[Nocturnal fall of blood pressure in the first half of pregnancy]

Arterial blood pressure (BP) shows circadian variation. The most important feature of the circadian variation of BP is it fall during sleep. Nocturnal fall of BP achieves at least 10% ("dip"). Very scanty literature is available on the diurnal BP pattern in healthy gravidae with uncomplicated pregnancy.

The aim of the study was to evaluate of the day-time/night-time mean arterial blood pressure (MAP) fall in pregnant woman in the first half of pregnancy in comparison with healthy non-pregnant women.

Fifty seven healthy woman were included into the study, and divided into two groups: 23 pregnant woman in 7-20 weeks of first gestation and 34 non-pregnant woman. All the subjects were included into the 24-hours non-invasive automated blood pressure monitoring (ABPM).

Nocturnal fall of BP appeared to be the most pronounced element of the circadian BP pattern in the studied women. Women in the first half of pregnancy exhibit reduction of BP in the night-time similar to that observed in the non-pregnant subjects. In average, 2/3 of pregnant women below 20 weeks of gestation belong to "dippers" in the MAP range. Women with higher mean diurnal BP value have less pronounced nocturnal BP "dip".