Association of Placental Pathology and Antibiotic Exposure after Birth with the Severity of Necrotizing Enterocolitis in Preterm Infants: A Case-Control Study.

This study aimed to assess the relationship between placental lesions, antibiotic exposure duration, and necrotizing enterocolitis (NEC) severity in preterm infants.In this single-center, case-control study, 107 infants with NEC and 130 controls were grouped by antibiotic exposure after birth: ≤3 or >3 days.Of 212 infants, 103 (48.5%) received antibiotics for ≤3 days, while 109 (51.5%) received antibiotics for >3 days. Multivariate regression analysis demonstrated that prolonged antibiotic duration (>3 vs. ≤3 days) was significantly associated with increased severity of NEC, with adjusted odds ratios (aORs) of 2.65 (95% confidence interval [CI]: 1.36-5.16; p = 0.004) for medical NEC and 3.36 (95% CI: 1.56-7.23; p = 0.002) for surgical NEC. However, prolonged antibiotic duration was not significantly associated with overall mortality (aOR = 1.16, 95% CI: 0.58-2.34; p = 0.7). Among infants diagnosed with NEC (n = 97), antibiotic duration of >3 days significantly increased the odds of mortality (aOR = 7.34, 95% CI: 1.94-48.3; p = 0.011) but was not significantly associated with NEC severity (aOR = 1.20, 95% CI: 0.49-2.94; p = 0.7). Among 64 infants with acute histologic chorioamnionitis, 37 (58%) received antibiotics for >3 days. Longer antibiotic exposure was linked to higher risks of medical NEC (79 vs. 38%; p = 0.021) and surgical NEC (62 vs. 38%; p = 0.021) compared with shorter exposure. In 134 infants with maternal vascular malperfusion (MVM), prolonged antibiotics were also associated with increased risks for medical (60 vs. 36%; p = 0.007) and surgical NEC (67 vs. 36%; p = 0.007). Concordance between clinical and pathologic chorioamnionitis was moderate (first-order agreement coefficient [AC1] = 0.60), while agreement for pregnancy-induced hypertension versus MVM was minimal (AC1 = 0.07).Prolonged antibiotic exposure (>3 days) in infants with chorioamnionitis or MVM is most likely associated with increased NEC severity. Limiting antibiotic duration may reduce severe NEC risk in preterm infants. · Prolonged antibiotics following birth are associated with NEC severity.. · Infants exposed to chorioamnionitis and receiving prolonged antibiotics are more likely at NEC risk.. · Shorter duration of antibiotics following birth may reduce NEC risk..