Antimicrobials for Preterm Birth Prevention: An Overview

Objective. Preterm birth (PTB) remains a major cause of neonatal morbidity and mortality. The association between PTB and infection is clear. The purpose of this report is to present a focused review of information on the use of antibiotics to prevent PTB. Methods. We performed a search of the PubMed database restricted to clinical trials or meta-analyses published in English from 1990 through May 2011 using keywords “antibiotics or antimicrobials” and “preterm.” Results. The search yielded 67 abstracts for review. We selected 31 clinical trials (n = 26) or meta-analysis (n = 5) for further full-text review. Discussion of each eligible clinical trial, its specific inclusion criteria, antibiotic regimen used, and study results are presented. Overall, trials evaluating antibiotic treatment to prevent preterm birth have yielded mixed results regarding any benefit. Conclusion. Routine antibiotic prophylaxis is not recommended for prevention of preterm birth

Adjunctive Azithromycin Prophylaxis for Cesarean Delivery

The addition of azithromycin to standard regimens for antibiotic prophylaxis before cesarean delivery may further reduce the rate of postoperative infection. We evaluated the benefits and safety of azithromycin-based extended-spectrum prophylaxis in women undergoing nonelective cesarean section

Is low-dose aspirin therapy to prevent preeclampsia more efficacious in non-obese women or when initiated early in pregnancy?

<div><p></p><p><i>Objective</i>: Late timing of intervention and maternal obesity are potential explanations for the modest effect of aspirin for preeclampsia prevention. We explored whether low-dose aspirin (LDA) is more effective in women at increased risk when initiated before 16 weeks' gestation or given to non-obese women.</p><p><i>Methods</i>: Secondary analysis of a trial to evaluate LDA (60 mg/d) for preeclampsia prevention in high-risk women. Participants were randomized to LDA or placebo between 13 and 26 weeks. We stratified the effect of LDA on preeclampsia by (a) timing of randomization (< 16 or ≥ 16 weeks gestation) and (b) body mass index (BMI) class (non-obese and obese). The Breslow–Day test for homogeneity was used to assess for variations in effect of LDA across gestational age and BMI groups.</p><p><i>Results</i>: Of 2503 women, 461 (18.4%) initiated LDA < 16 weeks. LDA effect was not better when initiated < 16 weeks (RR: 0.93, 95% CI: 0.67–1.31) versus ≥ 16 weeks (RR: 0.90, 95% CI: 0.75–1.08), (<i>p</i> value for interaction = 0.87). Similarly, LDA effect was not better in non-obese (RR: 0.91, 95% CI: 0.7–1.13) versus obese women (RR: 0.89, 95% CI: 0.7–1.13), (<i>p</i> value for interaction = 0.85).</p><p><i>Conclusion</i>: LDA for preeclampsia prevention was not more effective when initiated < 16 weeks or used in non-obese women at risk for preeclampsia. No particular subgroup of women was more or less likely to benefit from LDA therapy.</p></div

Adjunctive Azithromycin Prophylaxis for Cesarean Delivery

BACKGROUND: The addition of azithromycin to standard regimens for antibiotic prophylaxis before cesarean delivery may further reduce the rate of postoperative infection. We evaluated the benefits and safety of azithromycin-based extended-spectrum prophylaxis in women undergoing nonelective cesarean section. METHODS: In this trial conducted at 14 centers in the United States, we studied 2013 women who had a singleton pregnancy with a gestation of 24 weeks or more and who were undergoing cesarean delivery during labor or after membrane rupture. We randomly assigned 1019 to receive 500 mg of intravenous azithromycin and 994 to receive placebo. All the women were also scheduled to receive standard antibiotic prophylaxis. The primary outcome was a composite of endometritis, wound infection, or other infection occurring within 6 weeks. RESULTS: The primary outcome occurred in 62 women (6.1%) who received azithromycin and in 119 (12.0%) who received placebo (relative risk, 0.51; 95% confidence interval [CI], 0.38 to 0.68; P<0.001). There were significant differences between the azithromycin group and the placebo group in rates of endometritis (3.8% vs. 6.1%, P = 0.02), wound infection (2.4% vs. 6.6%, P<0.001), and serious maternal adverse events (1.5% vs. 2.9%, P = 0.03). There was no significant between-group difference in a secondary neonatal composite outcome that included neonatal death and serious neonatal complications (14.3% vs. 13.6%, P = 0.63). CONCLUSIONS: Among women undergoing nonelective cesarean delivery who were all receiving standard antibiotic prophylaxis, extended-spectrum prophylaxis with adjunctive azithromycin was more effective than placebo in reducing the risk of postoperative infection. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development; C/SOAP ClinicalTrials.gov number, NCT01235546.

Maternal tobacco use modestly alters correlated epigenome-wide placental DNA methylation and gene expression

Several studies linking alterations in differential placental methylation with pregnancy disorders have implicated (de) regulation of the placental epigenome with fetal programming and later-in-life disease. We have previously demonstrated that maternal tobacco use is associated with alterations in promoter methylation of placental CYP1A1 and that these changes are correlated with CYP1A1 gene expression and fetal growth restriction. In this study we sought to expand our analysis of promoter methylation by correlating it to gene expression on a genome-wide scale. Employing side-by-side IlluminaHG-12 gene transcription with Infinium27K methylation arrays, we interrogated correlative changes in placental gene expression and DNA methylation associated with maternal tobacco smoke exposure at an epigenome-wide level and in consideration of signature gene pathways. We observed that the expression of 623 genes and the methylation of 1,024 CpG dinucleotides are significantly altered among smokers, with only 38 CpGs showing significant differential methylation (differing by a methylation level of ≥10%). We identified a significant Pearson correlation (≥0.7 or ≤-0.7) between placental transcriptional regulation and differential CpG methylation in only 25 genes among non-smokers but in 438 genes among smokers (18-fold increase, p < 0.0001), with a dominant effect among oxidative stress pathways. Differential methylation at as few as 6 sites was attributed to maternal smoking-mediated birth weight reduction in linear regression models with Bonferroni correction (p < 1.8 × 10−6). These studies suggest that a common perinatal exposure (such as maternal smoking) deregulates placental methylation in a CpG site-specific manner that correlates with meaningful alterations in gene expression along signature pathways