Recent indomethacin tocolysis is not associated with neonatal complications in preterm infants

Antenatal exposure to indomethacin increases the risk of severe intraventricular hemorrhage, necrotizing enterocolitis, and periventricular leukomalacia: a systematic review with metaanalysis

OBJECTIVE

The purpose of this study was to provide an updated summary of the literature regarding the effects of tocolysis with indomethacin on neonatal outcome by systematically reviewing previously and recently reported data.

STUDY DESIGN

All previously reported studies pertaining to indomethacin tocolysis and neonatal outcomes along with recently reported data were identified with the use of electronic databases that had been supplemented with references that were cited in original studies and review articles. Observational studies that compared neonatal outcomes among preterm infants who were exposed and not exposed to indomethacin were included in this systematic review. Data were extracted and quantitative analyses were performed on those studies that assessed the neonatal outcomes of patients that received antenatal tocolysis with indomethacin.

RESULTS

Twenty-seven observational studies that met criteria for systematic review and metaanalysis were identified. These studies included 8454 infants, of whom 1731 were exposed to antenatal indomethacin and 6723 were not exposed. Relative risks with 95% confidence intervals were calculated for dichotomous outcomes with the use of random and fixed-effects models. Metaanalysis revealed no statistically significant differences in the rates of respiratory distress syndrome, patent ductus arteriosus, neonatal mortality rate, neonatal sepsis, bronchopulmonary dysplasia, or intraventricular hemorrhage (all grades). However, antenatal exposure to indomethacin was associated with an increased risk of severe intraventricular hemorrhage (grade III-IV based on Papile's criteria; relative risk, 1.29; 95% confidence interval, 1.06-1.56), necrotizing enterocolitis (relative risk, 1.36; 95% confidence interval, 1.08-1.71), and periventricular leukomalacia (relative risk, 1.59; 95% confidence interval, 1.17-2.17).

CONCLUSION

The use of indomethacin as a tocolytic agent for preterm labor is associated with an increased risk for severe intraventricular hemorrhage, necrotizing enterocolitis, and periventricular leukomalacia.

What really causes necrotising enterocolitis?

Background. One of the most serious gastrointestinal disorders occurring in neonates is necrotising enterocolitis (NEC). It is recognised as the most common intra-abdominal emergency and is the leading cause of short bowel syndrome. With extremely high mortality and morbidity, this enigmatic disease remains a challenge for neonatologists around the world as its definite aetiology has yet to be determined. As current medical knowledge stands, there is no single well-defined cause of NEC. Instead, there are nearly 20 risk factors that are proposed to increase the likelihood of developing NEC. Aims and Objectives. The aim of this project was to conduct a comprehensive literature review around the 20 or so well-documented and less well-documented risk factors for necrotising enterocolitis. Materials and Methods. Searches of the Medline, Embase, and Science direct databases were conducted using the words "necrotising enterocolitis + the risk factor in question" for example, "necrotising enterocolitis + dehydration." Search results were ordered by relevance with bias given to more recent publications. Conclusion. This literature review has demonstrated the complexity of necrotising enterocolitis and emphasised the likely multifactorial aetiology. Further research is needed to investigate the extent to which each risk factor is implicated in necrotising enterocolitis.

The risk of necrotizing enterocolitis after indomethacin tocolysis

BACKGROUND

Postnatal indomethacin is reportedly associated with an increased incidence of necrotizing enterocolitis (NEC) in preterm infants. Because indomethacin readily crosses the placenta, we hypothesized that antenatal indomethacin (AI) would increase the risk for NEC in preterm infants.

OBJECTIVE

The goal of this study was to explore the association between AI and NEC in preterm infants.

METHODS

Medical records of preterm infants, 23 to 32 weeks' gestational age, without major congenital anomalies, were reviewed. Maternal and neonatal data were abstracted. Association of AI within 15 days before delivery (predictor variable) and classification of NEC according to modified Bell's stage 2a or higher in the first 15 days after delivery (early NEC [primary outcome variable]) was explored by using bivariate analyses, multivariate logistic regression, and propensity score analysis.

