Factors influencing the incidence of neonatal jaundice

Fetal and neonatal bilirubin metabolism

Human fetal and neonatal bilirubin metabolism is centered on 4Z,15Z-bilirubin IXα (BR) due to the extremely low BR conjugating capacity of the liver. BR is a unique, highly lipophilic substance with physiological and toxic effects in the cell membranes of organs and body tissues. The fetus excretes BR through the placenta to the maternal circulation. After birth, BR is thought to act as an antioxidant against the increase in reactive oxygen species caused by the rapid increase in oxygen concentration during the adaptation process from in amniotic fluid to in air. However, bilirubin encephalopathy is a toxic effect of bilirubin. Due to the lipophilic nature of BR, it must be bound to a carrier to be distributed to various parts of the body by hydrophilic blood. This carrier of BR is human serum albumin (HSA). In humans, BR can be excreted efficiently after undergoing photochemical reactions upon high affinity binding to HSA. HSA also plays an important role in the prevention of bilirubin encephalopathy. This review focuses on the developmental and physiological role of bilirubin metabolism during the fetal and neonatal periods.

Effects of Season of Birth and Meteorological Parameters on Serum Bilirubin Levels during the Early Neonatal Period: A Retrospective Chart Review

To establish whether serum bilirubin levels vary in healthy term neonates according to seasonal variations and meteorological factors, we retrospectively studied 3344 healthy term neonates born between 2013 and 2018. Total serum bilirubin (TSB) levels were measured on the fourth day after birth. The monthly and seasonal variations in TSB levels and clinical and meteorological effects on TSB levels were assessed. In the enrolled neonates, the median TSB level was 195 µmol/L. The TSB level peaked in December and was the lowest in July, but the variation was not statistically significant. The TSB level was significantly higher in the cold (October to March) than in the warm season (April to September; p = 0.01). The comparison between seasonal differences according to sex showed TSB levels were significantly higher in the cold than in the warm season in male infants (p = 0.001), whereas no significant difference was observed in female infants. A weakly negative but significant association existed between TSB levels and the mean daily air temperature (r = -0.07, p = 0.007) in only the male population; the female population showed no significant correlation between TSB levels and meteorological parameters. The season of birth is an etiological factor in neonatal jaundice, with an additional influence from sex.

Prevalence and risk factors for hyperbilirubinemia among newborns from a low-risk birth setting using delayed cord clamping in Japan

AIM

Neonatal jaundice is a common problem among infants. Among the several risk factors are East Asian race and delayed cord clamping. Birth centers manage low-risk term deliveries using physiological management, which may include delayed cord clamping. This study aimed to investigate the occurrence of hyperbilirubinemia, a pathological process of jaundice, and its risk factors among neonates born at a Japanese birth center.

METHODS

This was a retrospective cohort study. Data were collected from March 2006 to October 2014 from healthy mothers and neonates at a birth center in a metropolitan area of Japan. Demographic data and background factors of hyperbilirubinemia, including blood and transcutaneous values of jaundice, were collected and statistically analyzed.

RESULTS

Of the 1,211 neonates analyzed, 4.7% exceeded the standard transcutaneous bilirubin value, and 1.8% needed phototherapy. Multiple logistic regression with adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) was used to identify the risk factors of hyperbilirubinemia, which were found to be cephalohematoma (OR = 30.18, 95% CI 5.63-161.69), delay of meconium elimination (OR = 2.66, 95% CI 1.28-5.51), previous history of phototherapy of siblings (OR = 10.28, 95% CI 3.53-29.92), and primiparity (OR = 4.55, 95% CI 2.59-8.02).

CONCLUSIONS

In low-risk Japanese neonates delivered at a birth center expected to practice delayed cord clamping, the rate of neonates requiring phototherapy was not high compared to previous studies, and the identified risk factors of hyperbilirubinemia were related to bilirubin metabolism.

Beyond "Asian": Specific East and Southeast Asian Races or Ethnicities Associated With Jaundice Readmission

OBJECTIVES

Clinical practice guidelines have recognized "Asian" and "East Asian" as risk factors for newborn jaundice and readmission. We sought to identify more detailed and specific, parent-identified races or ethnicities associated with jaundice readmission.

