652: Impact of mode of delivery on neonatal microbial millieu

Abstract

Mode of delivery has been linked to differences in neonatal microbiota. Given the potential role of the microbiome in neonatal and childhood health, we sought to evaluate whether mode of delivery (MOD) was associated with the bacterial profile in neonates as determined by blood culture. This is a secondary analysis of a multicenter trial evaluating magnesium for fetal neuroprotection in pregnancies at high risk for preterm delivery. We included singleton, non-anomalous, live-born gestations with blood cultures drawn at birth. The primary exposure was MOD. The primary outcome was positive neonatal blood cultures. Latency antibiotics were defined as receipt of ampicillin and erythromycin. Secondary outcomes included neonatal sepsis and microorganisms cultured. Multivariable regression models were used to assess factors related to positive blood cultures and gram-negative aerobes. Of 1804 included subjects, 671 (37.2%) delivered by cesarean (CD), 1133 (62.8%) delivered vaginally (VD), and 294 (16.3%) had positive blood cultures. Mean gestational age at delivery was 29.2 +/-2.8 weeks vs. 29.7 +/-2.7 in the CD and VD groups, respectively (p<0.01). Neonates born by CD were more likely to have positive blood cultures (19.4% vs. 14.5%, p < 0.01) and sepsis (20.7% vs. 16.1%, p=0.01). The most common organism among both CD and VD was coagulase negative Staphylococcus. Adjusting for confounders, CD remained an independent risk factor for positive blood cultures (aOR 1.43, 95% CI 1.06-1.93) (Table 2), even when stratifying by chorioamnionitis. Administration of latency antibiotics was protective (aOR 0.29, 95% CI 0.16-0.53). Notably, CDs were associated with a lower odds of gram negative aerobe colonization (aOR = 0.47, 95% CI 0.25-0.92). CD was associated with an increased risk of positive neonatal blood cultures compared to VD. These findings suggest that MOD may modulate the microbial profile in neonates, and given the potential role of the microbiome in development of obesity, asthma, and allergies, may have longstanding impacts on child health. Further study is needed to understand if these changes persist beyond the newborn period.View Large Image Figure ViewerDownload Hi-res image Download (PPT)