Influence of simultaneous low amniotomy and oxytocin infusion and other maternal factors on neonatal jaundice: a prospective study

Risk of hyperbilirubinemia in breast-fed infants

OBJECTIVE

To investigate the risk factors for hyperbilirubinemia in infants who are exclusively breast-fed.

STUDY DESIGN

A prospective study was conducted to investigate the effects of birth body weight, sex, mode of delivery, glucose-6-phosphate dehydrogenase (G6PD) deficiency, variant UDP-glucuronosyltransferase 1A1 (UGT1A1) gene, and hepatic solute carrier organic anion transporter 1B1 (SLCO1B1) gene on hyperbilirubinemia in neonates who were breast-fed. Hyperbilirubinemia was diagnosed when a full term neonate had a bilirubin level ≧15.0 mg/dL (256.5 μM) in serum at 3 days old. The polymerase chain reaction-restriction fragment length polymorphism method was used as a means of detecting the known variant sites in the UGT1A1 and SLCO1B1 gene.

RESULTS

Of 252 infants born at term who were exclusively breast-fed, 59 (23.4%) had hyperbilirubinemia. The significant risk factors were a variant nucleotide 211 in UGT1A1 (2.48; 95% CI, 1.29 to 4.76; P = .006), G6PD deficiency (12.24; 95% CI, 1.08 to 138.62; P < .05), and vaginal delivery (3.55; 95% CI, 1.64 to 7.66; P < .001).

CONCLUSION

Breast-fed neonates who are 211 variants in the UGT1A1, G6PD deficiency, and vaginal delivery are at high-risk for hyperbilirubinemia.

Transcutaneous bilirubin levels in the first 96 hours in a normal newborn population of > or = 35 weeks' gestation

OBJECTIVE

To obtain transcutaneous bilirubin (TcB) measurements, at 6-hour intervals, in the first 96 hours after birth in a normal newborn population (gestational age: > or =35 weeks).

METHODS

We performed 9397 TcB measurements on 3984 healthy newborn infants (gestational age: > or =35 weeks) from 6 to 96 hours of age. All measurements were performed in the well-infant nursery with a Draeger Air-Shields transcutaneous jaundice meter (model JM-103), within 2 hours of the designated time.

RESULTS

There was a distinct pattern to the velocity of the increase in TcB levels over different time periods. TcB levels increased in a linear manner most rapidly in the first 6 to 18 hours and then less rapidly from 18 to 42 hours, followed by a much slower increase until peak levels occurred. Decreasing gestational age was associated significantly with higher TcB levels.

CONCLUSIONS

We provide data on neonatal bilirubinemia, based on TcB levels determined in a large, predominately white and breastfed, North American population. Infants who require closer evaluation and observation initially are those whose bilirubin levels are > or =95th percentile, ie, increasing more rapidly than 0.22 mg/dL per hour in the first 24 hours, 0.15 mg/dL per hour between 24 and 48 hours, and 0.06 mg/dL per hour after 48 hours. These data should be useful for detecting aberrant trends, identifying infants who need additional evaluation, and planning appropriate follow-up for jaundiced newborns.

Identifying newborns at risk of significant hyperbilirubinaemia: a comparison of two recommended approaches

AIMS

To compare the predictive performance of clinical risk factor assessment and pre-discharge bilirubin measurement as screening tools for identifying infants at risk of developing significant neonatal hyperbilirubinaemia (post-discharge total serum bilirubin (TSB) >95th centile).

METHODS

Retrospective cohort study of term and near term infants born in an urban community teaching hospital in Pennsylvania (1993-97). A clinical risk factor scoring system was developed and its predictive performance compared to a pre-discharge TSB expressed as a risk zone on a bilirubin nomogram. Main outcome measures were prediction model discrimination, range of predicted probabilities, and sensitivity, specificity, positive and negative predictive values, and likelihood ratios for various positivity criteria.

RESULTS

The clinical risk factor scoring system developed included birth weight, gestational age <38 weeks, oxytocin use during delivery, vacuum extraction, breast feeding, and combination breast and bottle feeding. The pre-discharge bilirubin risk zone had better discrimination (c = 0.83; 95% CI 0.80 to 0.86) than the clinical risk factor score (c = 0.71; 95% CI 0.66 to 0.76) and predicted risk of significant hyperbilirubinaemia as high as 59% compared with a maximum of 44% for the clinical risk factor score. Neither the risk score nor the pre-discharge TSB risk zone predicted the outcome with > or =0.98 sensitivity without significantly compromising specificity (0.13 and 0.21, respectively). Multi-level clinical risk factor scores and TSB risk zones produced likelihood ratios of 0.15-3.25 and 0.05-9.43, respectively.

CONCLUSIONS

The pre-discharge bilirubin expressed as a risk zone on an hour specific bilirubin nomogram is more accurate and generates wider risk stratification than a clinical risk factor score.

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.

