Background In northern rural Malawi, the majority of households cook using open fires and there is also a high burden of adverse birth outcomes. The use of open fires or highly polluting cookstoves is associated with low birthweight in babies. There is mixed evidence on whether implementation of cleaner burning cookstoves reduces the number of babies born with low birthweight. Methods This is a secondary analysis of a cluster randomized control trial in Malawi, conducted over 2014–17. Households were randomized to receive improved cookstoves or to continue current practices. For this analysis, the primary outcome was low birthweight in households under routine demographic surveillance, among births occurring within the trial time frame (N = 4010). A subset of data with stricter exposure definitions respecting the original randomized allocation was also analysed (N = 1050). A causal, forwards modelling approach was used. Results The main dataset showed evidence of effect of the intervention on low birthweight [adjusted odds ratio (aOR) 0.69; 95% CI 0.48–0.99, n = 2788). The subset analysis lacked power to provide evidence of association between improved cookstoves and low birthweight in the stricter exposure definition (aOR 0.62; 95% CI 0.35–1.09, n = 932). Conclusions This study provides some evidence that an improved cookstove intervention in rural Malawi reduced the number of babies born with low birthweight by 30%. This direction of the effect was also seen in the subset analysis. The analysis suggests that the intervention reduced the number of infants born prematurely or with intra-uterine growth restriction, indicating that improved cookstoves could be a useful maternal health intervention.

中文翻译：

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整群随机对照试验的二次数据分析：改善炉灶与降低马拉维农村低出生体重发生率有关

背景 在马拉维北部农村地区，大多数家庭使用明火做饭，不良分娩后果也很严重。使用明火或高污染炉灶与婴儿低出生体重有关。关于实施更清洁的炉灶是否会减少低出生体重婴儿的数量，证据不一。方法 这是对 2014-17 年在马拉维进行的一项整群随机对照试验的二次分析。家庭被随机分配接受改进的炉灶或继续目前的做法。对于此分析，主要结果是在试验时间范围内出生的常规人口统计监测家庭中的低出生体重 (N = 4010)。还分析了关于原始随机分配的具有更严格暴露定义的数据子集 (N = 1050)。使用了因果关系、正向建模方法。结果 主要数据集显示了干预对低出生体重影响的证据 [调整后的比值比 (aOR) 0.69；95% CI 0.48–0.99，n = 2788）。在更严格的暴露定义（aOR 0.62；95% CI 0.35–1.09，n = 932）中，子集分析无法提供改良炉灶与低出生体重之间关联的证据。结论 本研究提供了一些证据，表明在马拉维农村地区改进的炉灶干预措施使低出生体重婴儿的数量减少了 30%。在子集分析中也看到了这种影响方向。