Objective: Definition of arterial hypertension and management decision making in guidelines is still based on office blood pressure measurement (OBPM), both in general and pregnant population, although in clinical practice 24h ambulatory monitoring (ABPM) seems to be more accurate, which if not available often replaced with home BP (HBPM). Information on differences between values of BP depending on method in course of pregnancy are scarce. Aim of the study was to assess profile and compare results of three methods of BP measurement used simultaneously – HBPM, OBPM and 24 ABPM in pregnancy in real clinical setting with regard to hypertensive status, development of preeclampsia (PE) and time of pregnancy. Design and method: In a prospective longitudinal study 241 pregnant women admitted between 2017 and 2023 to outpatient clinic had their BP examined - monthly throughout pregnancy and 6-8 weeks, 6 months and 1 year postpartum. On each occasion data on HBPM (from 7 days prior) were collected, compared with OBPM in standardized conditions (OMRON®-705I) as well as with result of 24h ABPM (AND®TM-2430). Pharmacotherapy in hypertensive patients was managed in accordance with ESH/ESC guidelines. Results: We have recruited 40 normotensive controls and 201 women with hypertension (145 chronic; 56 pregnancy induced). Preeclampsia developed in 49 of hypertensives (HT+PE) (18,6% of chronic HT, 39,3% of PIH) – on average in 32,8 w.g. (20-39). SBP/DBP as median are presented in table 1. BP of controls differed significantly from both complicated (HT+PE) and uncomplicated hypertensive patients (HT) in all three methods at all stages of pregnancy and postpartum (p< 0.05). Significant differences between HT+PE and HT are marked in table 2 in gray. Conclusions: Regardless of method of BP assessment and good BP control with antihypertensives achieved values in HT pregnancies differed significantly from normotensive pregnancies. Preeclamptic patients were characterized with significantly higher BP values in HBPM, OBPM and – most strongly expressed - in night-ABPM than uncomplicated hypertensives already 2 months before average time of PE recognition. The night-time BP values from ABPM seems to have the strongest predictive and diagnostic value for early recognition of preeclampsia.