Severe adverse effects of maternal labetalol in a premature infant

The Risk for Neonatal Hypoglycemia and Bradycardia after Beta-Blocker Use during Pregnancy or Lactation: A Systematic Review and Meta-Analysis

Beta-blockers are often used during pregnancy to treat cardiovascular diseases. The described neonatal side effects of maternal beta-blocker use are hypoglycemia and bradycardia, but the evidence base for these is yet to be evaluated comprehensively. Hence, this systematic review and meta-analysis was performed to evaluate the potential increased risk for hypoglycemia and bradycardia in neonates exposed to beta-blockers in utero or during lactation. A systematic search of English-language human studies was conducted until 21 April 2021. Both observational studies and randomized controlled trials investigating hypoglycemia and/or bradycardia in neonates following beta-blocker exposure during pregnancy and lactation were included. All articles were screened by two authors independently and eligible studies were included. Pair-wise and proportion-based meta-analysis was conducted and the certainty of evidence (CoE) was performed by standard methodologies. Of the 1.043 screened articles, 55 were included in this systematic review. Our meta-analysis showed a probable risk of hypoglycemia (CoE—Moderate) and possible risk of bradycardia (CoE—Low) in neonates upon fetal beta-blocker exposure. Therefore, we suggest the monitoring of glucose levels in exposed neonates until 24 h after birth. Due to the limited clinical implication, monitoring of the heart rate could be considered for 24 h. We call for future studies to substantiate our findings.

Distinct outcomes of labetalol exposed infants: case reports and systematic review

BACKGROUND

The adverse effects of long-term maternal exposure of labetalol on neonates have been recognized clinically. But there are few systematic studies on their clinical demonstrations and potential mechanisms.

METHODS

A death case of an infant with long-term maternal labetalol exposure was reported and compared with two case reports from the literature. A systematic literature review was carried out followed by a retrospective analysis on neonatal labetalol withdrawal effects.

RESULTS

It was discovered that labetalol withdrawal effects initially cause various degrees of hypotension, hypoglycemia, and bradycardia among exposed neonates. Some life-threatening cases can also occur within 1 week after birth. Long-term maternal exposure of labetalol, preterm infants with birth asphyxia, acidosis, hypoalbuminemia, and cardiac defects are their primary features. Possible mechanisms were concluded as labetalol-induced effects on the vascular and sympathetic nervous system as well as tissue oxygen extraction.

CONCLUSIONS

Neonatal labetalol withdrawal effects include early-onset and late-onset demonstrations, the latter can be life-threatening. A possible mechanism is multiple factors induced imbalance of sympathetic homeostasis increases neonatal vulnerability to common stresses. Long-term exposed preterm infants complicated with asphyxia, acidosis, hypoalbuminemia and cardiac defects, should be provided with intense care during the first week after birth. Further work is necessary to enrich this hypothesis.

Neonatal haemodynamic effects following foetal exposure to labetalol in hypertensive disorders of pregnancy

OBJECTIVE

Hypertensive disorders of pregnancy (HDP) affect foetal outcome. Labetalol is frequently used to lower maternal blood pressure and prolong pregnancy. Conflicting evidence exists for specific neonatal side effects described after maternal labetalol treatment. Our aim was to investigate neonatal effects of foetal exposure to labetalol on cerebral oxygenation and extraction.

METHODS

In a prospective observational study, clinical characteristics, vital parameters and cerebral oxygen delivery and extraction were collected during the first 24 h of life in labetalol-exposed preterm neonates and compared with two control groups.

RESULTS

Twenty-two infants with a mean gestational age of 28.9 weeks, born from labetalol-treated mothers with HDP were included and matched with 22 infants with non-labetalol-treated mothers with HDP and 22 infants without maternal HDP. No significant differences between groups were found neither in heart rate, blood pressure and inotropic support, nor in mean regional cerebral oxygen saturation and fractional tissue oxygen extraction.