METHODS

We conducted a case control study of 653 newborn infants born (2014-2016) at a West-Coast, urban hospital to examine specific parent-described races or ethnicities that are associated with newborn hospital readmissions for hyperbilirubinemia. Parent-reported race or ethnicity was abstracted from the California Newborn Screening Test.

RESULTS

Our sample included 105 infants readmitted for jaundice (cases) and 548 infants as controls. In the full cohort, 66 infants (10.1%) were Coombs positive, 39 infants (6.0%) were born before 37 weeks' gestational age, and 405 infants (62.0%) were born to first-time mothers. The parents described the 653 infants using 45 unique races and ethnicities. In a multivariable model that controlled for Coombs positivity, gestational age <37 weeks, and primiparity, infants described as "Far East Asian" (odds ratio [OR] = 3.17; 95% confidence interval [CI] = 1.94-5.18) or "Southeast Asian" (OR = 3.17; 95% CI = 1.66-6.08) had increased risk for jaundice readmission. Infants described as Southeast Asian (eg, Laotian, Cambodian, Indonesian, Vietnamese, and Filipino) and Far East Asian (eg, Chinese, Korean, Taiwanese, Japanese, and Mongolian) had an increased risk of readmission. Finally, we did not find an association between South Asian (OR = 0.79; 95% CI = 0.33-1.92) race or ethnicity and risk of jaundice readmission.

CONCLUSIONS

In this study, we help clarify and move beyond the term "Asian" as a risk factor for readmission due to hyperbilirubinemia.

Phototherapy is commonly used for neonatal jaundice but greater control is needed to avoid toxicity in the most vulnerable infants

AIM

Limited information is available about how guidelines on phototherapy for neonatal jaundice are applied in practice and toxicity is a concern. We studied the use of phototherapy in relation to birthweight and gestational age (GA) in Norwegian neonatal intensive care units (NICUs).

METHODS

The study population was all 5382 infants admitted to the 21 NICUs in Norway between September 1, 2013 and August 31, 2014. Data were recorded daily in the Norwegian Neonatal Network database and anonymised data on patient characteristics, diagnoses, duration, the ages at the start and discontinuation of phototherapy were analysed.

RESULTS

More than a quarter (26.6%) of all infants admitted to Norwegian NICUs during the study period received phototherapy. The use of phototherapy was inversely related to GA and birthweight. More than 80% of the preterm infants under 28 weeks of GA received phototherapy. The duration was significantly longer in the lowest birthweight and GA groups and decreased with increasing birthweight and GA.

CONCLUSION

Phototherapy is proved to be a strong candidate for the most common therapeutic modality in NICU infants. However, in the light of reported toxicity in the smallest, most vulnerable infants, we recommend increased emphasis on quality control.

Neonatal jaundice and the immigrant population: A comparison study at a low-risk maternity ward in Norway

The aim of this study was to examine differences in distribution of neonatal jaundice by migration indicators. In this population-based study at the low-risk maternity ward at Baerum Hospital in Norway, 11,516 mother–child pairs were enrolled and divided into 7 groups by regions/country of origin. First registered live birth babies of mothers who gave birth between 1 January 2006 and 31 December 2010 were included. The study found that a total of 769 infants were treated for neonatal jaundice. Compared to Norwegians, infants born to mothers from East, Southeast and Central Asia had an increased risk and African infants had a decreased risk of neonatal jaundice. Jaundiced infants of African origin were more often transferred to neonatal intensive care units. Ethnicity is an important factor affecting the risk of neonatal jaundice requiring hospitalization in our clinic. To reduce this risk, parents should be adequately informed about the signs of neonatal jaundice requiring medical intervention.

Does gender affect neonatal hyperbilirubinemia in low-birth-weight infants?

BACKGROUND

Neonatal mortality and morbidity are gender-biased in low-birth-weight (LBW) infants. The male disadvantage theory has been suggested to be responsible for these maturational differences.

OBJECTIVE

To examine the impact of gender on neonatal hyperbilirubinemia.

