A systematic review with meta-analysis on the effects of maternal exposure to natural disasters on human birth outcomes

Natural disasters have generally been associated with an increase in adverse birth outcomes, including preterm birth (PTB) and low birthweight (LBW) – two key markers of infant health that are predictive of infant mortality and life-long medical disabilities. However, there is considerable inconsistency between studies which makes it difficult to inform policy on pregnancy during and after natural disasters. In this study, we identify risk factors for pregnant women by undertaking the first meta-analysis on this topic, synthesising data from 42 studies with over 24 million participants. We also perform sub-group analysis on disaster type, a country's economic development, and trimester of exposure, addressing associations that can often not be examined in single studies. We found natural disasters to be associated with increased odds of both LBW (OR = 1.063) and PTB (OR = 1.075), with the largest effects seen from exposure in low Human Development Index countries (LBW: OR = 1.130; PTB: OR = 1.315), in first trimester (LBW: OR = 1.079; PTB: OR = 1.153), and following earthquake exposure for PTB (OR = 1.154). Our findings highlight the importance of directing disaster recovery efforts towards these vulnerable groups, to minimise the impacts on infant health following natural disasters.