Neonatal jaundice and maternal oxytocin infusion

Natural history and predictive risk factors of prolonged unconjugated jaundice in the newborn

BACKGROUND

This study aimed to investigate the natural course and risk factors for prolonged unconjugated jaundice (PUJ) in neonates.

METHODS

This was a prospective descriptive study conducted in a tertiary care referral hospital of Northern India. The study included neonates who presented with clinical jaundice beyond 14 days of age. A detailed history, clinical examination and investigations were performed in all. All were followed till the normalization of clinical jaundice or up to 8 weeks of age, whichever was earlier. The key outcome measure was time to normalization of PUJ. Predictive risk factors for PUJ were analyzed by comparing with matched controls. Regression analysis was done for independent predictive risk factors of PUJ.

RESULTS

A total of 71 infants presented with prolonged jaundice (PJ). Out of these, 66 infants (93%) had PUJ. Glucose-6-phosphate dehydrogenase (G6PD) deficiency was the most commonly identified association of PUJ (24%). The median duration of jaundice in infants with PUJ was 5 weeks (range: 5-8). PJ in siblings (OR 2.9 [1.1-7.6]), oxytocin use during labor (OR 3.4 [1.1-10.4]) and G6PD deficiency (OR 4.0 [1.1-14.1]) were independent predictors of PUJ.

CONCLUSIONS

Irrespective of the etiology, by 8 weeks, PUJ disappeared in all infants. G6PD deficiency was the most common association of PUJ. A history of PJ in siblings, use of oxytocin during labor and G6PD deficiency were independent predictors for PUJ.

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.

The endocrinology of parturition in the human

Current evidence suggests that oestrogens, progesterone, relaxin, the prostaglandins, and oxytocin are all hormones concerned to a major degree with the onset and maintenance of parturition. Oestrogens, relaxin, and the prostaglandins are particularly involved with cervical ripening, while prostaglandins, progesterone and oxytocin are more involved in regulating myometrial contractility. Catecholamines may also have some regulatory function in relation to uterine contractions. Progesterone dominance during pregnancy is associated with a firm closed cervix, few myometrial gap junctions, low calcium levels in the cells, and a quiescent myometrium. At term, a change in the oestrogen/progesterone balance favours cervical ripening and increased uterine activity. Of particular importance at the level of the muscle cell are changes in the number of oxytocin receptors; a complex interaction between cAMP and phosphoinositide metabolism governs the intracellular level of calcium, thus regulating contractile activity.

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%.

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.

Vacuum extraction and neonatal jaundice

Various fetal scalp lesions are related to the use of the vacuum extractor. Blood sequestered in these lesions could result in an increased bilirubin load on the functionally limited neonatal liver, leading to the development of hyperbilirubinemia. In the present study bilirubin levels of vacuum extracted neonates were compared with those of non-instrumentally delivered babies during the first 72 hours of life. Sixty-nine vacuum extracted neonates had higher bilirubin levels than 56 non-instrumentally delivered babies at 24 (114 mumol/l vs. 96 mumol/l), 48 (163 vs. 141) and 72 (194 vs. 144) hours of age. The p values were 0.05, less than 0.025 and less than 0.001 respectively. This trend was apparent in both oxytocin induced and non-induced deliveries and whether or not phototherapy cases were included in the analysis. The incidence of hyperbilirubinemia requiring phototherapy was higher after vacuum extraction than after non instrumental delivery (27.5% vs. 12.5%; p less than 0.04). Analysis of our results unexpectedly indicated that oxytocin induction was generally associated with an attenuation of bilirubin levels after both vacuum extraction and spontaneous delivery. The clinician attending newborn babies should be aware of the higher incidence of neonatal hyperbilirubinemia associated with vacuum extraction.