DESIGN/METHODS

A retrospective observational study. Data on all LBW infants admitted to George Washington University neonatal intensive care unit and surviving for >48 hrs from January 1992 to March 2003 were analyzed. Males and females were compared for gestational age, birth weight, race, Apgar scores at 1 and 5 mins, peak bilirubin levels, sepsis, and intraventricular hemorrhage (IVH). Significant differences were entered in a regression model to detect the influence of gender on bilirubin (Bili). Analysis was repeated after stratification of infants into: group A, <1000 g; group B, 1000-1499 g; and group C, 1500-2499 g.

RESULTS

A total of 840 infants were included in this study. When comparing males (n = 407) with females (n = 433), significant differences were detected in birth weight (1,539 +/- 541 vs. 1,428 +/- 549 g; p = .003), IVH (14.2% vs. 9%; p = .025), and Bili (10.1 +/- 3.0 vs. 9.2 +/- 2.8 mg%; p < .001). No differences were detected in gestational age, sepsis, or Apgar 1 and 5. Difference in Bili for the entire group remained significant in the regression model (regression coefficient [RC] = 0.79 +/- 0.22; p < .001). In subgroup analyses: group A Bili (8.4 +/- 2.3 vs. 8.0 +/- 2.0; p = .14) and group B Bili (9.0 +/- 2.1 vs. 9.2 +/- 2.2; p = .51) did not differ in bivariate or multivariate analyses. In group C, Bili was (11.3 +/- 3.1 vs. 10.1 +/- 3.3; p < .001) and remained the only significant difference in the regression model (RC = 1.19 +/- 0.37; p = .001).

CONCLUSIONS

Bili in LBW infants is significantly higher in males when compared with females. After stratification to birth weight subgroups, significance is retained in the 1500- to 2499-g group after logistic regression analysis. Bili levels in infants <1500 g are influenced more significantly by factors other than gender, such as sepsis and IVH.

Neonatal outcome after trial of labor compared with elective repeat cesarean section

BACKGROUND

Trial of labor after cesarean section has been an important strategy for lowering the rate of cesarean delivery in the United States, but concerns regarding its safety remain. The purpose of this study was to evaluate the outcome of newborns delivered by elective repeat cesarean section compared to delivery following a trial of labor after cesarean.

METHODS

All low-risk mothers with 1 or 2 previous cesareans and no prior vaginal deliveries, who delivered at our institution from December 1994 through July 1995, were identified. Neonatal outcomes were compared between 136 women who delivered by elective repeat cesarean section and 313 women who delivered after a trial of labor. To investigate reasons for differences in outcome between these groups, neonatal outcomes within the trial of labor group were then compared between those mothers who had received epidural analgesia (n = 230) and those who did not (n = 83).

RESULTS

Infants delivered after a trial of labor had increased rates of sepsis evaluation (23.3% vs 12.5%, p = 0.008); antibiotic treatment (11.5% vs 4.4%, p = 0.02); intubation to evaluate for the presence of meconium below the cords (11.5% vs 1.5%, p < 0.001); and mild bruising (8.0% vs 1.5%, p = 0.008). Within the trial of labor group, infants of mothers who received epidural analgesia were more likely to have received diagnostic tests and therapeutic interventions including sepsis evaluation (29.6% vs 6.0%, p = 0.001) and antibiotic treatment (13.9% vs 4.8%, p = 0.03) than within the no-epidural analgesia group.

CONCLUSIONS

Infants born to mothers after a trial of labor are twice as likely to undergo diagnostic tests and therapeutic interventions than infants born after an elective repeat cesarean section, but the increase occurred only in the subgroup of infants whose mothers received epidural analgesia for pain relief during labor. The higher rate of intervention could relate to the well-documented increase in intrapartum fever that occurs with epidural use.

In pregnancies with gestational diabetes mellitus and intensive therapy, perinatal outcome is worse in small-for-gestational-age newborns

OBJECTIVE

This study analyzed the relationship between birth weight and perinatal outcome among women with gestational diabetes mellitus.

STUDY DESIGN

The relationship between perinatal outcome and birth weight was analyzed for 821 pregnancies of women with gestational diabetes mellitus attended in a tertiary hospital and receiving intensive metabolic therapy (normocaloric diet, self-monitoring of blood glucose level and individually tailored insulin regimen when needed). The Mantel-Haenszel test was used to adjust for preterm delivery.

