Pathogenesis of neonatal hyperbilirubinaemia after induction of labour with oxytocin

The Effects of Intrapartum Administration of Synthetic Oxytocin on Breastfeeding in the First 9 Months Postpartum: A Longitudinal Prospective Study

Background and Objective: Synthetic oxytocin (synOT) is a widely used drug to induce or accelerate labor and to prevent postpartum hemorrhage. Although some studies indicate there are associations between intrapartum synOT and impaired breastfeeding initiation or earlier cessation, the long-term effects of synOT on breastfeeding are largely understudied. The aim of this study was to examine the effects of synOT on breastfeeding status during the first 9 months postpartum. Materials and Methods: The women were recruited from five maternity hospitals during prenatal medical checkups or postpartum hospital stay. They reported their breastfeeding status on discharge from maternity hospital (mean 4.54 days postpartum) (N = 439), at 6 weeks (N = 439), and at 9 months postpartum (N = 274). The data related to synOT administration were extracted from the medical records. Results: In the analysis adjusted for maternal age, parity, educational level, marital status, child's sex, delivery mode, and labor analgesia/anesthesia, intrapartum administration of synOT predicted a lower probability of exclusive breastfeeding on discharge from maternity hospital (odds ratio = 0.37; p = 0.006), but we observed no effect on breastfeeding status at 6 weeks or 9 months postpartum. Conclusion: Our results suggest that adverse effects of synOT on breastfeeding do not persist beyond the first postpartum days.

Factors associated with extreme hyperbilirubinaemia in neonates at the University Hospital of the West Indies

AIM

To determine factors associated with extreme hyperbilirubinaemia in neonates at the University Hospital of the West Indies.

METHODS

A retrospective review of all neonates with hyperbilirubinaemia requiring medical intervention at the University Hospital of the West Indies between 1 January 2006 and 30 June 2007 was performed. Factors associated with extreme hyperbilirubinaemia were determined using multiple logistic regression models.

RESULTS

A total of 170 neonates fulfilled the inclusion criteria for the study and 15 (9%) of them had extreme hyperbilirubinaemia. The majority (97, 57%) were term infants and 103 (61%) were male. Exclusively breastfed neonates were more likely to have extreme hyperbilirubinaemia (OR 2.6, 95% CI 0.01-0.6). Neonates whose mothers received oxytocin during labour (OR 2.7, 95% CI 0.02-0.3) and those who were G6PD-deficient (OR 2.6, 95% CI 0.01-0.5) were more likely to have extreme hyperbilurubinaemia.

CONCLUSION

Exclusive breastfeeding, oxytocin use in the mother during labour and G6PD deficiency in the infant were found to be factors associated with extreme hyperbilirubinaemia.

Fluid supplementation in hyperbilirubinemia

OBJECTIVE

To analyze the factors responsible for failure of fluid supplementation in full-term neonates with severe non-hemolytic hyperbilirubinemia.

METHODS

The data from two previous randomized controlled trials was used in this study. Full-term (≥37 wks) neonates with severe hyperbilirubinemia (serum total bilirubin 18-25 mg/dL), who received intravenous fluid supplementation in addition to phototherapy were included. Intravenous fluid supplementation was given for 8 h. Those neonates, whose serum bilirubin levels increased by 2 mg/dL or crossed 22 mg/dL, underwent exchange transfusion. The authors compared baseline serum bilirubin, sodium, and osmolality and their changes during study period in neonates who required exchange transfusion (Non-responders) with those who didn't (Responders).

RESULTS

The data of 121 neonates was analyzed (non-responders = 17, responders = 104). Both the groups had similar weight loss since birth, baseline serum sodium and osmolality. Mean baseline serum bilirubin [22.5 (1.7) vs 21.6 (1.6) mg/dL, p = 0.04] and cesarean/ instrumental delivery (27.6% vs 20.2%, p = 0.02) were significantly higher in non-responders. With fluid supplementation, serum sodium and osmolality changed similarly in both the groups over 8 h. On multiple regression analysis, only cesarean/instrumental delivery [OR 3.9 (95% CI-1.2, 13.4)] retained independent significance.

CONCLUSIONS

Fluid supplementation for severe non-hemolytic hyperbilirubinemia is less likely to be successful in neonates born by cesarean/instrumental delivery as compared to normal vaginal delivery.

The effect of oxytocin infusion and misoprostol on neonatal bilirubin levels

PURPOSE

To investigate the association of neonatal bilirubin levels with oxytocin and misoprostol use for labour induction.

