with low birth weight and fetal death, and is accompanied by sleep disordered breathing. We hypothesized that sleep disordered breathing may link preeclampsia with reduced fetal movements (a marker of fetal health), and that treatment of sleep disordered breathing might improve fetal activity during sleep.
Design, setting, and participants: First, a method of fetal movement recording was validated against ultrasound in 20 normal third trimester pregnancies. Second, fetal movement was measured overnight with concurrent polysomnography in 20 patients with preeclampsia and 20 control subjects during third trimester. Third, simultaneous polysomnography and fetal monitoring was done in 10 additional patients with preeclampsia during a control night and during a night of nasal CPAP.
Intervention: Overnight continuous positive airway pressure.
Measurements and results: Women with preeclampsia had inspiratory flow limitation and an increased number of oxygen desaturations during sleep (P = 0.008), particularly during REM sleep. Preeclampsia was associated with reduced total fetal movements overnight (319 [SD 32]) versus controls (689 [SD 160], P < 0.0001) and a change in fetal movement patterns. The number of fetal hiccups was also substantially reduced in preeclampsia subjects (P < 0.0001). Continuous positive airway pressure treatment increased the number of fetal movements and hiccups (P < 0.0001 and P = 0.0002, respectively).
Conclusions: The effectiveness of continuous positive airway pressure in improving fetal movements suggests a pathogenetic role for sleep disordered breathing in the reduced fetal activity and possibly in the poorer fetal outcomes associated with preeclampsia.