RESULTS

Of 628 eligible infants, 63 received AI and 28 developed early NEC. AI exposure was significantly associated with multiple gestation, race, antenatal corticosteroids and magnesium sulfate, lower birth weight and gestational age, umbilical arterial catheter placement, respiratory distress syndrome, postnatal vasopressors and antibiotics, patent ductus arteriosus, sepsis, NEC, intraventricular hemorrhage, and mortality. On multivariate logistic regression controlling for covariates, AI was significantly associated with early NEC (adjusted odds ratio: 7.193 [95% confidence interval: 2.514-20.575]; number needed to harm: 5). The results remained significant when analyses were repeated using AI exposure within 5 days before delivery as a predictor variable; on analyses stratified according to gestational age; and on propensity score analysis.

CONCLUSIONS

AI was associated with NEC in preterm infants in the first 15 days of life in this study, as were multiple other clinical factors.

Prenatal or postnatal indomethacin exposure and neonatal gut injury associated with isolated intestinal perforation and necrotizing enterocolitis

OBJECTIVE

To examine the role of indomethacin in neonatal gut injury.

STUDY DESIGN

Infants born at gestational age 23 weeks and with birth weights 400-1200 g were included in this prospective prevalence study of neonatal gut injury. Infants with isolated intestinal perforation (IIP) confirmed at laparotomy or at autopsy or with necrotizing enterocolitis (NEC) were identified. Data were abstracted bi-weekly.

RESULT

Among 992 study infants, 58 infants exposed solely to prenatal indomethacin did not show an increased rate of neonatal gut injury. Any postnatal indomethacin exposure (n=611) increased the odds of IIP (OR 4.17, CI, 1.24-14.08, P=0.02) but decreased the odds of NEC (OR 0.65, CI 0.43-0.97, P=0.04). There was a negative association between the timing of indomethacin-exposure and the odds of developing IIP (OR 0.30, CI 0.11-0.83, P=0.02). Compared with NEC, IIP occurred at an earlier age (P<0.05) and was more common (P<0.05) among infants who received early indomethacin (first dose at <12 h of age) to prevent intraventricular hemorrhage than among infants who were treated with late indomethacin for closure of a patent ductus arteriosus (PDA). Unlike the classic hemorrhagic ischemic lesions of NEC in which large areas of tissue were inflamed or necrotic, the IIP lesions were small and discrete.

CONCLUSION

Early (<12 h) postnatal indomethacin exposure was associated with an increased odds of IIP in very low birth weight infants whereas its later use for closure of a PDA appeared to provide protection against NEC. The paradoxical effect of the timing of indomethacin on IIP versus on NEC may be related to the different pathogeneses of the two diseases. Our findings also suggest that PDA may contribute to NEC.

Reversible ductus arteriosus constriction due to maternal indomethacin after fetal intervention for hypoplastic left heart syndrome with intact/restrictive atrial septum

OBJECTIVE

Fetal cardiac intervention (FCI) has been performed at our center in selected fetuses with complex congenital heart disease since 2000. Most interventions are performed in fetuses with a ductus arteriosus (DA)-dependent circulation. Indomethacin promotes closure of the DA in newborns and in fetal life, a potentially life threatening complication in fetuses with ductus-dependent congenital heart disease.

METHODS

We reviewed our experience with FCI with a focus on the frequency, features, and clinical course of ductal constriction. Fetuses undergoing FCI receive comprehensive pre- and postoperative cardiac and cerebral ultrasound evaluation, approximately 24 hours before and after the procedure, including imaging of DA flow and Doppler assessment of the umbilical artery and vein, ductus venosus, and, since 2004, the middle cerebral artery.

RESULTS

Among 113 fetuses that underwent FCI, 24 of which were older than 28 0/7 weeks gestation, 2 were found to have DA constriction due to indomethacin therapy within 24 hours of intervention. Both of these were 30-week fetuses with hypoplastic left heart syndrome and restrictive or intact atrial septum. The DA was stenotic by spectral and color Doppler, and middle cerebral and umbilical artery pulsatility indexes were depressed. After discontinuation of indomethacin, the Doppler indices improved or normalized.