Promotion of breast feeding: effect on neonates of change of feeding routine at a maternity unit

The effect on the health of neonates of a change in neonatal routine care, including general rooming-in, breast feeding on demand and avoidance of supplementary bottle feeding was studied in conjunction to a breast feeding campaign at a maternity unit. There was an accentuated weight loss in the neonatal period during ad libitum breast feeding. The mean serum bilirubin of clinically jaundiced infants was slightly higher on a 4-hourly feeding schedule with supplementary bottles than on the new regimen. There was a similar high (32-33%) incidence of bilirubin levels greater than 205 mumol/l (12 mg/100 ml) in both groups. The incidence of spontaneous hypoglycaemia did not differ in the two groups. The new feeding regimen was thus considered safe. Infants at risk for hypoglycaemia were given supplementary bottles and were excluded from the study.

Pathogenesis of neonatal hyperbilirubinaemia after induction of labour with oxytocin

To determine the pathogenesis of neonatal hyperbilirubinaemia after oxytocin-induced labour venous cord blood from 95 healthy newborn infants was examined. Of these, 15 were delivered by elective caesarean section, 40 after spontaneous labour, and 40 after oxytocin-induced labour. There was no significant difference in any haematological or biochemical variable between the first two groups. Infants born after oxytocin-induced labour, however, showed clear evidence of increased haemolysis associated with significantly decreased erythrocyte deformability (P less than 0.001). In-vitro studies showed a time- and dose-related reduction in erythrocyte deformability in response to oxytocin. The findings suggest that the vasopressin-like action of oxytocin causes osmotic swelling of erythrocytes leading to decreased deformability and hence more rapid destruction with resultant hyperbilirubinaemia in the neonate.

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.

Neonatal serum bilirubin levels in spontaneous and induced labour

An investigation was made into the onset and severity of neonatal jaundice in 114 patients following spontaneous labour and labour induced by (a) amniotomy, (b) amniotomy and simultaenous infusion of oxytocin, (c) amniotomy and simultaneous administration of oral prostaglandin E2 (PGE2). No significant difference in serum bilirubin levels in the first five days of life was found in the four groups.

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.

A review of the significance of gestational diabetes

One hundred and ninety-six pregnancies complicated by gestational diabetes in a referred private practice over an 18-year period have been reviewed. Initially they were managed as true diabetics and the pregnancies terminated before the 38th week. More recently, pregnancies have been managed on an outpatient basis and allowed to proceed to term, with a higher percentage of vaginal deliveries and no increase in perinatal mortality or morbidity. A high incidence of neonatal jaundice was noted, but no explanation emerged. Differences between true diabetes and gestational diabetes, with particular reference to perinatal mortality are discussed and the good prognosis for the gestational form emphasised. Follow-up suggests that a continuation of the rapport established between physician, obstetrician and patient during pregnancy may be important in delaying or preventing the subsequent onset of diabetes.

A multifactorial survey of neonatal juandice

Concern about a neonatal jaundice rate of 8-6 per cent prompted a retrospective survey of 981 full term infants. There was a highly significant association between increased oxytocin dosage and neonatal jaundice in induced labours. A significant association was also demonstrated between neonatal jaundice and both breast-feeding and minor infections. No association was demonstrated between neonatal jaundice and the method of delivery of birth weight. The results of the survey suggest that while oxytocin in high doses should be used with caution, the benefits obtained from the drug outweigh the risk of hyperbilirubinaemia which it may cause.

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

In a prospective study of 196 consecutive single births a significant increase in serum bilirubin concentrations was found in infants born after low amniotomy induction and oxytocin infusion compared with those born spontaneously. This relationship was not dose-dependent and may have been associated with artificial interruption of pregnancy rather than the oxytocin itself. Infants delivered after spontaneous labour accelerated by oxytocin showed no such increase. The hormonal surge at the spontaneous onset of labour may affect fetal enzyme induction, but other factors, such as methods of infant feeding and oral contraceptive use, were found not to be significant.

Relation of umbilical vein cortisol to neonatal bilirubin concentrations

Umbilical vein cortisol levels were assayed following spontaneous labour in 30 patients. Serum bilirubin was measured in the infants born at three days after delivery. No correlation was demonstrated between third day bilirubin concentration and the cord blood cortisol. The implications of this finding are discussed.