CONCLUSION

Foetal labetalol exposure associated effects on preterm heart rate, blood pressure, cerebral oxygenation and extraction are not demonstrated. Maternal disease severity seems to play a more important role in neonatal cerebral haemodynamics. Maternal labetalol treatment has no clinically important short term side effects in the preterm neonate.

Neonatal side effects of maternal labetalol treatment in severe preeclampsia

OBJECTIVE

Labetalol is often used in severe preeclampsia (PE). Hypotension, bradycardia and hypoglycemia are feared neonatal side effects, but may also occur in (preterm) infants regardless of labetalol exposure. We analyzed the possible association between intrauterine labetalol exposure and such side effects.

STUDY DESIGN

From 1 January 2003 through 31 March 2008, all infants from mothers suffering severe PE admitted to one tertiary care center were included. Severe PE was defined according to the International Society for the Study of Hypertension in Pregnancy (ISSHP) criteria. Infants exposed to labetalol in utero (labetalol infants) were compared with infants, who were not exposed to labetalol (controls). Neonatal records were reviewed for hypotension (RR<mean gestational age in weeks), bradycardia (heartrate<100/min) and hypoglycaemia (glucose<2.7 mmol/L) in the first 48 postnatal hours.

RESULTS

Of 109 infants, 55 had been exposed to labetalol, whereas 54 were not (controls). Gestational age at delivery and birthweight were similar in both groups (31.8 vs. 32.8 weeks (p=0.06) and 1510 vs. 1639 grams (p=0.25), respectively for the labetalol vs. control group). Hypotension occurred significantly more in conjunction with labetalol exposure (16, (29.1%) vs. 4 (7.4%); p=0.003), irrespective of the route of administration. Patent ductus arteriosus (PDA) was present in 9 (56%) of hypotensive labetalol infants compared to 1 (24%) infant in the hypotensive control group (NS). In a multivariate regression model, labetalol exposure, the need for intubation and PDA appeared independently associated with hypotension (P<0.001). Hypoglycemia occurred in 26 (47.3%) of labetalol infants and in 23 (42.6%) of control infants (p=0.62). Bradycardia occurred in 4 (7.3%) of labetalol infants and in 1 (1.9%) of control infants (p=0.18). Hypoglycemia was more common in premature infants (n=45 (48,9%) vs. n=4 (23.5%), p=0.05) in both labetalol and control infants.

CONCLUSION

Hypotension is more common after maternal labetalol exposure, regardless of the dosage and route of administration. The need for intubation and the presence of a PDA also play a role. Hypoglycemia is a very common finding in this population and is merely related to prematurity and independent of labetalol exposure as was the incidental occurrence of bradycardia. These findings on the neonatal side effects of maternal labetalol treatment in preeclampsia underline the importance of frequent blood glucose and blood pressure measurements in the first days of life, especially in intubated preterm infants with a PDA.

Cardiovascular Pharmacotherapeutic Considerations During Pregnancy and Lactation

Table 2 summarizes the recommendations regarding the use of cardiovascular drugs during pregnancy and lactation.

Plasma volume and blood pressure regulation in hypertensive pregnancy

BACKGROUND

Pre-eclampsia is a multisystem disorder, peculiar to and frequent in human pregnancy. It remains a leading cause of maternal and neonatal morbidity and mortality. Hemodynamic disturbances are the most prominent features of the syndrome.

PURPOSE

To provide an overview of plasma volume regulation and blood pressure control mechanisms outside pregnancy, and of the changes in normal pregnancies and in pregnancies complicated by hypertensive disorders. Furthermore, to discuss the rationale of several hemodynamic interventions.