CONCLUSION

Close echocardiographic monitoring of fetal Doppler flow velocities is very important after fetal intervention and indomethacin treatment, as the consequences of DA constriction in a fetus with hypoplastic left heart syndrome are potentially lethal. Sonographic evaluation should include measurement of cerebral and umbilical arterial flow velocities as well as color and spectral Doppler interrogation of the DA.

Goals and strategies for prevention of preterm birth: an obstetric perspective

Complications of prematurity surpass congenital malformations as the leading cause of infant mortality in the United States. Since 1990, there has been a steady rise in preterm birth, alarming health professionals from all disciplines. This review from a prenatal perspective confirms those concerns and describes the risks and opportunities that may attend efforts to improve the health of fetuses, newborns, and infants. Fetal and live-born outcomes are included.

Metaanalysis of the effect of antenatal indomethacin on neonatal outcomes

OBJECTIVE

The objective of the study was to determine whether indomethacin used as a tocolytic agent is associated with adverse neonatal outcomes.

STUDY DESIGN

We used published guidelines of the Metaanalysis of Observational Studies in Epidemiology Group (MOOSE) to perform the metaanalysis. The search strategy used included computerized bibliographic searches of MEDLINE (1966-2005), PubMed (1966-2005), abstracts published in Obstetrics and Gynecology (1991-2005), abstracts published in Pediatric Research (1991-2005), and references of published manuscripts. Study inclusion criteria were publication in English, more than 30 deliveries less than 37 weeks' gestation, and meeting diagnostic criteria for individual neonatal outcomes. Exclusion criteria included case reports, case series, and multiple publications from the same author. Metaanalysis was performed using random effects model if there were more than 2 observational studies for a specific outcome. Eggers test was performed to exclude publication bias. Sensitivity analysis was performed to evaluate the effect of antenatal steroid exposure, gestation, and recent antenatal indomethacin exposure (duration of 48 hours or more between the last dose and delivery).

RESULTS

Fifteen retrospective cohort studies and 6 case-controlled studies met inclusion criteria. Antenatal indomethacin was associated with an increased risk of periventricular leukomalacia (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.3-3.1). Recent exposure to antenatal indomethacin was associated with necrotizing enterocolitis (OR, 2.2; 95% CI; 1.1-4.2). Antenatal indomethacin was not associated with intraventricular hemorrhage, patent ductus arteriosus, respiratory distress syndrome, bronchopulmonary dysplasia, and mortality.

CONCLUSION

Antenatal indomethacin may be associated with an increased risk of periventricular leukomalacia and necrotizing enterocolitis in premature infants and therefore should be used judiciously for tocolysis.

Pharmacological prevention of prematurity

The acute treatment of premature labour is successful for delaying delivery for short periods of time. Acute tocolysis does not have a significant impact on perinatal outcome. This is likely to be because the process leading to labour occurs over a longer timeframe and therefore therapies instigated as preventative measures are more likely to be successful in delaying delivery. Identification of women at risk of preterm birth is essential to ensure therapies are targeted appropriately. Risk assessments for prediction include previous obstetric history, previous episode of threatened preterm labour, fetal fibronectin status and cervical length. Several groups of pharmacological agents have been studied for the prophylactic treatment of preterm labour. There is no evidence to support the use of tocolytics such as beta-mimetics and oxytocin receptor antagonists. Current studies of calcium channel blockers are too small to draw final conclusions. Non-steroidal anti-inflammatory drugs are associated with side effects on the fetal renal system and ductus arteriosus, making them suitable only for long term use in pregnancy with close ultrasound surveillance. Antibiotics used early in pregnancy in women with abnormal vaginal flora may reduce the risk of preterm birth; however, in women with other risk factors for preterm birth, metronidazole may be associated with an increased risk. The use of progesterone in women with a history of very early preterm labour is likely to be beneficial for preventing preterm labour.

