Improvement in control of maternal blood pressure with use of beta-blockers would be worthwhile only if it were reflected in substantive benefits for mother and/or baby, and none have been clearly demonstrated. The effect of beta-blockers on perinatal outcome is uncertain; the worrying trend to an increase in SGA infants is partly dependent on one small outlying trial. Large randomised trials are needed to determine whether antihypertensive therapy in general (rather than beta-blocker therapy specifically) results in greater benefit than risk, for treatment of mild-moderate pregnancy hypertension. If so, then it would be appropriate to consider which antihypertensive is best, and beta-blockers should be evaluated.
[Note: the seventeen reports in the awaiting classification section of the review may alter the conclusions of the review once assessed.]
Neonatal adaptation in hypertensive pregnancy--a study of labetalol vs hydralazine treatment.
Twenty mothers with moderate to severe preeclampsia were allocated to labetalol (Trandate) or hydralazine (Apresolin) antihypertensive treatment. Arterial blood gas analysis was performed at delivery from the clamped cord. Neonatal blood pressure, heart rate and axillary temperature were registered 0.5, 2, 6, 12, 24, 36, 48 hours and 3, 4 and 7 days after birth. Respiratory rate was registered at the same intervals until 36 hours after birth. Blood glucose levels were measured 2, 6, 12 and 24 hours after birth. Peripheral blood flow in the calf was measured at 24 hours of age. Gestational age did not differ between the two groups; 36 (27-40) in the labetalol, and 35 (29-37) weeks in the hydralazine group (median and range). Median cord pH was lower, and the number of infants with a cord pH < 7.20 was higher in the hydralazine group. Blood glucose levels were lower in the labetalol group at 6 hours of age (p < 0.05). No other differences were found between the two groups. The conclusion is that no clinical signs of adrenergic blockade have been found at 24 hours of age, and no negative effect of labetalol on the neonatal adaptation compared to hydralazine antihypertensive treatment was found.