Objective. To evaluate the effect of antenatal phenobarbital (PB) ther
apy on neonatal intracranial hemorrhage (ICH) in preterm infants. Desi
gn. Prospective, randomized, controlled trial. Setting. Single institu
tion study. Subjects and Interventions. Women in preterm labor (<35 we
eks' gestation) were assigned to control and treatment groups. The tre
atment group received 10 mg/kg (maximum, 1000 mg) PB intravenously, fo
llowed by 100 mg orally daily, until delivery. Neonates did not receiv
e PB after birth. Head sonograms were performed on days 3, 7, and 14 a
nd at discharge. Hemorrhage was classified as mild, moderate, or sever
e by a single reader. Outcome Measures. Incidence of neonatal ICH in a
ll infants, infants weighing less than 1250 g, and infants of multiple
gestations. Results. The study population comprised 110 women, 60 in
the control group and 50 in the PB group. Neonates in the control grou
p (n = 74, including 10 pairs of twins and 2 sets of triplets) were co
mparable to those in the treatment group (n = 62, including 7 pairs of
twins, 1 set of triplets, and 1 set of quadruplets) regarding birth w
eight, gestational age, and other clinical risk factors for ICH. There
was a trend for the incidence of any grade of hemorrhage to be lower
in the PB group (22% [14 of 62]) compared with the control group (35%
[26 of 74]). Moderate and severe hemorrhages were significantly lower
in the PB group (1.6% [1 of 62]) compared with the control group (9.4%
[7 of 74]). Among infants weighing less than 1250 g, overall ICH was
lower in the PB group (23% [6 of 26]) compared with the control group
(51% [18 of 35]). Among multiple-gestation infants, overall ICH was 4.
7% (1 of 21) in the PB group, compared with 31% (8 of 26) in the contr
ol group. Conclusions. Antenatal PB therapy results in a significant d
ecrease in moderate and severe ICH in infants born at less than 35 wee
ks' gestation. Antenatal PB therapy also resulted in a decrease in the
incidence of all grades of ICH in infants weighing less than 1250 g a
nd infants born of multiple gestations.