Neonatal jaundice--a comparison between intravenous oxytocin and oral prostaglandin E2

The total serum bilirubin levels at two and occasionally five days after birth were studied in 162 infants whose mothers received either intravenous oxytocin or oral Prostaglandin te2 during labour, and the results were compared with those obtained in forty-two control patients. Following labour of spontaneous onset, whether the mother received intravenous oxytocin or oral Prostaglandin E2, neonatal total serum bilirubin levels were not different from those in controls. After induction by amniotomy and an active agent, higher mean total serum bilirubin levels were found in infants whose mothers received intravenous oxytocin than in those given oral prostaglandin E2; a significant rise in the total serum bilirubin level appeared to occur when mothers received a total of more than 12,000 milliunits of oxytocin or more than 4,000 milliunits per kg birthweight of the infant.

Neonatal jaundice in association with oxytocin stimulation of labour and operative delivery

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Factors affecting the increasing incidence of severe non-haemolytic neonatal jaundice

Neonatal hyperbilirubinaemia is increasing in frequency. In view of conflicting evidence about the possible causes, retrospective analyses have been carried out among babies born during six months of 1974. Preliminary analysis confirmed the over-riding importance of preterm birth (before 37 weeks), but only one of 17 such cases could be attributed to ill-judged artificial induction of labor. For the main analysis, the incidence of eight possibly relevant antecedent factors was compared in 46 cases of hyperbilirubinaemia (unconjugated bilirubin more than 15 mg per 100 ml in term babies and more than 13 mg per 100 ml in some preterm babies) and in 92 controls matched for sex and gestational age. Induction of labour by "primary" oxytocin infusion and artificial rupture of the membranes was very significantly more common in the index cases (p less than 0-01), but there was no difference in the incidence of "secondary" oxytocin, used to accelerate spontaneous labour. Evidence of uterin unresponsiveness suggests that the natural onset of labour was being anticipated by at least some days in many of the index cases and this could prevent the natural "priming" of the fetal enzyme systems. An excess of epidural analgesia in the mothers of the index cases was probably due to its association with the need for pain relief during "primary" oxytocin infusions. The higher incidence of postnatal weight loss in the index cases presumably contributed to the hyperbilirubinaemia.

Neonatal jaundice and glucose-6-phosphate dehydrogenase deficiency in Papua New Guinea

Of 50 jaundiced neonatal patients studied at the Port Moresby General Hospital, 11 (22%) were found to be glucose-6-phosphate dehydrogenase-deficient. No apparent exogenous precipitating causes for the jaundice were noted. Serum bilirubin levels exceeded 20 mg/100 ml in seven of these glucose-6-phosphate dehydrogenase-deficient infants, and exchange transfusions were required for three subjects. Glucose-6-phosphate dehydrogenase deficiency must be considered in the differential diagnosis of neonatal jaundice in Papua New Guinea.

Neonatal hyperbilirubinaemia following the use of oxytocin in labour

A prospective study of 1353 labours and the relevant newborn failed to reveal any significant difference between the incidence of neonatal hyperbilirubinaemia (defined as a level of 12 mg. or more per 100 ml.) following spontaneous labour, and after labour induced or accelerated by oxytocin. The incidence of unexplained neonatal hyperbilirubinaemia after spontaneous labour was 6-3 per cent. Following induced labour however there was a highly significant (P less than 0-001) association between the mean total dose of oxytocin used for induction and the incidence of neonatal hyperbilirubinaemia. The proportion of babies who developed hyperbilirubinaemia increased in direct relation to the total dose of oxytocin used for the induction. In this series the incidence of hyperbilirubinaemia increased sharply when the total dose of oxytocin exceeded 20 units as it did hyperbilirubinaemia and birthweight, or duration of spontaneous labour. When labour was induced, however, the proportion on newborn babies with hyperbilirubinaemia increased with the duration of labour. The significance of these findings is discussed.