RESULTS

Seven percent of neonates were small for gestational age, 85% were appropriate for gestational age, and 8% were large for gestational age. After adjustment for preterm delivery the rates of adverse fetal outcome, low 1-minute Apgar score, and hypoglycemia were greater among small for gestational age neonates than among appropriate and large for gestational age infants (odds ratios 3.08, 2.51, and 3.17, respectively).

CONCLUSION

Among women with gestational diabetes mellitus who are receiving intensive therapy, perinatal outcome is worse for small for gestational age neonates than for appropriate and large for gestational age neonates.

Breast milk beta-glucuronidase and prolonged jaundice in the neonate

Breast milk samples from mothers of breast-fed, healthy, term newborns with unexplained prolonged jaundice were analyzed for beta-glucuronidase activity. Mean enzyme activity was 75.7 +/- 34.5 modified Sigma units/ml in the breast milk samples ingested by the study group of jaundiced babies (n = 25) and 82.2 +/- 40.1 modified Sigma units/ml in the samples ingested by the control group of non-jaundiced babies (n = 20) (p > 0.05). Enzyme activities at 2, 3 and 4 postnatal weeks were 101.0 +/- 39.9, 66.0 +/- 20.7 and 57.0 +/- 22.4 modified Sigma units/ml in the study group and 87.9 +/- 36.1, 58.5 +/- 15.0 and 88.3 +/- 49.1 modified Sigma units/ml in the controls. The differences were not statistically significant (p > 0.05). We conclude that breast milk beta-glucuronidase activity may be a contributory factor, in the presence of other variables, in hyperbilirubinemia but it is neither the main nor the only cause of prolonged jaundice in neonates.

'Idiopathic' jaundice in Sardinian full-term newborn infants: a multivariate study

'Idiopathic' hyperbilirubinaemia in the first 4 days of life was studied in 431 unselected healthy full-term (gestational age > or = 37 weeks) singleton Sardinian infants with birthweight > or = 2500 g. All infants were free from malformations or any disease requiring treatment other than jaundice, they were ABO and Rh compatible with their mothers and were not G6PD deficient. The serum bilirubin level was > 11.9 mg/dl (204 mumol/l) and > 14.9 mg/dl (256 mumol/l) in 37.1% and 15.3% of the study subjects. The vast majority of the infants (94%) were breast fed; no difference in the incidence of jaundice was found between breast-fed and bottle-fed infants. A logistic regression analysis indicated that high alpha-fetoprotein concentrations in cord blood, history of neonatal jaundice in previous full-term siblings, delayed first meconium passage and weight loss were associated with jaundice, defined as a serum bilirubin level > 11.9 mg/dl. These results suggest that the high rate of neonatal hyperbilirubinaemia in Sardinia is mostly related to constitutional and possibly hereditary factors.

Investigation of Newborn Hyperbilirubinemia: Helping family physicians indentify newborns at risk

The trend to early neonatal discharge underscores the need to detect and manage neonatal hyperbilirubinemia. In a retrospective study, 84 charts from newborns were audited for clinical hyperbilirubinemia. Jaundice was recorded for 29% of the newborns, 92% of cases appearing after the second day. Audits of additional 257 charts indicated that neonates delivered by cesarean section were twice as likely to develop jaundice.

Enzyme variability and neonatal jaundice. The role of adenosine deaminase and acid phosphatase

A sample of children treated by phototherapy during the neonatal period has been studied in the population of Penne (South Eastern Italy) in order to confirm the association previously reported in newborns from the population of Rome between neonatal jaundice and phenotypes of adenosine deaminase (ADA) and acid phosphatase (ACP1). The present data confirm that the incidence of clinically relevant jaundice is much greater in newborns of phenotype ACP1 BA carrying ADA2 allele than in other infants. Since ACP1 probably acts as flavin mononucleotide phosphatase and is modulated by purine nucleotides, it is likely that enzymes of purine nucleotide metabolism (including ADA), ACP1 and flavoenzymes (including gluthatione reductase and enzymes of Krebs cycle), may represent a polygenic complex influencing bilirubin levels in the first few days of life.

