Original Article Transient gestational hypertension: Not always a benign event T. Lee-Ann Hawkins a , Mark A. Brown b,c,⇑ , George J. Mangos b,c , Gregory K. Davis b a Departments of Medicine and Obstetrics and Gynaecology, University of Calgary, Alberta, Canada b Department of Women’s Health, St. George Hospital, University of New South Wales, Kogarah, NSW, Australia c Departments of Renal Medicine and Medicine, St. George Hospital, University of New South Wales, Kogarah, NSW, Australia article info Article history: Received 27 May 2011 Received in revised form 17 August 2011 Accepted 2 September 2011 Available online 15 September 2011 Keywords: Transient gestational hypertension Pregnancy Preeclampsia Gestational hypertension abstract Objective: Pregnancy outcome in women with transient gestational hypertension (TGH), defined as de novo blood pressure elevation after 20 weeks gestation that normalizes by subsequent evaluation in a Day Assessment Unit. Study design: Retrospective cohort analysis of hypertensive pregnancies between 2003 and 2008. Main outcome measures: Final hypertensive delivery diagnosis and composites of adverse maternal and fetal outcome. Results: Overall 1417 women were referred; 890 met criteria; 41% (65% of study popula- tion) had TGH. Twenty percent with TGH developed gestational hypertension and 19% pre- eclampsia. Women with TGH who developed preeclampsia had similar composite adverse maternal outcomes to other preeclamptic women (51% vs. 63%; p = 0.24) but fewer adverse fetal outcomes (50% vs. 71%; p < 0.01) due to less prematurity (30% vs. 45%; p = 0.02) and small for gestational age babies (33% vs. 51%; p = 0.02). Within the TGH population, devel- oping gestational hypertension or preeclampsia was associated with referral at gestation <33 weeks (RRR 2.8; p < 0.01), initial average systolic blood pressure 130–139 mmHg (RRR 2.1; p < 0.01) and initial average diastolic blood pressure 80–89 mmHg (RRR 3.2; p < 0.01). Conclusion: TGH after 20 weeks is common in pregnancy. Although initial assessment implies low risk, the risk of progression to gestational hypertension or preeclampsia is sub- stantial and warrants appropriate clinical surveillance. Ó 2011 Published by Elsevier B.V. on behalf of International Society for the Study of Hypertension in Pregnancy. Introduction The hypertensive disorders of pregnancy, which include pre-existing or chronic hypertension, white-coat hyperten- sion, gestational hypertension and preeclampsia, affect up to 10% of all pregnancies and are the leading cause of both maternal and fetal morbidity and mortality [1]. Much ef- fort has been placed on trying to predict which pregnan- cies will be affected by hypertension, in particular preeclampsia as it is the pregnancy-specific disease which is largely responsible for poor pregnancy outcome [2,3]. There has been considerable interest in clinical and lab- oratory indices that can be used to stratify women accord- ing to their risk of progression to preeclampsia [4,5]. Nevertheless, de novo hypertension, i.e., blood pressure elevation in a previously normotensive woman, remains the most common presentation of preeclampsia. It is widely accepted that women with pre-existing chronic hypertension have an increased risk of developing preeclampsia when compared to the baseline normoten- sive pregnant population [6]. Studies have also shown that women with white-coat hypertension in the first half of pregnancy (persistently elevated blood pressure in the 2210-7789/$ - see front matter Ó 2011 Published by Elsevier B.V. on behalf of International Society for the Study of Hypertension in Pregnancy. doi:10.1016/j.preghy.2011.09.001 Abbreviations: TGH, transient gestational hypertension. ⇑ Corresponding author at: Department of Renal Medicine, St. George Hospital, Kogarah, NSW 2217, Australia. Tel.: +61 2 9113 2622. E-mail address: mbrown@unsw.edu.au (M.A. Brown). Pregnancy Hypertension: An International Journal of Women’s Cardiovascular Health 2 (2012) 22–27 Contents lists available at SciVerse ScienceDirect Pregnancy Hypertension: An International Journal of Women’s Cardiovascular Health journal homepage: www.elsevier.com/locate/preghy