Effects of maternally administered drugs on the fetal and neonatal kidney

The number of pregnant women and women of childbearing age who are receiving drugs is increasing. A variety of drugs are prescribed for either complications of pregnancy or maternal diseases that existed prior to the pregnancy. Such drugs cross the placental barrier, enter the fetal circulation and potentially alter fetal development, particularly the development of the kidneys. Increased incidences of intrauterine growth retardation and adverse renal effects have been reported. The fetus and the newborn infant may thus experience renal failure, varying from transient oligohydramnios to severe neonatal renal insufficiency leading to death. Such adverse effects may particularly occur when fetuses are exposed to NSAIDs, ACE inhibitors and specific angiotensin II receptor type 1 antagonists. In addition to functional adverse effects, in utero exposure to drugs may affect renal structure itself and produce renal congenital abnormalities, including cystic dysplasia, tubular dysgenesis, ischaemic damage and a reduced nephron number. Experimental studies raise the question of potential long-term adverse effects, including renal dysfunction and arterial hypertension in adulthood. Although neonatal data for many drugs are reassuring, such findings stress the importance of long-term follow-up of infants exposed in utero to certain drugs that have been administered to the mother.

Vaginal versus oral indomethacin in a rabbit model for non-infection-mediated preterm birth: an alternate tocolytic approach

OBJECTIVE

We examined the hypotheses that vaginal indomethacin is more effective for prolonging gestation, and mediates its tocolytic actions via changes in cervical matrix metalloproteinase (MMP) activity, compared to oral.

STUDY DESIGN

Pregnant rabbits induced with mifepristone received oral or vaginal indomethacin; or oral or vaginal vehicle once daily for 2 days. Premature delivery, fetal ductus arteriosus, and cervical MMP activity were assessed.

RESULTS

Vaginal indomethacin delayed delivery >72 hours in 100% of the rabbits, extending gestation to 28.2 +/- 0.5 (P < .01) versus 26.4 +/- 0.3, 25.8 +/- 0.5, and 26.5 +/- 0.3 days, for vaginal placebo, oral indomethacin, and oral vehicle, respectively. Fetal ductus arteriosus was patent in all groups. Vaginal indomethacin decreased MMP-1, -8, and -9 activities and increased TIMP-1 levels in the cervix.

CONCLUSION

Vaginal indomethacin is more effective than oral for prolonging gestation in the rabbit. Its tocolytic effects may be mediated, in part, by alterations in cervical MMP activity.

Risk-benefit effects of tocolytic therapy

Tocolytics are potent drugs that are used to interdict preterm labour. Although all of these agents have some side effects, if not frankly adverse effects under certain clinical situations, two of these drugs, the beta-mimetics and magnesium sulphate (MgSO(4)), have been found to have considerable potential for adverse maternal cardiovascular and respiratory effects. Furthermore, magnesium sulphate has been shown to have harmful, indeed, sometimes lethal, effects in some babies. Although less well established, NSAIDs, the most common example of which is indomethacin, also have some important adverse effects in fetuses. Within the limits of contemporary scientific knowledge, calcium channel blockers, such as nifedipine, appear to be among the more efficacious and safer drugs that are currently being used for tocolysis.

Antiprostaglandin Drugs

Prostaglandins create conditions favorable for activation and stimulation of labor and are key components in the process of both normal and preterm labor. Antiprostaglandins may be useful in the prevention of preterm labor because they inhibit prostaglandin synthetase and reduce prostaglandin formation. The antiprostaglandin indomethacin has been the most studied as a tocolytic agent, but its success is limited because of fetal and neonatal complications associated with prolonged use. More recently, the cyclooxygenase-2 specific agents have been investigated because of their improved side effect profile. This article discusses the process of prostaglandin production and inhibition and reviews and critiques the available literature investigating the efficacy and safety of indomethacin and the newer cyclooxygenase-2 agents.

Assessing the Neonatal Safety of Indomethacin Tocolysis

OBJECTIVE

To systematically review and summarize the medical literature regarding the effects of tocolysis with indomethacin on neonatal outcome.

DATA SOURCES

We supplemented a search of entries in electronic databases with references cited in original studies and review articles to identify studies pertaining to indomethacin tocolysis and neonatal outcome.

METHODS OF STUDY SELECTION

We evaluated, abstracted data, and performed quantitative analyses in studies assessing the neonatal outcomes of patients undergoing tocolysis with indomethacin. Observational studies and randomized trials were included in this systematic review.

