Objective To determine the likelihood of progression from gestational
hypertension (GH) to preeclampsia (PE) in hypertensive pregnant women
and whether this change can be identified in advance by available clin
ical and laboratory measures. Design A retrospective analysis and a pr
ospective study. Setting St George Hospital, Sydney, a teaching hospit
al of the University of New South Wales delivering 2500 women per year
. Population Eight hundred and forty-five women with new hypertension
in the second half of pregnancy, managed by a uniform protocol (661 in
the retrospective analysis, 184 in the prospective study). Methods Cl
inical and laboratory data at initial presentation were compared among
women with GH who developed PE and those who remained with a diagnosi
s of GH until delivery. Data predictive for progression from GH to PE
were analysed by logistic regression analysis. Main Outcome Measured P
rogression from GH to PE. Results In the retrospective analysis, 416 w
omen initially presented as having GH and 62 (15%) progressed to PE. I
n the prospective study, 112 women initially presented with GH and 29
(26%) progressed to PE, giving an overall progression of 17%. In both
studies, women who developed PE from GH presented earlier than those w
ho remained with GH until delivery. In multiple logistic regression an
alyses prior miscarriage and early gestation at presentation were asso
ciated with increased likelihood of progressing from GH to PE. Conclus
ion Approximately 15-25% of women initially diagnosed with GH will dev
elop PE and this is more likely with earlier presentation or if the wo
man has had a prior miscarriage. Women with gestational hypertension d
iagnosed after 36 weeks of gestation have only about 10% risk of devel
oping PE. These data should help stratify the risks of mildly hyperten
sive pregnant women being managed as outpatients in their third trimes
ter.