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Perinatal exposure | Effect on gut microbiota | Effect on asthma development |
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Caesarean delivery | Prevents exposure to maternal fecal microbes. ↓ Bifidobacteria and Bacteroides [57, 58], ↑ C. difficile [53, 56]. Differences may persist for years [58–61]. | Increases risk of asthma [62]; recent studies inconsistent [53, 63, 64]. |
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Breastfeeding | Confers beneficial gut microbiota through prebiotic properties [66] or direct transfer of bacteria [67, 68]. ↑ Bifidobacteria, ↓C. difficile [56, 57, 65]. | Protects against asthma [69–73], except when mother is atopic [43, 44]. |
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Antibiotics | Suppresses commensal bacteria, permits emergence of C. difficile [22, 56, 77]. Disturbance may persist for years [78, 79]. Even indirect exposure is harmful [57]. | Increases risk of asthma [80–83], except when parents are atopic [82, 88]. Even indirect exposure is harmful [55, 84–87]. Some studies may be confounded [91, 92]. |
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Probiotics | Direct or indirect exposure beneficially influences gut microbiota composition [94–96]. | Protects against asthma in animal studies [97, 98]; human trials inconclusive [100–103]. |
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Perinatal stress | Causes transient and long-lasting changes to gut microbiota in animal studies [104–107]. | Increases risk of asthma [114, 115]. |
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