In the past, an adverse prognostic significance of an altered left ventricular geometry in essential hypertension has been demonstrated. There are no data on the prognostic significance of an altered cardiac structure during pregnancy. The present study was designed to evaluate the prognostic impact on the outcome of pregnancy of an altered geometry of the left ventricle in mild gestational hypertension. One hundred forty-eight consecutive, pregnant, mild gestational hypertensive women (systolic and diastolic blood pressure, 140 to 150 mm Hg and 90 to 99 mm Hg, respectively) were included in the study. Patients were monitored until term to detect subsequent fetal and/or maternal adverse outcomes (preeclampsia, preterm delivery, abruptio placentae, other maternal medical problems, fetal distress, neonatal low birth weight, admittance to neonatal intensive care unit). One hundred one gestational hypertensive patients (68.2%) had an uneventful pregnancy; 47 patients (31.8%) showed a subsequent development of maternal and/or fetal complications. Concentric geometry was prevalent among patients with the subsequent development of complicated gestational hypertension (37 out of 47 patients) compared with the uneventful gestational hypertensive patients (31 out of 101 patients; 78.7% versus 30.1%; P=0.0001). The multivariate analysis showed concentric geometry as an independent predictor of adverse outcomes (odds ratio, 3.65; 95% confidence interval, 1.30 to 10.27; P=0.014). In patients with gestational hypertension, blood pressure values alone appear to be insufficient to identify the effective risk of adverse events. Ventricular geometry gives additional prognostic information, possibly improving our clinical ability to follow and eventually treat these patients.