Abstract:
Objective White coat hypertension (WCH) is a common phenomenon with a long term prognosis intermediate
between those with true hypertension and true normotension. The natural history of this phenomenon
throughout pregnancy remains unknown. We assessed the likelihood of women with an initial diagnosis of
WCH developing pre-eclampsia (PE) as their pregnancy progressed.
Design Prospective observational study.
Setting St George Hospital, a teaching and University hospital.
Population Two hundred and forty-one pregnant women with an early pregnancy diagnosis of essential
hypertension (EH).
Methods Eighty-six women had this diagnosis (EH) confirmed pre-pregnancy by 24-hour ambulatory blood
pressure monitoring (ABPM) or repeated automated home blood pressure (BP) self-measurement. The
remaining 155 underwent 24-hour ABPM in early pregnancy to establish their diagnosis. Women found to
have WCH did not receive antihypertensives during their pregnancy, whereas those with confirmed EH
received oxprenolol or methyldopa. Women with WCH had repeated 24-hour ABPM and/or BP assessments
in a pregnancy day assessment unit until delivery.
Main outcome measure The development of PE in women with WCH or EH.
Results The overall prevalence of WCH was 32%. Half retained this phenomenon throughout pregnancy and
had good pregnancy outcomes. Forty percent developed (benign) gestational hypertension and also had good
pregnancy outcomes while 8% developed proteinuric PE, significantly fewer than in women with confirmed
EH (22%), P = 0.008. No BP parameter at study entry permitted discrimination between those women with
WCH who retained this phenomenon and those who developed GH or PE.
Conclusion WCH is a common phenomenon in pregnant women who appear to have EH according to routine
BP measurement early in pregnancy. Antihypertensives may be withheld from this group initially and they
can be advised they will have better pregnancy outcomes than women with true EH. However, continued
monitoring throughout pregnancy remains important to detect the small group of white coat hypertensives
who develop PE.