METHODS

A total of 100 neonates were included in the study. The first group consisted of 50 healthy babies of women who had received oxytocin infusion and the second group consisted of 50 healthy babies of women who had received 25 μg misoprostol every 4 h placed in the posterior fornix for labour induction. Bilirubin and haematocrit levels were measured in all on days 1 and 4 of the neonatal period.

RESULTS

The levels of bilirubin in the oxytocin group were significantly higher than those in the misoprostol group on day 1 [4.42 ± 0.27 mg/dl versus 3.55 ± 0.28 mg/dl (P = 0.035)] while they were higher also on day 4 but was not significantly so [7.47 ± 0.63 mg/dl versus 6.86 ± 0.65 mg/dl (P = 0.525)]. The mean haematocrit levels on day 1 were 50.62 ± 1.23 and 58.04 ± 1.30 in groups 1 and 2, respectively, with a significant difference between them. The levels were 52.31 ± 1.27 and 58.96 ± 1.14 on day 4 and the difference was again significant. P < 0.05 indicated statistical significance.

CONCLUSIONS

Labour induction with misoprostol and oxytocin does not seem to have harmful effects on bilirubin levels in the neonate.

The effect of oxytocin infusion and misoprostol on neonatal bilirubin levels

PURPOSE

To investigate the association of neonatal bilirubin levels with oxytocin and misoprostol use for labour induction.

METHODS

A total of 100 neonates were included in the study. The first group consisted of 50 healthy babies of women who had received oxytocin infusion, and the second group consisted of 50 healthy babies of women who had received 25 microg misoprostol every 4 h placed in the posterior fornix for labour induction. Bilirubin and haematocrit levels were measured in all on days 1 and 4 of the neonatal period.

RESULTS

The levels of bilirubin in the oxytocin group were significantly higher than those in the misoprostol group on day 1 [4.42 +/- 0.27 vs. 3.55 +/- 0.28 mg/dl (P = 0.035)] while they were higher also on day 4 but not significantly so [7.47 +/- 0.63 vs. 6.86 +/- 0.65 mg/dl (P = 0.525)]. The mean haematocrit levels on day 1 were 50.62 +/- 1.23 and 58.04 +/- 1.30 in groups 1 and 2, respectively, with a significant difference between them. The levels were 52.31 +/- 1.27 and 58.96 +/- 1.14 on day 4 and the difference was again significant. P < 0.05 indicated statistical significance.

CONCLUSIONS

Labour induction with misoprostol and oxytocin does not seem to have harmful effects on bilirubin levels in the neonate.

Could oxytocin administration during labor contribute to autism and related behavioral disorders?--A look at the literature

This literature review summarizes recent potential evidence, most of which is at the molecular/mechanistic level, in support of Hollander's hypothesis that excess oxytocin (OT), possibly through OT administration at birth, could contribute to the development of autistic spectrum disorders and related syndromes by proposed down regulation of the OT receptor (OTR). In this review, recent molecular evidence for OTR internalization by excess OT is related to OT's reported effects on animal social behavior, favoring social bondage, notably in sheep, voles, rats and especially mice. Adding indications for OT's capability of crossing the maternal placenta and OT's possibility of crossing an underdeveloped or stressed infantile blood brain barrier at birth, a causal connection between OT excess and behavioral disorders such as autism can be supported from a molecular perspective. Possible strategies such as a thorough statistical analysis of numerous birth records as well as molecular studies such as radiotracing using labeled OT are proposed to test this hypothesis.

Pulsatile oxytocin for induction of labor: a randomized prospective controlled study

In a prospective randomized study, 20 patients with term pregnancies underwent induction of labor with either continuous or pulsed (every 8 minutes) intravenous oxytocin infusion. There were no significant differences with respect to induction-labor interval, induction-delivery interval, cesarean section rates, need for pain relief and Apgar scores. Sixty percent of patients receiving continuous oxytocin infusion developed uterine hyperstimulation but only 10% receiving pulsed oxytocin did so. However, the difference was not significant. The mean +/- SEM total amount of oxytocin given by continuous infusion was 4237 +/- 1066 mU which was 70% more than by pulsatile infusion (2454 +/- 808 mU). The highest rate of oxytocin infused was significantly lower by pulsatile administration (5.2 +/- 0.8 mU/min) than by continuous infusion (9.2 +/- 1.8 mU/min, p = less than 0.05). Our study demonstrates that pulsed administration of oxytocin every 8 minutes is as effective and safe as continuous intravenous infusion of oxytocin for induction of labor, requires less oxytocin with therefore, a wider margin of safety and is consistent with the pulsatile release of oxytocin during normal labor.