RESULTS

In normal pregnancy, large cardiovascular changes take place. A generalized fall in vascular tone by systemic vasorelaxation causes increased blood volume, heart rate and cardiac output. In the preclinical phase, differences have been observed between normal and hypertensive pregnancies in the function of the autonomic nervous system, cardiac output and plasma volume, the volume remaining at the non-pregnant level. In the clinical phase of pre-eclampsia the typical case picture is one of a vasoconstrictive state with low plasma volume and cardiac output, high blood pressure and systemic vascular resistance in combination with signs of organ damage [proteinuria, hemolysis elevated liver enzymes low platelets (HELLP) syndrome]. Hemodynamic management is necessary in severe disease to prevent maternal complications. Management primarily focuses on pharmacological treatment of blood pressure. Clinicians make educated choices from a limited array of available drugs: beta-receptor antagonists, nifedipine, dihydralazine, methyldopa or ketanserine. Other drugs have restricted use in pregnancy. Management of low circulating volume with plasma expanders remains a subject of controversy.

Pharmacological treatment of severe hypertension in pregnancy and the role of serotonin(2)-receptor blockers

Hypertensive disorders of pregnancy are the leading cause of maternal and perinatal mortality and morbidity in developing and developed countries. The etiology of preeclampsia is still unknown. Delivering the baby is the only definite treatment. The benefits of acute pharmacological control of severe hypertension prior to and/or post-delivery are generally accepted. Most drugs commonly used in the management of severe hypertension in pregnancy have significant maternal and/or neonatal adverse side effects. Furthermore, some are not effective to acutely lower the blood pressure in patients with a hypertensive crisis. Until recently not one of the commonly used antihypertensive drugs has been tailored to the pathophysiology of severe preeclampsia, being a clinical syndrome characterized by endothelial cell dysfunction, vasospasm and platelet aggregation. Ketanserin, a serotonin(2)-receptor blocker, is a drug that appears to be tailored for treating this pregnancy-associated enthothelial cell dysfunction. The results of several prospective trials show that there is a definite place for serotonin(2)-receptor blockers in the treatment of pregnancy-induced hypertensive disorders. This review provides a summary on the more established drugs as well as on some of the newer antihypertensive drugs used in pregnancy with emphasis on the existing experience with ketanserin.

Adverse neonatal effects of maternal labetalol treatment

Two infants with features of severe beta adrenergic blockade, pericardial effusions, and myocardial hypertrophy were born to mothers receiving long term treatment with oral labetalol for hypertension in pregnancy. Labetalol was implicated in the aetiology of these problems. Pericardial effusion and myocardial hypertrophy have not been associated with labetalol toxicity in neonates.

Uterine and fetal hemodynamics and fetal cardiac function after atenolol and pindolol infusion. A randomized study

OBJECTIVE

To evaluate the short-term effects of intravenously given atenolol and pindolol on utero- and umbilicoplacental vascular impedance, fetal hemodynamics and cardiac function in patients suffering from pregnancy-induced hypertension.

STUDY DESIGN

A total of 24 women were randomized to receive atenolol or pindolol infusion. By using pulsed color Doppler techniques, uterine, placental arcuate, umbilical fetal middle cerebral and renal arteries were examined before, at the end and 30 min after the end of infusion. Pulsatility indices (PI) were calculated to assess vascular impedance. Fetal myocardial function was evaluated by using pulsed Doppler and M-mode echocardiography. Peak systolic velocities from the ascending aorta and pulmonary trunk, and also inner diameters and fractional shortenings of both ventricles were measured.

RESULTS

Both drugs significantly decreased maternal blood pressure. Immediately after the infusion, maternal heart rate was significantly decreased in both groups; but the decrease was clearer and lasted longer in the atenolol group. Pindolol caused no changes in utero- or umbilicoplacental vascular impedance, while atenolol increased it in the nonplacental uterine artery. After atenolol infusion, PI in the umbilical artery was higher than after pindolol. Pindolol had no effects on fetal hemodynamics, while atenolol decreased PI value in the fetal renal artery. Peak systolic velocity in the pulmonary trunk was decreased after atenolol. Pindolol did not affect the fetal cardiac function. In subgroups with originally increased utero- or umbilicoplacental vascular impedance, the responses in uterine and umbilical vascular impedance and in fetal hemodynamics and cardiac function after atenolol and pindolol were different compared to whole groups.

