The aim of our study was to evaluate by means of ambulatory 24 h monitoring the diurnal systolic (SBP) and diastolic (DBP) blood pressure profiles in a group (n = 18) of gravid patients with pre-eclampsia compared with a group (n = 17) of healthy control subjects matched for age and week of gestation to assess whether: (i) ambulatory BP is also raised in pre-eclampsia; (ii) the increase of BP, if present, occurs to the same extent during both daytime and night; and (iii) a blunted BP pattern is consistently present in pre-eclampsia. BP was recorded at intervals of 15 min for 25 h using a TM2420 non-invasive pressurometer. The presence of a circadian rhythm of BP was assessed by cosinor analysis. SBP was higher in women with pre-eclampsia (24 h average 115 +/- 11 vs. 136 +/- 12, P = 6 x 10(-6); daytime 117 +/- 12 vs. 139 +/- 13, P = 6 x 10(-6); night 110 +/- 11 vs. 129 +/- 14, P = 5 x 10(-5) as well as DBP (24 h average 67 +/- 5 vs. 86 +/- 6, P = 8 x 10(-12); daytime 69 +/- 6 vs. 89 +/- 5, P = 2 x 10(-11); night 62 +/- 4 vs. 80 +/- 8, P = 5 x 10(-10).(ABSTRACT TRUNCATED AT 250 WORDS)