Effect of saline and glucose infusions of oxytocin on neonatal bilirubin levels

OBJECTIVE

To ascertain the effect of isotonic saline and glucose infusions of oxytocin on neonatal bilirubin levels.

METHOD

Eighty-two parturient Nigerian women requiring oxytocin infusion in labor were randomized into two groups receiving 0.9% saline or 5% glucose, respectively. A group of 82 women not requiring oxytocin were recruited for comparison. All had sodium and bilirubin estimations in cord plasma and neonatal bilirubin assay on Day 3.

RESULT

Analysis of variance revealed higher mean cord and neonatal bilirubin levels in the glucose group compared with the other two (P < 0.05). Significant inverse correlation was observed between cord plasma sodium and neonatal bilirubin levels in all groups. Hyperbilirubinemia occurred in 55% of babies in the glucose group compared with 21% and 22% in the saline and control groups, respectively (P < 0.001).

CONCLUSION

The use of isotonic saline rather than 5% glucose solution as vehicle for oxytocin infusion in labor appears to be associated with lower neonatal bilirubin levels.

Massive perinatal hepatic necrosis from maternal oxytocin overdose

Review of clinical records regarding administration of oxytocin may provide clues to the etiology of hepatic infarction in the neonate. The authors present a case in which a large and rapid maternal overdose of oxytocin (17,300 mU over 20 min) during end-stage labor was associated with neonatal death and extensive hepatic infarction. These findings represent novel complications of oxytocin administration.

Induction of labor with pulsatile oxytocin

In a prospective, randomized study, 106 patients underwent induction of labor with either pulsed (every 8 minutes) (n = 50) or continuous (n = 56) intravenous infusion of oxytocin. Maternal characteristics, gestational age at induction, induction-delivery interval, analgesia for labor, cesarean section rates, and newborn characteristics were similar in both groups. The mean +/- SEM total oxytocin administered was significantly less in the pulsed group (3564 +/- 487 mU) than in the continuous group (7684 +/- 844 mU; p less than 0.0001); the average dose of oxytocin administered per minute was significantly lower in the pulsed group (3.9 +/- 0.3 mU/min) than in the continuous group (7.8 +/- 0.4 mU/min; p less than 0.0001); the peak or highest administered dose of oxytocin expressed per minute was also signficantly lower in the pulsed group (9.6 +/- 0.8 mU/min) than in the continuous group (14.1 +/- 0.7 mU/min; p less than 0.0001). These significant differences persisted even when controlled for parity, Bishop's score of the cervix, and number of days induction of labor was carried out. Uterine hyperstimulation occurred infrequently in both groups (3.6% to 4.0%). The pulsed group required a significantly smaller infusion volume (25 +/- 14 ml) than the continuous group (780 +/- 84 ml; p less than 0.0001). Thus pulsatile administration uses significantly less oxytocin and infusion fluid but is as effective and safe as continuous infusion.

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.

Degradation of radiolabelled arginine vasopressin (125I-AVP) by the human placenta perfused in vitro

The capacity of the human placenta to degrade 125I-labelled arginine vasopressin (125I-AVP) was studied in vitro using a dual circuit perfused lobule preparation. Seven placentas were perfused with the perfusate on the maternal side of the lobule containing 125I-AVP at the upper limit of the physiological range. On average, over a 30-min period, 48% of the 125I-AVP appeared to have been metabolized. With one exception, a patient whose labour was augmented with intravenous oxytocin, no 125I-AVP apparently crossed the placental lobule to the fetal circulation. These data indicate that the human placenta has a considerable capacity to degrade AVP.

Oxytocin induction of labour: hyponatraemia and neonatal jaundice

To determine the effects of fluid restriction in induced labour with oxytocin in 5% dextrose solution, maternal venous blood and fetal cord venous blood were examined in 164 mothers in induced labour and 29 mothers with a spontaneous onset of labour. After satisfactory uterine activity was induced either the oxytocin infusion was managed according to routine delivery unit practice (n = 36), or infusion rates were halved (n = 45), or quartered (n = 43), or discontinued (n = 40). Despite fluid restriction during labour the mean sodium concentration in maternal blood or cord blood had fallen to a similar extent in all four induced groups at delivery. Potassium, urea, creatinine, total protein, and albumin in maternal blood or cord blood were affected differently by induced labour as compared with sodium. The fall in sodium concentration in maternal blood was a more consistent reflection of the total volume of fluid received, mean infusion rates and cord blood sodium after infusion rates were quartered or discontinued. The incidence of hyponatraemia was 5% in mothers and 8% in infants. A comparison of hyponatraemic and normonatraemic cord blood showed no significant differences in serum bilirubin levels or red cell counts, but more hyponatraemic infants developed neonatal jaundice. It is suggested that in induced labour fluid restriction alone does not prevent hyponatraemia and neonatal jaundice.

