Using antibiotics to reduce infection in babies exposed to meconium

What is the issue?

ln about 1 out of every 10 pregnancies, babies are exposed to meconium during delivery. Meconium is the baby's first stool. If the baby passes stool before birth, stool containing amniotic fluid can enter the baby's lungs and may cause breathing difficulty while putting the baby at risk for infection and inflammation in the lungs and body.

Why is this important?

Infection/inflammation of the lungs can lead to difficulty breathing, reduced oxygen levels, and pneumonia. Antibiotics have been used to prevent infection in babies exposed to meconium during delivery.

What evidence did we find?

We searched the medical literature for eligible studies through June 2016. We found four studies that compared antibiotics versus placebo for reducing infection among babies born with meconium-stained amniotic fluid. Two studies were of good quality, and two studies were missing some details regarding study methods. These four studies included 695 babies, who were given various antibiotics or were placed in the control group (no antibiotics). Researchers evaluated several different antibiotic types and treatment lengths. Overall, we found no differences in rate of infection or death between the two groups. We graded the evidence as low quality owing to a poor quality study design and the small number of included babies.

What does this mean?

We are uncertain as to whether antibiotics have an important effect on infection in babies exposed to meconium-stained amniotic fluid. Our results are imprecise, and more studies are needed to determine the role of antibiotics in this situation.

Authors' conclusions: 

Upon review of available evidence, we found no differences in infection rates following antibiotic treatment among neonates born through meconium-stained fluid and those with meconium aspiration syndrome. The overall quality of evidence is low owing to the small number of included studies. Well-controlled studies of adequate power are needed.

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Background: 

Approximately 1 in 10 pregnancies is affected by meconium passage at delivery, which can result in meconium aspiration syndrome (MAS). MAS can cause respiratory complications and, very rarely, death. Antibiotics have been prescribed for neonates exposed to meconium in amniotic fluid, with the intention of preventing infection due to potential bacterial contaminants.

Objectives: 

We conducted this review to assess the efficacy and safety of antibiotics for:

1. prevention of infection, morbidity, and mortality among infants born through meconium-stained amniotic fluid (MSAF) who are asymptomatic at birth; and

2. prevention of infection, morbidity, and mortality among infants born through MSAF who have signs and symptoms compatible with meconium aspiration syndrome (MAS).

Search strategy: 

We performed a literature search using the following databases: MEDLINE (1966 to July 2016); Embase (1980 to July 2016); the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to July 2016); and the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 7) in the Cochrane Library. We also searched clinical trials databases, conference proceedings, and reference lists of retrieved articles.

Selection criteria: 

We included randomised and quasi-randomised controlled trials that compared antibiotics administered via any route versus placebo or no treatment for prevention of infection among neonates exposed to MSAF, or who developed MAS. We excluded cohort, case control, and any other non-randomised studies and applied no language restrictions. We included studies of term and preterm infants, and we included studies examining use of any antibacterial antibiotics. We included studies that reported on any outcomes of interest.

Data collection and analysis: 

We assessed the methodological quality of included trials by reviewing information provided in study reports and obtained by personal communication with study authors. We extracted data on relevant outcomes, estimated effect size, and reported values as risk ratios (RRs), risk differences (RDs), and mean differences (MDs), as appropriate. We conducted subgroup analyses for treatment of MAS and for prophylaxis (asymptomatic neonates exposed to meconium).

Main results: 

Four randomised controlled studies including a total of 695 participants were eligible for inclusion. Three studies evaluated neonates with MAS, and one study assessed asymptomatic neonates exposed to meconium in amniotic fluid. These studies exhibited varying degrees of methodological rigour: Two studies were at low risk of bias, and two were at unclear risk. We graded evidence derived from these studies as low quality. We downgraded overall evidence owing to the large number of participants lost to follow-up in one trial, the small sample sizes of all trials, and unclear methodological details provided for two trials.

The primary outcome was risk of early- and late-onset neonatal sepsis. Antibiotics did not decrease the risk of sepsis in neonates with a diagnosis of MAS (RR 1.54, 95% confidence interval (CI) 0.27 to 8.96; RD 0.00, 95% CI -0.02 to 0.03; 445 participants, three studies; I² = 0%) nor in asymptomatic neonates exposed to meconium in amniotic fluid (RR 0.76, 95% CI 0.25 to 2.34; RD -0.01, 95% CI -0.07 to 0.04; 250 participants, one study; I² = 0%). Results show no significant differences in mortality or duration of stay in hospital between groups given antibiotics and control groups of symptomatic and asymptomatic neonates. One study in asymptomatic neonates reported a significant reduction in duration of mechanical ventilation for the control group compared with the antibiotic group (MD 0.26, 95% CI 0.15 to 0.37; 250 participants, one study; I² = 0%).

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