TABULATION, INTEGRATION, AND RESULTS

Forty-six studies were identified, 28 of which met criteria for systematic review and meta-analysis. These 28 studies included 6,008 infants. Of these infants, 1,621 were exposed to indomethacin for tocolysis antenatally; 4,387 infants not exposed to indomethacin served as the comparison group. An estimate of pooled odds ratios with 95% confidence intervals was calculated for dichotomous outcomes using random- and fixed-effects models. Observational studies and randomized trials were analyzed separately. Pooled estimates from observational studies and randomized trials revealed no significant differences in the rates of intraventricular hemorrhage, patent ductus arteriosus, necrotizing enterocolitis, or neonatal mortality between infants exposed to indomethacin antenatally and those not exposed. Meta-analysis of randomized trials revealed increased risk of bronchopulmonary dysplasia. However, the meta-analysis included only 3 randomized clinical trials, one of which showed increased risk. An association of bronchopulmonary dysplasia and indomethacin use was not noted in our analysis of observational studies.

CONCLUSION

Although our pooled results did not identify significantly increased risks of adverse effects, the limited statistical power of published randomized trials does not allow us to exclude the possibility that indomethacin tocolysis increases the risk of adverse neonatal outcomes.

Outcome of very low birth weight infants exposed to antenatal indomethacin for tocolysis

OBJECTIVE

Beginning in October 1995, and for several years thereafter, our institution used indomethacin as a first-line tocolytic drug. Our purpose is to compare the outcomes of very low birth weight infants who were exposed to antenatal indomethacin with those who were not exposed to this therapy.

STUDY DESIGN

We used our center's component of the NICHD Neonatal Research Network's Generic Data Base which recorded the outcomes of all live born infants weighing less than 1500 g over a 5-year period. We abstracted data concerning neonatal morbidity (death, Grades III to IV intraventricular hemorrhage (IVH), necrotizing enterocolitis and patent ductus arteriosus), as well as other factors including gestational age, birth weight, antenatal corticosteroid treatment and maternal hypertension or pre-eclampsia. Univariate analysis was performed using Fisher's exact test. Multivariate analysis using logistic regression was performed to control for confounding factors.

RESULTS

A total of 85 infants who were exposed to antenatal indomethacin were compared to 464 infants who were not exposed to the drug. In the univariate analysis, antenatal indomethacin exposure was not associated with a significant increase in the incidence of necrotizing enterocolitis or patent ductus arteriosus. The incidence of Grades III to IV IVH was 17.9% in those infants exposed to antenatal indomethacin compared to 7.1% in the nonexposed infants (p=0.008). The incidence of neonatal death in the exposed infants was 27.7 versus 16.4 in the nonexposed infants (p=0.02). After controlling for antenatal corticosteroids, maternal pre-eclampsia, gestational age and birth weight, antenatal indomethacin was significantly associated with an increased incidence of IVH, but not neonatal death.

CONCLUSION

Antenatal indomethacin was associated with significantly higher rates of IVH. Additional studies assessing the potential risks of indomethacin tocolysis are needed before it is used as a first-line tocolytic therapy.

Persistent pulmonary hypertension in a premature newborn after 16 hours of antenatal indomethacin exposure

Premature constriction of the fetal ductus arteriosus has been described with long-term indomethacin therapy, but not in fetuses who have been exposed to the drug for less than 72 hours. The sensitivity of the ductus to extended indomethacin tocolysis increases with advancing gestational age. For this reason, it is recommended that indomethacin not be used beyond 31 weeks of gestation. In the present case the gestational age of the patient was 27 weeks and the period of indomethacin exposure was only 16 hours. Our observations of pulmonary hypertension in this case suggest that administration of indomethacin even hours before delivery can significantly affect the ductus arteriosus and the pulmonary vasculature.