CONCLUSION

Differently acting antihypertensive agents seem to affect differently uteroplacental vascular impedance. Atenolol may have some direct effects on fetal hemodynamics and cardiac function. According to our results, pindolol seems to be more preferable in the treatment of pregnancy-induced hypertension than atenolol.

Use of glucagon to treat neonatal low-output congestive heart failure after maternal labetalol therapy

Labetalol is used to treat hypertensive crisis in women with preeclampsia. Glucagon was used as a nonselective beta-adrenergic agonist to treat a preterm infant with symptomatic beta-blockade caused by maternal labetalol therapy.

Perinatal results of hemodynamic and conservative temporizing treatment in severe pre-eclampsia

OBJECTIVE

To evaluate maternal and perinatal outcome of hemodynamic temporizing management in severe pre-eclampsia.

DESIGN

Study group of 57 pre-eclamptic women, gestational age 35 weeks or less, treated with plasma volume expansion and vasodilatation under invasive hemodynamic monitoring, retrospectively matched with a control group treated in another center without volume expansion and invasive monitoring.

RESULTS

In both groups pregnancy was prolonged with 10-11 days. Maternal morbidity was low in both groups. No complications of hemodynamic monitoring were observed. Perinatal mortality was not significantly different between the study group (7.1%) and the control group (14.3%). SGA-infants were significantly less frequent in the study group (9%) than in controls (33%).

CONCLUSION

Temporizing treatment of patients with early severe pre-eclampsia, with or without plasma volume expansion and invasive hemodynamic monitoring, may reduce neonatal mortality and morbidity. The difference in birthweight between study group and control group may be an effect of the therapy or may be caused by selection bias. The perinatal outcome in the study group suggests that there may be a subgroup of patients who might benefit from hemodynamic treatment.

Value of absent or retrograde end-diastolic flow in fetal aorta and umbilical artery as a predictor of perinatal outcome in pregnancy-induced hypertension

There is insufficient data on the value of absent or retrograde end-diastolic flow (AREDF) in the fetal umbilical artery, descending aorta and aortic arch to predict perinatal outcome. In this prospective investigation, 65 pregnant women between 24 and 34 weeks' gestation with pregnancy-induced hypertension were studied by color Doppler echocardiography. Pregnancies leading to birth at or before 34.0 gestational weeks (23 with and 19 without AREDF) were included in the outcome analysis. Fetuses with AREDF were delivered at earlier gestational ages (p = 0.006). They had a higher incidence of gastrointestinal complications (p = 0.01), bronchopulmonary dysplasia (p = 0.03), intraventricular hemorrhage (p = 0.03) and vascular hypotension (p = 0.03) than those without AREDF. The presence of AREDF was associated with a mortality rate of 30%, whereas in fetuses without AREDF there was no mortality (p = 0.01). Using logistic regression and taking into consideration various perinatal factors, the presence of AREDF (p = 0.03) and early gestational age (p = 0.0001) were associated with serious neonatal diseases or death. A reverse diastolic flow in the aortic isthmus was registered in five fetuses; three died during the perinatal period and one was severely damaged. According to our results, AREDF, particularly with the appearance of reverse diastolic flow in the isthmus of the aortic arch, is a predictor of poor neonatal outcome.

Perinatal factors associated with retinopathy of prematurity

The etiology of retinopathy of prematurity appears to be multifactorial. Introduction of new treatments in neonatal care may add new risk factors. We have analyzed the relationship between 42 perinatal factors and the development of retinopathy of prematurity in 78 infants with a birth weight < 1501 g and/or gestational age < 33 weeks. We have also applied a chronological analysis of the maximum and minimum pO2 and pCO2 values. Retinopathy of prematurity was seen in 37 of 78 infants (47.4%). Nineteen factors were found to be related to the development of retinopathy of prematurity. However, when step-wise logistic regression analysis was used, only birth weight, number of days of oxygen therapy and use of beta-blocking agents by the mother before birth were found to be associated with the development of retinopathy of prematurity. The results suggest that medication with beta blockers immediately before birth should be used cautiously.

