[Incidence and fetal impact of hypertension in pregnancy: study of 2996 pregnancies].

To evaluate the incidence and the foetal effects of gestational hypertension, we studied 2 996 pregnancies with a single live birth in mothers selected on the basis of 1) a documented diastolic blood pressure (DBP) less than 90 mmHg before the 16th week of amenorrhea and 2) no history of hypertension or kidney disease. In 38,4% of the gravidas, the highest DBP during pregnancy was greater than or equal to 90 mmHg, and in 15,4% this level was reached twice or more. Gestational hypertension (two DBP readings greater than or equal to 90 mmHg) was more frequent in nullipara than in mothers with previous pregnancies (17,9 versus 12,4%, p less than 0,01) and its incidence tended to decrease with increasing maternal age. Irrespective of parity or maternal age, a significant increase in the percentage of small for gestational age infants was associated with increasing DBP levels: 3,2, 6,4 and 8,5% when the highest recorded DBP was less than 90 mmHg, equal to 90 mmHg (even at one single reading), or greater than or equal to 100 mmHg respectively (p less than 0,001). Very similar percentages were obtained in non-proteinuric pregnancies: 3,3, 6,5 and 7,8 respectively (p less than 0.001). Non-proteinuric gestational hypertension, even mild or transitory, is indicative of a high risk pregnancy and requires close medical supervision.