Tocolyse dans les situations pathologiques particulières

In twin pregnancies, the use of beta-adrenergics is associated with a significantly higher incidence of cardiovascular complications, and calcium channel blockers as well as oxytocin antagonists currently appear as first line agents. After extreme preterm delivery of the first twin and in selected patients, the birth of second twin may be delayed with a mean gain of 10-50 days. In cases of symptomatic placenta previa with mild-to-moderate bleeding, tocolytic agents may be associated with a prolongation of pregnancy and increased birth weight without significant impact on frequency or severity of bleeding. Calcium channel blockers are the drugs of choice in the event of diabetes. Indomethacin is a potent tocolytic, in particular in patients with polyhydramnios. However, it may cause oligohydramnios, premature closure of the ductus arteriosus and intrauterine fetal death when high doses are administered for a duration exceeding 48 to 72 hours, particularly beyond 32 weeks' gestation. The neonatal complications of indomethacin occur frequently. Tocolysis appears to reduce the failure rate of external cephalic version at term.

Acute management of preterm labor

We are continually reminded that the preterm birth rate has failed to improve; in fact, it has increased over the last 20 years. Much of this increase is related to the tremendous strides made by neonatologists and the resulting increased willingness of obstetricians to deliver preterm babies from hostile intrauterine environments. However, there is still much to learn concerning the pathogenesis, accurate early detection, treatment, and prevention of spontaneous preterm labor. This article concentrates on the clinical diagnosis and acute management of this enigmatic clinical problem.

Prostaglandin inhibitors in preterm labour

Prematurity accounts for the majority of neonatal morbidity and mortality in the developed world. The process of labour resembles inflammation, with prostaglandin and cytokine production both before and during labour. Anti-inflammatory drugs therefore have the potential to prevent preterm delivery. Indomethacin is the only tocolytic drug proven to delay delivery beyond 37 weeks and to reduce the incidence of low birth weight (<2500 g). There are, however, fetal side-effects such as ductal constriction and impaired renal function associated with its use. It is the type 2 isoform of cyclo-oxygenase (COX-2), which is important for the production of prostaglandins within intrauterine tissues and that up-regulation of COX-2 is associated with labour. Although indomethacin is currently the most common non-steroidal anti-inflammatory drug (NSAID) used in the treatment of preterm labour, it was hoped that COX-2-selective drugs, used as tocolytics, would target COX-2 activity and potentially spare COX-1-specific fetal side-effects. Experience with sulindac and nimesulide has been linked with both constriction of the ductus arteriosus and oligohydramnios. It is unclear whether this is due to COX-2-dependent side-effects, or due to accumulation of drug in the fetal circulation leading to levels that would cause COX-1 inhibition. Currently, the use of COX-2-selective drugs should therefore be confined to randomized controlled trials.

Neonatal outcome after exposure to indomethacin in utero: a retrospective case cohort study

OBJECTIVE

This study was undertaken to determine the clinical outcome for neonates who were exposed to indomethacin during gestation.

STUDY DESIGN

We identified 124 infants with in utero exposure to indomethacin and matched them to 124 infants whose mothers did not receive indomethacin. The two groups were matched for gestational age at birth, sex, and exposure to antenatal betamethasone. Sixty-two of the indomethacin-exposed infants were born within 48 hours of last exposure. These infants were also compared with their matched controls.

RESULTS

There were no significant differences between the indomethacin-exposed infants and control infants in birth weight, Apgar scores, frequency of cesarean section deliveries, and multiple gestation. The incidence of respiratory distress syndrome, need for surfactant treatment, patent ductus arteriosus, necrotizing enterocolitis, and intraventricular hemorrhage was similar between the indomethacin-exposed group and the control group. Indomethacin-exposed infants who were born within 48 hours of last exposure had similar incidence of respiratory distress syndrome but greater need for surfactant treatment (P=.02) compared with controls. All other complication rates were similar.

CONCLUSION

Indomethacin exposure in our study was not associated with increased neonatal complications for infants delivered within or beyond 48 hours of last exposure.

