AbstractBackgroundPost‐term pregnancy, defined as reaching or exceeding 42 + 0 weeks of gestation, is known to be associated with unfavourable birth outcomes. High‐income countries have responded to this risk by widely adopting labour induction protocols in late‐term, but many low‐ and middle‐income countries have not. However, understanding underlying mechanisms linking post‐term births to adverse newborn and infant outcomes remains limited.ObjectiveTo investigate the (a) prevalence of post‐term, (b) the risk factors associated with post‐term (c) the association between post‐term births and the risk of small‐for‐gestational‐age (SGA) neonates and of infant mortality in middle‐income settings.MethodsWe used existing electronic datasets from the general population of Brazil, Mexico, and Palestinian refugees. Regression models were used to explore the associations between post‐term birth and SGA and infant mortality.ResultsWe analysed 21,335,033 live births in Brazil (2011–2018), 23,416,126 in Mexico (2008–2019), and 966,102 in Palestinian refugees (2010–2020) (N = 45,717,261). Post‐term deliveries accounted for 3.1% of births in Brazil, 1.2% in Mexico, and 2.1% in Palestinian refugees. Post‐term births had approximately three times the risk of resulting in SGA neonates compared to term births. Additionally, post‐term neonates exhibited a 15% to 40% increased risk of infant mortality compared to term infants. Notably, post‐term SGA neonates faced a significantly increased risk of infant mortality compared to term appropriate for gestational age neonates.ConclusionsThese findings emphasise the critical significance of implementing induction strategies to prevent post‐term pregnancies and mitigate the associated risks of SGA neonates and subsequent infant mortality. Moreover, the study highlights the importance of accurately determining gestational age and using INTERGROWTH‐21st charts to improve the identification of SGA cases, enabling targeted interventions. This is especially relevant because post‐term SGA neonates may not exhibit low birthweight (a commonly used risk marker) and, therefore, may miss out on required specialised attention.
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