The relationship between hypertension during pregnancy and sleep-disordered breathing may be partly mediated by obesity, new research suggests.
An article published in the Journal of Sleep Research details the results of a case-control study in 80 pregnant women – 40 normotensive and 40 with either gestational hypertension or preeclampsia – who were matched on body mass index.
Nearly half of the women in the study (45%) met the criteria for sleep-disordered breathing – defined as a respiratory disturbance index of 5 or above. The incidence was higher among women with hypertension (53%) than among women in the normotensive control group (38%), but the difference was not statistically significant.
There were also no significant differences in median respiratory disturbance index or apnea-hypopnea index between the hypertension and control groups.
However, the incidence of more severe sleep-disordered breathing – a respiratory disturbance index of at least 10 – was significantly greater in the hypertensive group (35% vs. 14%; P = .04). The women with pregnancy-related hypertension also had significantly higher respiratory disturbance index during non–rapid eye movement sleep and when they were sleeping on their back.
The severity of hypertensive disease did not affect the prevalence of sleep-disordered breathing.
Danielle L. Wilson of the Institute for Breathing and Sleep at Austin Health in Melbourne and her coauthors wrote that, while previous research has pointed to a link between hypertension in pregnancy and sleep-disordered breathing, this is the first study to explore the potential confounding role of obesity.