Thavagnanam S, Fleming J, Bromley A, Shields M D, Cardwell C R
Royal Belfast Hospital for Sick Children, Belfast, Northern Ireland.
Clin Exp Allergy. 2008 Apr;38(4):629-33. doi: 10.1111/j.1365-2222.2007.02780.x.
Children born by Caesarean section have modified intestinal bacterial colonization and consequently may have an increased risk of developing asthma under the hygiene hypothesis. The results of previous studies that have investigated the association between Caesarean section and asthma have been conflicting.
To review published literature and perform a meta-analysis summarizing the evidence in support of an association between children born by Caesarean section and asthma.
MEDLINE, Web Science, Google Scholar and PubMed were searched to identify relevant studies. Odds ratio (OR) and 95% confidence interval (CI) were calculated for each study from the reported prevalence of asthma in children born by Caesarean section and in control children. Meta-analysis was then used to derive a combined OR and test for heterogeneity in the findings between studies.
Twenty-three studies were identified. The overall meta-analysis revealed an increase in the risk of asthma in children delivered by Caesarean section (OR=1.22, 95% CI 1.14, 1.29). However, in this analysis, there was evidence of heterogeneity (I(2)=46%) that was statistically significant (P<0.001). Restricting the analysis to childhood studies, this heterogeneity was markedly decreased (I(2)=32%) and no longer attained statistical significance (P=0.08). In these studies, there was also evidence of an increase (P<0.001) in the risk of asthma after Caesarean section (OR=1.20, 95% CI 1.14, 12.6).
In this meta-analysis, we found a 20% increase in the subsequent risk of asthma in children who had been delivered by Caesarean section.
剖宫产出生的儿童肠道细菌定植情况有所改变，因此根据卫生假说，其患哮喘的风险可能会增加。以往研究剖宫产与哮喘之间关联的结果相互矛盾。
回顾已发表的文献，并进行荟萃分析，总结支持剖宫产出生儿童与哮喘之间存在关联的证据。
检索MEDLINE、Web Science、谷歌学术和PubMed以识别相关研究。根据报道的剖宫产出生儿童和对照儿童哮喘患病率，为每项研究计算比值比（OR）和95%置信区间（CI）。然后使用荟萃分析得出合并的OR，并检验各研究结果之间的异质性。
共识别出23项研究。总体荟萃分析显示，剖宫产出生儿童患哮喘的风险增加（OR = 1.22，95% CI 1.14，1.29）。然而，在该分析中，有证据表明存在异质性（I² = 46%），且具有统计学意义（P < 0.001）。将分析局限于儿童期研究时，这种异质性显著降低（I² = 32%），且不再具有统计学意义（P = 0.08）。在这些研究中，也有证据表明剖宫产术后哮喘风险增加（P < 0.001）（OR = 1.20，95% CI 1.14，12.6）。
在这项荟萃分析中，我们发现剖宫产出生儿童随后患哮喘的风险增加了20%。
