The prevalence and clinical significance of nocturnal hypertension in pregnancy

Objective To determine (a) the prevalence of hypertension during sleep in p re-eclampsia and gestational hypertension, and (b) whether women with hyper tension during sleep have worse pregnancy outcomes than hypertensive pregna nt women with controlled (normal) blood pressure (BP) during sleep. Design Prospective double-blind cohort study. Setting Inpatients and outpatients managed in a day assessment unit (DAU) a t St George Hospital, Sydney, Australia. Participants A total of 186 hypertensive pregnant women, 158 of whom had su ccessful 24 h BP monitoring; 40% had proteinuric pre-eclampsia (PE), 43% ge stational hypertension (GH) and 17% essential hypertension (EH). Interventions Blood pressure, 24 h non-invasive, monitoring (Spacelabs 9020 7) was undertaken successfully in 158 women with PE, GH or EH, whether or n ot they were receiving antihypertensives. Women and clinicians were blinded to results of these BP monitors. Sleep hypertension was defined as BP > 11 7/68 mmHg at 26-30 weeks or > 123/72 mmHg after 30 weeks gestation. Main outcome measures Maternal and fetal outcomes were compared between wom en with and without sleep hypertension and the prevalence of sleep hyperten sion was determined. Results Sleep hypertension was present in 59%, more commonly in PE (79%) th an GH/EH (45%), P < 0.0001. Sleep hypertensives also had higher routine sph ygmomanometer Bps [137(10)/91(7) mmHg; mean(SD)] than women with normal sle ep BP [130(12)/87(8) mmHg] P = 0.007, and higher awake ambulatory blood pre ssure monitoring (ABPM) Bps [137(8)/88(7) versus 127(7)/79(6) mmHg], P < 0. 0001. Awake, but not sleep, average heart rate was lower in sleep hypertens ives [85(11) versus 91(10) beats per minute, bpm], P = 0.002. Sleep hyperte nsives had a significantly greater frequency of renal insufficiency, liver dysfunction, thrombocytopenia and episodes of (awake) severe hypertension ( P < 0.05), as well as lower birth weight babies [2715(808) versus 3224(598) g, P < 0.0001]. Conclusions Hypertension during sleep is a common finding in women with hyp ertensive disorders of pregnancy, particularly pre-eclampsia. These women a lso have higher awake BPs and a greater frequency of adverse maternal and f etal outcomes. These findings are largely explained by the greater likeliho od of pre-eclamptics having sleep hypertension.