The most recent Cochrane reviews on oral antihypertensive drugs in pregnancy conclude
that no substantial benefits for the mother or fetus are demonstrated so far. Whether this applies for a
high-risk and diabetic pregnancy is doubtful. The aim of this short review is an introduction to the
field of ambulatory blood pressure measurements in pregnancy and in particular in women with type 1
diabetes. Diabetic pregnancy is complicated with a 50% risk of hypertension/preeclampsia. In the nonpregnant,
diabetic women minute increases in blood pressure as well as in albuminuria are forerunners
for incipient and overt nephropathy. Medication is essential and can conserve renal function, modifying
the risk of renal insufficiency. During pregnancy, renal insufficiency in women with diabetes leads to
termination of pregnancy. Therefore, detection of minute changes based on reliable measurements in this high-risk population
is invaluable to protect the mother’s kidney function and, if possible, prolong pregnancy for the benefit of the fetus.
Estimates of risk by blood pressure evaluation in these women are influenced by pregnancy per se and diabetes
vasculopathy. Several factors have to be considered as few monitors are validated for use in pregnancy and not many of
the different methodologies have undergone thorough investigation. The use of absolute values of blood pressure have the
advantage that fewer assumptions are necessary on how blood pressure behaves due to modes of evaluation and biological
rhythm. Monitors should be chosen with care considering the clinical setting, timing, and population, which influences the
outcome, thus, the monitors ought to be validated for the specific condition they are applied for. The strategy for the
studies used for safe conclusions in this brief review was chosen with priority of the papers with the best, validated
methodology on BP measurements, which is by no way guaranteed in numerous recent publications.
Inherent characteristics of the measurements to be considered are reproducibility, consistency, precision, and trend over
scale of measurement. Studies on these issues suggest that consistency and precision depend on which monitor is used.
During pregnancy, the reproducibility and specificity depend on the timing and whether measurements are performed
repeatedly. Over- and underestimations of blood pressure are typical for 24-h monitoring in high- as well as low risk
Preeclampsia is associated with urinary albumin excretion rate, reduced night/day ratio, and elevated diurnal blood
pressure from first trimester and onwards. However, due to blunting of the diurnal variation, the night/day rhythm
provides no good prediction of preeclampsia. Diurnal measurement is a valuable estimate of blood pressure in terms of
sensitivity, specificity, and predictive values.