Pediatr. Res. 14: 947-952 (1980) fetus neonate hyperbilirubinemia phenobarbital Effectiveness and Safety of Prenatal Phenobarbital for the Prevention of Neonatal Jaundice T. VALAES,'~'K. KIPOUROS, S. PETMEZAKI, M. SOLMAN, AND S. A. DOXIADIS Institute of Child Health, Athens, Greece Summary be denied on the basis that such effects have not been observed following therapeutic use of PB in the perinatal period. For this The effect of 100 mg of phenobarbital (PB) at bedtime for the reason, 5 years after the completion of the initial study, a follow- last few wk of pregnancy on the incidence and severity of neonatal up examination of the children exposed to prenatal PB was carried hyperbiirubinemia was studied. No effect was observed in the out with the aim of answering the question of the long-term effects newborns of mothers who took less than ten tablets. In the 1310 of such a preventive treatment (36). newborns of adequately treated mothers (PB 1 1.0 g), the inci- dence of marked jaundice (bilirubin > 16.0 mg/dl) and the need to perform an exchange transfusion were reduced by a factor of six MATERIALS AND METHODS in relation to the incidence in 1553 control infants. A randomly selected group of 415 children (182 control, 233 PB) INITIAL STUDY were reexamined at 61 to 82 months of age. There was no Between October, 1968, and November, 1971, in two areas of difference in the overall morbidity and mortality between the Greece, the island of Lesbos and the city of Athens, pregnant control and treatment group. A detailed neurologic assessment women after informed consent participated in a controlled blind failed to reveal any differences between the two groups. In the trial of PB. The methodology of the trial was described in detail VisuoMotor Integration test, the PB group scored significantly elsewhere (35). In the treatment group, a tablet of 100 mg PB was better than the control group. In the Draw-A-Woman and the taken at bedtime for a variable period (maximum for 8 wk) Verbal Intelligence Test, the difference was in the same direction depending on the interval between the prenatal visit at 34 to 36 but was not statistically significant. The degree of jaundice was wk of gestation and delivery. The control group received placebo not found to significantly influence the performance in the neuro- tablets (Phase I). After the efficacy of PB and the absence of logical examination and the intelligence tests. Sensorineural hear- immediate untoward effects were demonstrated (35), all the ing defect was significantly more common in the children with women who attended for prenatal examination in their last 4 to 6 moderate or marked jaundice (bilirubin > 12 mg/dl) than in those wk of pregnancy were given PB, whereas those who missed for with lesser degrees of jaundice. one reason or another this prenatal examination were included in Prenatal PB is a practical, effective, and safe method for the control group (Phase 11). This change in methodology was decreasing the incidence of neonatal hyperbilirubinemia. dictated by the need to provide an effective prevention of severe neonatal jaundice to this population experiencing both a high risk (7, 33) and considerable difficulties with the alternative treatment Speculation by exchange transfusion. It was realized that this change was A wide variety of substances to which populations are exposed going to affect the comparability of the two groups with an excess like alcohol and pesticides share with phenobarbital the ability to of women from rural areas and lower socioeconomic classes induce liver enzymes. It is possible that part of the variability in expected in the control group. Nevertheless, because the immedi- the ability of newborns to eliminate bilirubin is due to differences ate aim was to assess the practical impact and to exclude uncom- in exposure during fetal life to environmental inducing agents. mon complications of the treatment, both unlikely to be related to social class or place of domicile, we decided it was worthwhile to continue collecting data. The ability of newborns to eliminate bilirubin is limited to a Cord blood was collected from all newborns for blood typing, varying degree, and this is a major factor in the pathogenesis of direct Coombs test, and screening for G-6-PD deficiency (19). neonatal unconjugated hyperbilirubinemia (8). Phenobarbital During Phase I, venous blood samples were drawn between 24 (PB) was found effective in decreasing the level of bilirubin in and 48 hr after birth (first or second day of life) and on the fourth individuals with genetically determined decreased bilirubin con- day of life. Consent for drawing one or both of these venous jugation (2. 6, 16. 