Randomised comparison of early versus late induction of labour in post-term pregnancy

In a prospective randomised study of mothers referred for prolonged pregnancy (around the 42nd week) 214 (group 1) were submitted to attempted induction of labour and 195 (group 2) assigned to continue for a further week without intervention. Strict selection criteria were used for the certainty of term. Mothers in group 2 were given regular non-stress tests to ensure fetal wellbeing, as were those in group 1 in whom induction failed. In group 1, 48 (23%) out of 210 first attempted inductions failed. In group 2, 135 (69%) of the births started spontaneously as compared with 38 (18%) in group 1. The mean duration of labour was 7.5 hours in each group. There was no significant difference in incidence of operative delivery, use of analgesics, or signs of perinatal asphyxia. Significantly more children in group 1 needed phototherapy for hyperbilirubinaemia. There was a clustering of births in the late afternoon and evening, which was most pronounced in group 1. A policy of vigilant non-intervention up to the 44th completed week of pregnancy does not appear to jeopardize mother or fetus.

Risk factors and sib correlation in physiological neonatal jaundice

The effect of a number of explanatory variables on the degree of physiological jaundice in mature infants was evaluated by multiple regression analysis. The sampling was designed so that comparisons could be made between siblings. We found an effect of gestational age, gender, infant nutrition, ABO incompatibility and induction of labour. Taking these factors into account we still found a highly significant correlation between the peak bilirubin levels of siblings. Whether this correlation is genetically or environmentally determined is not clear.

Neonatal jaundice: its prevalence in Chinese babies and associating factors

A prospective study of 1238 full-term Chinese newborn infants was conducted to determine the incidence of neonatal jaundice and associated factors. A significantly more severe degree of hyperbilirubinaemia was present in infants whose ABO blood group was incompatible with that of their mothers and those who were deficient in the enzyme glucose-6-phosphate dehydrogenase (G6PD). Among the remainder, clinical jaundice was present in 87% and 23.9% had a peak serum bilirubin (SB) concentration greater than 204 mumol/l. Factors that were found to have an association with a higher peak SB concentration included: male infants; elder siblings who had a history of neonatal jaundice; and breast-fed infants with or without supplementation with formula feed. Factors that were found to have no significant association with the peak SB concentration were: gestational age; birthweight; the mode of delivery of the infants; maternal consumption of Chinese herbs and syntocinon induction or augmentation of labour.

Perinatal events and neonatal morbidity: an analysis of 5380 cases

The associations between perinatal events and neonatal morbidity were examined in a regional population of 5 380 newborns weighing 500 g or more. Perinatal mortality was 6.9%, and neonatal mortality was 3.0%. The low birth weight (less than 2500 g) rate was 3.8%. The incidence of prematurity (gestational age less than 37 weeks) was 6.6%. Respiratory distress syndrome was found in 0.9%, nonhaemolytic hyperbilirubinaemia in 16.5%, hypoglycaemia in 0.5%, septic infection in 0.8%, asphyxia in 4.0%, intracerebral haemorrhage in 0.3%, and cerebral symptoms in 0.7%. Maternal toxaemia, multiple pregnancy and maternal short stature were associated with spontaneous prematurity and a birthweight below the 10th percentile. Prematurity was associated with respiratory distress syndrome, hyperbilirubinaemia, hypoglycaemia, infection, low Apgar scores, asphyxia and intracerebral haemorrhage. Placental complications were associated with spontaneous prematurity, low Apgar scores and asphyxia. Premature rupture of the membranes was associated with spontaneous prematurity, infection, low Apgar scores and asphyxia.

Neonatal jaundice and fatty acid composition of the maternal diet

The role of serum fatty acid composition in neonatal jaundice was studied by comparing the incidence of jaundice among 332 newborn infants receiving breast milk from mothers on a diet with either a low (0.1, n = 145) or a high (1.5, n = 187) polyunsaturated to saturated fatty acid (P/S) ratio. The diet was started immediately after delivery. The composition of fatty acids in the breast milk and sera of the mothers and in the sera of the newborns was evaluated from a random sample of 15 mother-newborn pairs on the control diet (low P/S ratio) and 19 pairs on the experimental diet. Five days after delivery the relative amounts of fatty acids, especially that of linoleate, in the sera of the mothers differed significantly depending on the diet. Differences were also observed in breast milk samples taken three, four or five days after delivery and in the sera of the newborns sampled at the age of four or five days. Nine of the 145 newborn infants (6.2%) in the control group had to be treated with light therapy compared with 12 out of 187 (6.4%) of the newborn infants in the experimental group (high P/S ratio). Serum bilirubin concentrations were 142.5 mumol/l (SD 65.8) and 140.7 mumol/l (SD 73.5) in the experimental and control groups, respectively, at the age of five days. It appears that the changes in the composition of serum fatty acids reached in this study had no effect on the neonatal jaundice.