Changes in adrenoceptors and monoamine metabolism in neonatal and adult rat brain after postnatal exposure to the antihypertensive labetalol

1. The purpose of the present study was to investigate the acute (single injection), direct (chronic treatment) and the long-lasting effects after exposure to the alpha 1/beta-adrenoceptor antagonist labetalol during rat brain development on adrenoceptors and monoamine metabolism. 2. In 10-day-old rat pups, subcutaneously administered labetalol (10 mg kg-1) passed the blood-brain barrier, reaching a level of 2.1 micrograms g-1 tissue in the brain 90 min after injection. 3. Chronic labetalol treatment (10 mg kg-1, s.c., twice daily) during the first 10 days of life significantly increased alpha 1-adrenoceptor binding in the hypothalamus (+39%), but not in the occipital cortex. 4. This chronic postnatal labetalol treatment did not result in long-lasting changes in alpha 1- and beta-receptors measured on day 60. 5. A single labetalol injection (10 mg kg-1, s.c.) on postnatal day 10 significantly increased noradrenaline (NA) metabolism in all brain regions tested (+25 to 105%), but had no effects on 5-hydroxytryptamine (5-HT) or dopamine metabolism. 6. Chronic labetalol treatment between postnatal (PN) days 1 and 10 also increased NA metabolism on PN 10 (3-methoxy-4-hydroxyphenylglycol (MHPG)/NA, +20 to 100%), suggesting that tolerance to the acute effect of labetalol did not occur. A slight increase in 5-HT metabolism (20%) was induced by the chronic labetalol treatment in the hippocampus and meso-limbic system. 7. In general, long-lasting effects on NA metabolism could not be detected on day 60 more than one month after the treatment. However, 5-HT metabolism was significantly increased in all four brain regions measured (+20 to 70%). 8. We conclude that chronic labetalol exposure during early postnatal rat brain development does not cause long-lasting changes in beta-receptor number or NA metabolism, but appears to be critical for the rate of 5-HT metabolism in later life.

Maternal and fetal haemodynamics in hypertensive pregnancies during maternal treatment with intravenous hydralazine or labetalol

Intravenous treatment with 10 mg of hydralazine or 100 mg of labetalol was randomly allocated to 30 hypertensive pregnant women. Umbilical artery flow velocity waveforms were recorded using a pulsed Doppler duplex scanner (ATL Mk V) and umbilical artery pulsatility index (PI) and fetal heart rate (FHR) were derived from these recordings. Maternal blood pressure decreased significantly after both drugs. Maternal pulse rate increased after hydralazine but did not change significantly after labetalol. FHR did not change significantly after hydralazine but decreased after labetalol. PI decreased after hydralazine and increased after labetalol--most fetuses showed little change but a few in each group showed large changes in PI, as did two of five additional patients studied. We attributed the decrease in PI in some fetuses after hydralazine to vasodilation, and the increase in PI in some fetuses after labetalol to vasoconstriction in the fetoplacental circulation, suggesting that fetal beta-blockade may occur after maternal treatment with labetalol.

Half-life of maternal labetalol in a premature infant

Intra-uterine heart arrhythmia, postpartal respiratory insufficiency, bradycardia and hypoglycaemia were observed in a premature infant (37 weeks gestational age) delivered by a caesarian section. The mother had been treated with adequate doses of labetalol because of pregnancy-induced hypertension and her plasma concentration was found to be 89 micrograms/l one day after delivery. The half-life of labetalol in the plasma of the infant was found to be approximately 24 h, i.e. substantially longer than in normal adults. The half-life of labetalol in newborn premature infants may be prolonged as compared to normal adults. More studies are required regarding the pharmacokinetics of this agent in premature infants and newborn babies.