Ma. Brown et al., AMBULATORY BLOOD-PRESSURE MONITORING IN PREGNANCY - WHAT IS NORMAL, American journal of obstetrics and gynecology, 178(4), 1998, pp. 836-842
OBJECTIVE: Noninvasive 24-hour ambulatory blood pressure monitoring ho
lds great promise as a useful tool in the management of hypertensive p
regnancies and pregnancies considered ''at risk'' for development of p
reeclampsia. The purpose of this study was to define ambulatory blood
pressure monitoring parameters throughout normal pregnancy, including
women considered at risk for development of hypertension who continued
to have a completely normal pregnancy. STUDY DESIGN: Two hundred seve
nty-six 24-hour ambulatory blood pressure monitoring studies were made
cross-sectionally with use of a Spacelabs 90207 device (validated for
use in pregnancy), at one or more of 9 to 17, 18 to 22, 26 to 30, and
>30 weeks' gestation. Upper limits of normal were defined as the mean
plus 2 SDs for awake and sleep ambulatory blood pressure monitoring r
esults at each stage. RESULTS: Average awake upper limits of normal we
re 130/77, 132/79, 133/81, and 135/86 mm Hg at the four stages of preg
nancy, respectively. Systolic blood pressure fell significantly by 12%
to 14% (p < 0.0001) and diastolic blood pressure by 18% to 19% (p < 0
.0001) during sleep at all stages of pregnancy. Awake ambulatory blood
pressure monitoring systolic measurements were 11 to 12 mm Hg higher
than ''clinic'' measurements (p < 0.001) and diastolic measurements we
re 5 to 11 mm Hg higher (p < 0.0001) throughout pregnancy. Maximum blo
od pressure variability ranged from 8 to 13 mm Hg. CONCLUSIONS: The up
per limits of normal ambulatory blood pressure monitoring-derived meas
urements rise slightly as pregnancy progresses. Awake measurements are
higher than ''clinic'' measurements recorded under relaxed conditions
by a clinical researcher. The diurnal blood pressure fall and variabi
lities are similar during pregnancy to those seen in nonpregnant subje
cts. These data should provide valuable references for further studies
of ambulatory blood pressure monitoring in high risk pregnancies.