Maternal Transdermal Nitroglycerin Use and Early Childhood Development

Nitric oxide donors for treating preterm labour

BACKGROUND

A number of tocolytics have been advocated for the treatment of threatened preterm labour in order to delay birth. The rationale is that a delay in birth may be associated with improved neonatal morbidity or mortality. Nitric oxide donors, such as nitroglycerin, have been used to relax the uterus. This review addresses their efficacy, adverse effects and influence on neonatal outcome.

OBJECTIVES

To determine whether nitric oxide donors administered in threatened preterm labour are associated with a delay in birth, adverse effects or improved neonatal outcome.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 December 2013).

SELECTION CRITERIA

Randomised controlled trials of nitric oxide donors administered for tocolysis.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data.

MAIN RESULTS

Twelve trials, including a total of 1227 women at risk of preterm labour, contributed data to this updated review. The methodological quality of trials was mixed; trials comparing nitric oxide donors with other types of tocolytics were not blinded and this may have had an impact on findings.Three studies compared nitric oxide donors (glyceryl trinitrate (GTN)) with placebo. There was no significant evidence that nitric oxide donors prolonged pregnancy beyond 48 hours (average risk ratio (RR) 1.19, 95% confidence interval (CI) 0.74 to 1.90, two studies, 186 women), and although for most adverse effects there was no significant difference between groups, women in the active treatment group in one study were at higher risk of experiencing a headache. For infant outcomes there was no significant evidence that nitric oxide donors reduced the risk of neonatal death or serious morbidity (stillbirth RR 0.36, 95% CI 0.01 to 8.59, one study, 153 infants; neonatal death RR 0.43, 95% CI 0.06 to 2.89, two studies, 186 infants). One study, using a composite outcome, reported a reduced risk of serious adverse outcomes for infants in the GTN group which approached statistical significance (RR 0.29, 95% CI 0.08 to 1.00, 153 infants). Overall, these studies were underpowered to identify differences between groups for most outcomes.When nitric oxide donors were compared with other tocolytic drugs there was no significant evidence that nitric oxide donors performed better than other tocolytics (betamimetics, magnesium sulphate, a calcium channel blocker or a combination of tocolytics) in terms of pregnancy prolongation, although nitric oxide donors appeared to be associated with a reduction in most adverse effects, apart from headache. There was no significant difference between groups for infant morbidity or mortality outcomes.

AUTHORS' CONCLUSIONS

There is currently insufficient evidence to support the routine administration of nitric oxide donors in the treatment of threatened preterm labour.

Transdermal nitroglycerin for the treatment of preterm labor: a systematic review and metaanalysis

OBJECTIVE

The purpose of this study was to evaluate the efficacy and safety of transdermal nitroglycerin as a tocolytic agent in women with preterm labor.

STUDY DESIGN

We conducted a systematic review and metaanalysis of randomized controlled trials.

RESULTS

Thirteen studies were included (1302 women) comparing transdermal nitroglycerin vs placebo (2 studies; n = 186); β2-adrenergic receptor agonists (9 studies; n = 1024); nifedipine (1 study; n = 50); and magnesium sulfate (1 study; n = 42). There were no significant differences between transdermal nitroglycerin and placebo for delivery within 48 hours of the initiation of treatment or at <28, <34, or <37 weeks of gestation, adverse neonatal outcomes, and neurodevelopmental status at 24 months of life. Nevertheless, 1 study found a marginally significant reduction in the risk of a composite outcome of major neonatal morbidity and perinatal death (3/74 [4.1%] vs 11/79 [13.9%]; relative risk, 0.29; 95% confidence interval, 0.08-1.00). When compared with β2-adrenergic receptor agonists, transdermal nitroglycerin was associated with a significant reduction in the risk of preterm birth at <34 and <37 weeks of gestation, admission to the neonatal intensive care unit, use of mechanical ventilation, and maternal side effects. There were no significant differences between transdermal nitroglycerin and nifedipine and magnesium sulfate in delivery within 48 hours of treatment and pregnancy prolongation, respectively. Overall, women who received transdermal nitroglycerin had a higher risk of headache.

CONCLUSION

Although transdermal nitroglycerin appears to be more effective than β2-adrenergic receptor agonists, the current evidence does not support its routine use as a tocolytic agent for the treatment of preterm labor. Further double-blind placebo-controlled trials are needed.

Nitric oxide donors for the treatment of preterm labour

BACKGROUND

A number of tocolytics have been advocated for the treatment of threatened preterm labour in order to delay delivery. The rationale is that a delay in delivery may be associated with improved neonatal morbidity or mortality. Nitric oxide donors, such as nitroglycerin, have been used to relax the uterus. This review addresses their efficacy, side effects and influence on neonatal outcome.

OBJECTIVES

To determine whether nitric oxide donors administered in threatened preterm labour are associated with a delay in delivery, adverse side effects or improved neonatal outcome.

SEARCH STRATEGY

A comprehensive search of the Cochrane Pregnancy and Childbirth Group trials register (March 2002) and the Cochrane Controlled Trials Register (The Cochrane Library, Issue 1, 2002) was undertaken.

SELECTION CRITERIA

Randomised controlled trials of nitric oxide donors administered for tocolysis.

DATA COLLECTION AND ANALYSIS

Trial quality assessment and data extraction were done independently by two reviewers.

MAIN RESULTS

Five randomised controlled trials (466 women) were included. Nitroglycerine was the NO donor used in all these trials. Nitric oxide donors did not delay delivery nor improve neonatal outcome when compared with placebo, no treatment or alternative tocolytics such as ritodrine, albuterol and magnesium sulphate. There was, however, a reduction in number of deliveries less than 37 weeks when compared with alternative tocolytics but the numbers of deliveries before 32 and 34 weeks were not influenced. Side effects (other than headache) were reduced in women who received nitric oxide donors rather than other tocolytics. However, women were significantly more likely to experience headache when NO donors had been used.

REVIEWER'S CONCLUSIONS

There is currently insufficient evidence to support the routine administration of nitric oxide donors in the treatment of threatened preterm labour.