In a prospective study, women who were hypertensive before the 28th wk of gestation were randomly allocated into two groups: those who received specific hypotensive therapy (Ht) and those who did not (Hu). The outcome was compared with a random sample of the hospital population (S) ascertained after delivery. In both hypertensive groups there was a higher incidence of clinical signs of possible fetal distress and instrumental delivery. Although there was no difference between the groups in the distribution of birthweight above and below the mean for gestational age, the treated hypertensive group had an excess of infants with relatively smaller head circumferences for their gestational age compared with both the untreated hypertensive group and the hospital sample. Tube-feeding was also more frequent in the treated hypertensive group. In the untreated hypertensive group there were more infants whose neurological status was categorized as questionable or abnormal in the neonatal period, compared with the sample. The different problems encountered by infants in the two hypertensive groups emphasized the need for further study of these babies. Their development during the first year of life will be examined in a subsequent paper.