Serum bilirubin levels in Melanesian neonates

The pattern of early neonatal serum bilirubin levels in a population of normal fullterm healthy Melanesian babies was determined. The mean (and standard deviation) of cord blood serum bilirubin from 98 babies was 1.2 (1.4) mg/dl (20.5 (23.9) mumol/l). Between 24 and 60 h of age the mean serum bilirubin from 99 babies was 8 (3.5) mg/dl (136.8 (59.85) mumol/l). Seventeen babies excluded from the main study group because of factors known to predispose to neonatal jaundice had a mean serum bilirubin of 10.7 mg/dl (183 mumol/l). In the early neonatal period, Melanesian babies have a mean serum bilirubin level higher than that reported for Caucasian but lower than that reported for Asian babies. Genetic factors are the most likely explanation for these differences.

Neonatal jaundice after labour induced or stimulated by prostaglandin E2 or oxytocin

In a prospective study of neonatal jaundice 739 infants, delivered vaginally, in the vertex presentation, and without major complications, were examined. Labour was induced or stimulated after random allocation of the mothers to one of three oxytocics (prostaglandin E2 orally, oxytocin intravenously, or demoxytocin buccally). Oxytocics were unnecessary after primary amniotomy in 91 women. A linear logistic statistical analysis showed that gestational age has a highly significant influence on the risk of jaundice (defined by maximum serum level of bilirubin greater than or equal to 205 mumol/l). An apparent influence of birthweight could be explained by the correlation between birthweight and gestational age. The influence of the three oxytocic agents was not significant, although they may have had a slight effect; however, any such effect could be a consequence of the infants of mothers given oxytocics being less mature than those whom mothers did not receive oxytocics. The duration of labour and the mother's age also had no effect on risk of jaundice. Thus, neonatal jaundice after induced and stimulated labour seems to be primarily associated with fetal maturity; the pharmacological side-effect, if any, of oxytocics is of no importance.

Prophylaxis of neonatal jaundice with maternal antipyrine treatment

A randomised controlled trial of antipyrine (phenazone) in the prophylaxis of neonatal jaundice was completed in 48 women. Treatment of mothers from the 38th week of pregnancy reduced neonatal plasma-bilirubin concentrations on the 4th day after birth by an average of 44%. Prophylaxis of neonatal jaundice merits a wider trial.

The effect of oxytocin in induced labour on neonatal jaundice

A prospective study in 180 mothers and babies examined the effects of oxytocin in induced labour on plasma bilirubin levels in cord blood, as well as on the incidence of neonatal jaundice. Raised plasma bilirubin levels in cord blood, probably enhanced by breakdown of fetal red cells, appeared to be a dose dependent effect of oxytocin. Commensurate with this was the finding that a larger proportion of babies in the induced group manifested a greater severity of jaundice.

Factors affecting neonatal jaundice

Plasma bilirubin was estimated on 690 term infants on about the 6th day of life. Perinatal factors were recorded and the results analysed. Hyperbilirubinaemia was defined as a level greater than 205 micromol/1 (12 mg/100 ml) and this was present in 20% of cases. Three factors--epidural analgesia, breast feeding, and poor weight recovery--showed highly significant associations with jaundice. The relative importance of these is discussed and compared with recent reports. Induction of labour, for reasons other than postmaturity, and a gestational age less than 39 weeks showed a slightly increased incidence of jaundice. There was no correlation with other factors tested including oxytocic drug administration. Despite the high incidence (20%) of hyperbilirubinaemia, only 2.5% infants needed treatment and none required exchange transfusion. Radical changes in obstetric management or infant feeding are not indicated.