Jaundice in full term healthy neonates--a population study

A geographically based population of 498 full term, appropriate for gestational age, healthy, singleton neonates was used to study the effect of obstetric and nursery practices on the occurrence of neonatal jaundice. At 3-4 days 56% of babies became visibly jaundiced (plasma bilirubin (PB) greater than 100 mumol/l) and 10% were hyperbilirubinaemic (PB greater than 200 mumol/l). Less mature babies, those slow to pass meconium and those who had lost weight at 4 and 7 days were more likely to be jaundiced. Obstetric practices, drugs given during labour, mother's or baby's blood group, natural illumination, plethora, extravasated blood or mode of feeding were found to have no effect. No benefit from giving supplementary milk or dextrose to breast fed babies was discovered. At 6-7 days at least 9% of babies, all but one of whom were breast fed, were visibly jaundiced. The frequency of prolonged jaundice (breast milk jaundice) was 3.8% of breast fed babies at 3 weeks and zero by 7 weeks. The proportion of babies receiving phototherapy was 2.2%.

Birth weight, and use of oxytocin and analgesic agents in labour in relation to neonatal jaundice

A prospective study of 1977 babies, delivered in two district hospitals in the Northern Tablelands area of New South Wales, revealed a highly significant relationship between neonatal jaundice and birth weight in all cases of neonatal jaundice (P = 0.0001). The use of oxytocin was associated with a significant increase in the incidence of jaundice (all cases, P = 0.003; severely jaundiced babies, P = 0.05). This effect was related to the total dose of oxytocin used (P = 0.003 for all cases; P = 0.056 for severely jaundiced babies), but not to its rate of administration. No significant difference was apparent whether oxytocin was administered to initiate or to accelerate labour. The suggestion that oxytocin use is associated with delivery of immature babies is refuted. The use of analgesic agents during labour was not associated with an increased incidence of neonatal jaundice.

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.

Effect of segmental epidural block on the course of labour and the condition of the infant during the neonatal period

Epidural block for vaginal delivery was given to 242 women during a 6-month period. Of these, 178 with a spontaneous start of labour and vaginal delivery were studied with respect to the effect of epidural block with bupivacaine-adrenaline on the course of labour and the condition of the infant in women with normal uterine activity and women with primary uterine inertia treated with oxytocin infusion. On average, the 178 women had already had a longer course of labour before the block was applied than women in control groups. The block per se had only a slight effect on the first stage of labour, but the effect on the second stage was more obvious, leading to outlet extraction in 50% of the primiparous women, compared to 12% of the controls. Transitory asphyxia at birth was observed in 4.5% of the infants of mothers with epidural block, but after 5 min, only 1% had an Apgar score of less than 7. Infants of mothers with epidural block were more often placed under observation or treated in the neonatal ward than infants in control groups.

Pathogenesis of oxytocin-induced neonatal hyperbilirubinaemia

100 term (gestation at least 37 weeks), vertex presenting, vaginally delivered, and fetomaternal blood-group-compatible neonates were studied to evaluate the pathogenesis of neonatal hyperbilirubinaemia induced by oxytocin. 50 infants were born after oxytocin infusion for augmentation of labour and the other 50 were delivered spontaneously. The babies born after oxytocin induction of labour attained significantly higher serum bilirubin levels at age 72 +/- 12 hours than the controls. Infants born after oxytocin showed significant hyponatraemia, hypo-osmolality, and enhanced osmotic fragility of erythrocytes at birth. These biochemical and physiological alterations can be explained by the antidiuretic effects of oxytocin and concomitant administration of large quantities of electrolyte-free dextrose solutions used to administer it. Our observations suggest that cord serum sodium and/or osmolality should be estimated and infants with serum sodium less than 125 mmol/l and/or osmolality less than 260 mmol/kg should be considered for prophylactic administration of phenobarbitone.

Infant outcome following labor induction

A matched control study was undertaken in which 156 children were examined between ages 23 and 62 months after births associated with spontaneous labor, oxytocin-induced labor, or prostaglandin E2 (PGE2)--induced labor. Physical development was not adversely affected by labor induction based on height and weight percentiles. The frequency of neurologic or developmental abnormalities not attributable to postdelivery events was the same overall in induced and spontaneous labors (19.2 per 1,000), but those abnormalities occurring after labor induction all followed use of oxytocin. None followed PGE2 despite case-selection criteria which specifically chose PGE2 cases from among those with documented adverse drug-related reactions.

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.

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.

Factors influencing the incidence of neonatal jaundice

A retrospective study of 12 461 single births confirmed an association between maternal oxytocin infusion and neonatal jaundice. The effect of oxytocin on jaundice was independent of gestational age at birth, sex, race, epidural anaesthesia, method of delivery, and birth weight, each of which was significantly associated with neonatal jaundice. The effect of oxytocin was, however, small, producing a calculated mean increase in peak plasma bilirubin concentration of 8.6 mumol/1 (0.5 mg/100 ml); this excess was independent of sex and less than the effect of the baby being born one week earlier.