Reproductive considerations: mare and stallion

Functional alterations within the reproductive system and in other supporting systems may limit the reproductive capacity of geriatric patients; however, the age of onset and degree of compromise show wide individual variation. Aging of the hypothalamopituitary-ovarian axis in the mare manifests as delayed entry to the breeding season, prolonged follicular phases, reduced response to ovulation induction, irregular cycles, oocyte defects, increased early embryonic death, and, eventually, persistent anestrus. Aging of the reproductive tract may increase her susceptibility to endometritis, compromise placental formation with long-term effects on the fetus and viability of the resulting foal, increase her risk of ascending placentitis, alter gestation length, and make her more prone to catastrophic rupture of the uterine arteries at the time of parturition. Effects on the stallion are less well documented but include a reduction in sperm output associated with progressive testicular degeneration and potential compromise of libido and mating ability that is often associated with degenerative conditions of the musculoskeletal system.

The effect of in utero exposure to indomethacin on the need for surgical closure of a patent ductus arteriosus in the neonate

OBJECTIVE

Our purpose was to determine the effect of in utero exposure to indomethacin on the need for surgical closure of a patent ductus arteriosus (PDA).

STUDY DESIGN

Perinatal variables were compared between infants at <32 weeks who required surgical closure of PDA after failed medical management and those who did not. Statistical analysis was performed by Student t, Mann-Whitney, chi(2), and multiple logistic regression tests.

RESULTS

Eight of 77 infants with PDA failed therapy and required surgery. Maternal demographics, gestational age, birth weight, and delivery route were similar in both groups. In utero exposure to indomethacin was more common in neonates requiring surgery versus those who did not, particularly when exposure was for >72 hours (50.0% vs 8.7%, odds ratio 10.5, 95% CI 1.6-72.1, P =.008).

CONCLUSION

Need for surgical closure of PDA appears to be increased by in utero indomethacin exposure. These findings should be considered in the overall context of the risk versus benefits of tocolysis.

Adverse and beneficial effects of tocolytic therapy

In addition to questions raised about the efficacy of many tocolytics, appropriate concern has been voiced about the safety of these potent drugs. Although some degree of risk for adverse effects with drugs promising a strong therapeutic effect can be accepted, caution needs to be exercised when benefits are marginal or unproven. Unfortunately, some of the tocolytics, most notably the betamimetics and magnesium sulfate, have been found to have considerable potential for adverse maternal cardiovascular and respiratory effects. Although less clearly established, the use of indomethacin appears to be associated with increased fetal and neonatal risks. Concerning magnesium sulfate, in addition to the well-known maternal effects, the accumulating evidence showing an increased frequency of adverse outcomes in the fetus and neonate has led to the recommendations to abandon its use entirely as a tocolytic. Given the limitations of our current state of knowledge, nifedipine would appear to be among the more efficacious and safer tocolytics available to use when properly indicated.

Prostaglandin inhibitors as tocolytic agents

Indomethacin, a nonspecific prostaglandin synthetase inhibitor, gained popularity several decades ago as a potent tocolytic agent. This popularity, however, was tempered by concerns over fetal and neonatal complications associated with its use. However, with better recognition of the safety limitations, there has been a renewed interest in using indomethacin for acute tocolysis. More recently, the tocolytic potential of cyclooxygenase-2 (COX-2) specific inhibitors has gained much interest as well as the theoretical minimization of side effects associated with these agents. This article reviews the pharmacology and efficacy of indomethacin and some of the newer cyclooxygenase-2 inhibitors, and discusses the potential adverse fetal and neonatal effects associated with their use. Guidelines will be presented that will assist theclinician in using indomethacin as an effective tocolytic while avoiding untoward effects.

The controversy surrounding indomethacin for tocolysis

Indomethacin is a prostaglandin synthetase inhibitor sometimes used for tocolysis. Several placebo-controlled trials and trials comparing indomethacin to other potential first-line tocolytic agents support its efficacy for delaying delivery for >48 hours. Recent observational studies, however, have raised concerns about the safety of indomethacin, implicating it with increased rates of intraventricular hemorrhage and necrotizing enterocolitis. Careful analysis of these observational studies suggests that these results should be viewed with caution, because of uncontrolled confounding by indication. A recent decision analysis supports the risk/benefit analysis of indomethacin in this setting. Still, the future of indomethacin in preterm labor should be guided by well-designed prospective clinical trials. Such studies are underway.