Draw Transcutaneous Bilirubin Nomogram for Evaluating Risk of Severe Jaundice and its Relationship with Maternal, Childbirth and Neonatal Factors in the Healthy Newborns 35 or Higher Weeks of Gestation

Abstract

Abstract: Background: Hyperbilirubinemia is one of the most common problem in newborns, and in most cases is benign. Because of the potential toxicity of bilirubin, monitoring of newborns can help identify those may be affected by sever hyperbilirubinemia and kernicterus. The purpose of this study was to construct percutaneous bilirubin nomogram in the healthy newborns 35 or higher weeks of gestation for predicting risk of severe jaundice and to identify of associated maternal, childbirth and neonatal factors with sever hyperbilirubinemia. Methods: This cross-sectional study was conducted on 1066 healthy infants with the gestational age of ≥35 weeks and birth weight of ≥2000 g. Before measuring of transcutaneous bilirubin (TCB), maternal, childbirth and neonatal questionnaire was completed using of maternal and neonatal records and interview with mother. The first measurement of TCB was performed before discharge and during 12-48 hours. Neonates were followed up after discharge till completion of 6th postnatal age, based on the age of the baby at the time of discharge. In this study, the neonates were diagnosed need phototherapy, based on TCB values and AAP phototherapy guidelines were referred to the pediatrician in the relevant unit for further examination and treatment. Infants according to discharge time transcutaneous bilirubin level and the infant’s age based in hours, the newborns were divided into four groups of low risk (40th), lower intermediate risk (40th -75th), upper intermediate risk (75th -95th) and high risk (≥90th). Then the percentage of infants who progressed to sever hyperbilirubinemia in each percentile was obtained. Data were analyzed using SPSS software version 24. For construction of nomogram, STATA software was used and to determine the relationship of maternal, childbirth and neonatal factors with sever hyperbilirubinemia and transcutaneous bilirubin level logistic regression and general linear model (unadjusted and adjusted to control confounding factors) were used. Results: According to transcutaneous bilirubin level at discharge time and the infant’s age in hours, bilirubin nomogram was constructed using 40th -75th -95th percentile. 389 infants (41.2%) in the low-risk group, 329 newborns (34.8%) in the lower intermediate risk group, 179 neonates (18.9%) in the upper intermediate risk group and 47 neonates (4.9%) in high risk group were classified. The risk of sever hyperbilirubinemia in followed up newborns was 48.9%, 14.5%, 9.7% and 3.3%, in groups from high risk to low risk. Of the cases of neonatal followed up, 850 newborns (90.04%) had no severe hyperbilirubinemia and 94 newborns (9.96%) had severe hyperbilirubinemia. Regarding to relationship between maternal, neonatal and childbirth characteristics with severe hyperbilirubinemia, based on the results of modified logistic regression, it was found that there was significant relationship between variables of living place, previous history of jaundice, giving water or sugar to the infant in breast feeding intervals, frequency of infant feeding, gestational age, maternal blood group, hospital discharge time and gravidity with severe hyperbilirubinemia (p<0.05). Also regarding to relationship between maternal, neonatal and childbirth characteristics with transcutaneous bilirubin level, based on the results of the general linear model, it was found that there was significant relationship between previous history of jaundice, infant age at first meconium excretion, frequency of infant feeding, gestational age, maternal blood group and number of ultrasounds in pregnancy with bilirubin level (p<0.05). Conclusion: Bilirubin nomogram can be used to predict severe hyperbilirubinemia in Iranian newborns. Current study needs to be done in a wider context in other provinces in order to prepare a complete, valid and standard Nomogram, and was implemented in Iran as a common practice. Also, some related maternal, neonatal, and childbirth factors with neonatal jaundice were identified in this study that provide information for the medical staff to identify the risk factors for jaundice and prevent its consequences.