A multicentre prospective randomized controlled trial of induction of labour with an automatic closed-loop feedback controlled oxytocin infusion system

A randomized prospective controlled trial of an automatic feed-back controlled oxytocin infusion system (AIS) for the induction of labour at term was carried out in three hospitals. In primiparae, a four-fold reduction in the total dose of oxytocin infused, for the same induction-delivery interval, was achieved with the AIS compared with standard labour ward protocols relying on midwife control of oxytocin infusion rate. In multiparae, the total dose of oxytocin infused was almost halved when the AIS was used, while the mean duration of labour was increased by 1.6 h to 7.5 h. There were no differences in the mode of delivery or Apgar scores. It is concluded that the AIS is a safe technique for induction of labour. Its use has demonstrated that term labour can be induced efficiently with a mean oxytocin infusion rate between 2.5 and 3 mU/min (max 8.8 mU/min) and a total oxytocin dose infused of less than 5 U.

Intrapartum infusion of aqueous glucose solution, transplacental hyponatraemia and risk of neonatal jaundice

Cord serum sodium levels in three groups of 278 singleton infants, born vaginally at term, were correlated with the incidence of jaundice (serum bilirubin greater than or equal to 85 mumol/1) in the first 3 days of life. Of the 278 infants, 87 were born to mothers who were given infusions of 5% or 10% glucose in water during labour (group I), 90 were born to mothers who received glucose solution as a vehicle for oxytocin (group II), and 101 to mothers who did not receive any intravenous fluid therapy (control group). Jaundice was seen significantly more frequently in groups I (28/87, 32%) and II infants (30/90, 33%) than in the control group (12/101, 12%) (P less than 0.01), but when analysed in relation to cord serum sodium levels, the prevalence of jaundice in the normonatraemic infants (serum sodium greater than or equal to 131 mmol/1) was similar in the three groups. On the other hand, in groups I and II jaundice occurred about 3.5 times more frequently in the hyponatraemic infants [group I (17/32, 53%) and II (20/39, 51%)] than in the normonatraemic infants (P less than 0.01). The difference was not associated with any other perinatal or neonatal characteristic.

Is routine hospitalization needed in antenatal care of twin pregnancy?

A prospective study was carried out to evaluate the significance and efficacy of routine hospital bed rest in prevention of premature birth and pregnancy complications compared to specialized antenatal care at the outpatient clinic of 73 twin pregnancies. The twin pregnancies were screened in health centers by means of symphysis-fundus measurement, and the diagnosis was confirmed by ultrasound examination at the outpatient clinic. On the average the ultrasonic diagnosis was performed during the 23rd gestational week; at this visit the women were divided into two groups with similar follow-up to the end of the 29th gestational week. At this stage one of the groups was hospitalized unless there had been indications for earlier admission. In the hospital group, the mean for gestational week at delivery was 36.7 (+/- 2.4) and in the outpatient group 37.4 (+/- 1.8) respectively (N.S.). There was no difference in the rate of pregnancy complications between the groups too. No statistical differences in the perinatal mortality (7.1% and 1.1% respectively) or birthweights of the newborns were found, either. Present results do not support the idea of using routine hospital bed rest. It could not be proved to have positive effects on the gestational age, birth weight and perinatal mortality of the newborns, nor to the pregnancy complications. In our opinion early diagnosis of twin pregnancy is of decisive importance and specialized ambulatory follow-up could be employed instead of routine bed rest in antenatal care of twin pregnancy.

Induction of labour: a comparison of a single prostaglandin E2 vaginal tablet with amniotomy and intravenous oxytocin

In a randomized controlled study of 100 women of low parity and favourable induction features, induction of labour by means of a single vaginal tablet containing 3 mg of prostaglandin E2 (PGE2) was compared with the conventional method of amniotomy and intravenous oxytocin. Four of the patients (8%) who received the prostaglandin tablet required additional intravenous oxytocin to achieve delivery. The prostaglandin group had a longer mean overall induction-delivery interval but a shorter amniotomy-delivery interval than the oxytocin group. One patient in the PGE2 group and two in the oxytocin group required caesarean section. The PGE2 treated patients expressed a higher level of satisfaction with their method of induction, they required less analgesia, had less blood loss at delivery and their babies had a lower 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.

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.