Three principal kinds of hypertension may be encountered in pregnancy: (1) chronic hypertension preceding pregnancy; (2) pregnancy-induced hypertension superimposed on chronic; and (3) pregnancy-induced hypertension alone. The purpose of the present study was to investigate the influence of these three categories on fetal growth. The results of hypertensive pregnancies were compared with those of a normotensive control group. The effect of proteinuric hypertension on fetal growth was studied also.Data on hypertensive patients (716 nulliparae and 489 multiparae) and on the same numbers of matched normotensive controls were analyzed on a retrospective basis. Each hypertensive patient was assigned to one of three groups: group I (66 nulliparae and 73 multiparae) had chronic hypertension. Group II (25 nulliparae and 24 multiparae) had chronic hypertension with superimposed pregnancy-induced hypertension. Group III (625 nulliparae and 392 multiparae) had pregnancy-induced hypertension alone.The incidence of small-for-gestational-age infants (below the 5th percentile) in nulliparae is shown in Table 1, and that in multiparae is shown in Table 2. In both subgroups, the differences between controls and hypertensive patients with respect to the incidence of small-for-gestationalage infants were significant (nulliparae, P = 0.0012; multiparae, P 10−4). The differences among the three kinds of hypertension were significant in the multiparae subgroup (P = 0.0024) but not in the nulliparae subgroup (P = 0.21).The total number of nulliparae with diastolic blood pressure of 90 mm Hg or more before the 20th week of gestation equalled 91 (groups I and II, Table 1). Of these 91 patients, 25 (27.5 per cent) developed superimposed pregnancy-induced hypertension (group II, Table 1). The total number of multiparae with diastolic blood pressure of 90 mm Hg or more before the 20th week of gestation equalled 97 (groups I and II, Table 2). Of these 97 patients, 24 (24.7 per cent) developed superimposed pregnancy-induced hypertension.The relative incidence of proteinuria increased progressively with an increase of maximum diastolic blood pressure levels in both nulliparae and multiparae. In patients with proteinuric hypertension, the incidence of small-for-gestational-age infants was significantly higher when compared with that in non-proteinuric patients (16.9 per cent vs. 11.7 per cent; P = 0.044). The differences, however, were not significant when the proteinuric group was compared with the nonproteinuric group at a given level of maximum diastolic blood pressure (i.e., when maximum diastolic blood pressure levels were standardized).When patients with pregnancy-induced hypertension (group III) were singled out, the incidence of small-for-gestational-age infants was not significantly higher in the proteinuric group as compared with that in the nonproteinuric group (13.4 per cent vs. 11.0 per cent; P = 0.51). The same was true when maximum diastolic blood pressure levels were standardized. When various factors (parity, kind of hypertension, maximum diastolic blood pressure level, and presence of proteinuria) were considered simultaneously, only maximum diastolic blood pressure level proved to have an association with the incidence of small-for-gestational-age infants (P 10−4). The number of patients in groups I and II was too small to allow calculation of the risk of small-for-gestational-age infants separately in the absence or presence of proteinuria with standardized blood pressures.
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