37). and Trolle (30). in a retrospective study, samples was refused on a few occasions. Bilirubin measurements found diminished incidence of neonatal jaundice in infants of were performed in all blood samples using either the method of epileptic women treated with PB. Several studies demonstrated Malloy and Evelyn (17) or the direct reading Bilirubinometer the effectiveness of prenatal PB in reducing neonatal hyperbili- (American Optical Co., Buffalo, NY). Initial comparison as well rubinemia (18, 23, 26, 30, 31). Because of the small number of as regular checking throughout the study period using "Versatol subjects and the relative low risk of kernicterus in the populations Pediatric" (Warner Lambert Co., Morris Plains, NJ) standard studied, no proper assessment of the impact of such a preventive showed that the two methods gave comparable results. treatment on the overall problem of neonatal jaundice and its During Phase 11 of the trial, no routine venous samples were sequelae could be made. The present study provides this assess- drawn, but bilirubin measurements were done as frequently as ment in a large population of Greek newborns in which previous required in infants with moderate or marked jaundice. studies have shown an increased frequency of marked jaundice Throughout the study, the newborns were examined clinically and kernicterus (7, 33). daily, and the degree of jaundice was recorded. The physician Exposure to an agent during the fetal or newborn period responsible for this examination was unaware of whether the invariably raises the spectrum of unsuspected long-term untoward infant was in the control or PB group, and he was not responsible effects. The possibity of long-term undesirable effects of PB cannot for the clinical management of the newborns. None of the infants 9 4 7 948 VALAES ET AL. was treated with phototherapy, and vitamin K was not given lirubinemia. In the group of term infants with no blood group routinely at birth. incompatibility and normal G-6-PD activity in which bilirubin was measured routinely (phase I), a significant difference was FOLLOW-UP STUDY present even in the cord blood (control, 1.69 + 0.57 mg/dl; PB, 1.36 f 0.92 mg/dl; P < 0.001), and by the fourth day of life, the From the children of the original study, we chose to reexamine mean bilirubin value of the control group (9.45 f 5.43 mg/dl) was those living in the island of Lesbos as they constituted a relatively double the value of the PB group (4.76 + 4.06 mg/dl; P < 0.001). "captive" population with the additional advantage of small vari- Table 1 presents the incidence of marked jaundice (bilirubin ation in socioeconomic and cultural conditions. For practical > i6.0 mg/dl) and exchange transfusion (performed when BR 2 reasons, it was impossible to reexamine the total population. To 25 mg in term infants without hemolytic disease). PB reduced the secure an unbiased and informative sample, the following proce- incidence of marked jaundice and the need for exchange transfu- dure was established. All the children of Phase I were designated sion among infants with nonspecific hyperbilirubinemia by a for follow up. The children of Phase I1 were tabulated according factor of six. In infants with ABO fetomaternal incompatibility, to the family's place of residence which was classified as either the incidence of marked jaundice was reduced by a factor of three urban, semirural, or rural, and the number of infants randomly whereas exchange transfusion was reduced by a factor of ten. All selected from each area was proportional to the registered number the three infants of the PB group that required exchange transfu- of inhabitants. Finally, any child not included in the previous sion were from Lesbos and had ABO incompatibility. In addition, groups but with marked jaundice in the neonatal period was also one was G-6-PD deficient, and the other had Down's syndrome designated to be reexamined. and polycythemia. Altogether, there were 5 infants with Down's After the list of children to be followed up was completed, the syndrome, and of these, 3 developed marked jaundice, and 2 families were contacted by mail. Whenever there was no response, required exchange transfusion. the local physicians, midwives, district nurses, or teachers were More males than females developed marked jaundice and re- used to contact or obtain information about the family. Our team quired exchange transfusion, but this difference did not reach a visited the towns and villages and examined the children in the level of statistical significance. In the control group, the incidence local hospital, rural dispensary, or school. Those responsible for of exchange transfusion was significantly higher (P < 0.05) in the examination had no access to the neonatal data. Lesbos than in Athens for infants with nonspecific hyperbilirubi- The examination protocol included 137 precoded items and in nemia as well as for those with ABO incompatibility. No difference many respects followed the protocol of the seventh year exami- was found in the incidence of jaundice in relation to the rural or nation of the Perinatal Collaborative Project of the National urban place of domicile in the island of Lesbos.