Introduction
Small-for-gestational-age (SGA) neonates are at increased risk of mortality and several morbidities (1,2), suboptimal neurodevelopment (3–7), and susceptibility to cardiovascular disease later in life (8–10). Unrecognized SGA fetuses are at increased risk of perinatal death compared with those who are appropriately followed and managed (11). Its opportune identification allows timely interventions to reduce the risk of adverse perinatal outcomes (APOs) (12–15). Current guidelines recommend the 10th percentile as a cutoff to define SGA and the 3rd percentile to define fetal growth restriction (FGR) (16–18) since several studies have demonstrated an increased risk of perinatal morbidity and mortality beyond these cutoffs (17–23). However, there is disagreement on which charts should be used (16–21,24,25).
Two international standards for fetal growth have been constructed and published as a global effort to reduce the reported variability and the worldwide discrepancy when defining fetal growth restriction. First, the INTERGROWTH-21st (IG-21st) project reported fetal biometry standards constructed with 20,486 low-risk pregnancies delivered between 33 and 42 weeks (26–29). Using a similar concept and methodology, the World Health Organization (WHO) multicenter growth reference study proposed an alternative standard (30). However, previous studies evaluating the diagnostic performance of these fetal growth standards in different populations have reported conflicting results, preventing their worldwide adoption and implementation (31–37).
Latin America represent one of the most unequal regions globally regarding maternal and perinatal health (38–41). The region demonstrates an excess in stillbirths with an estimated rate of 8.2 stillbirths per 1000 births (95% CI 7.5-9.2) (42–44) and approximately, 60% of deaths before the age of five years old in the region occur during the first year of life, with 50% of those during the first 28 days (45). Potential differences in diagnosis of SGA among physicians in Latin America region can exacerbate an inappropriate use of the limited health resources, disadvantaging outcomes of SGA infants. At present, no studies have been performed comparing the performance of both standards to identify SGA neonates in Latin America. Therefore, the objectives of this study were to evaluate the diagnostic performance of INTERGROWTH-21st and WHO fetal growth charts to identify SGA and FGR neonates and to assess the specific risks of adverse perinatal outcomes of SGA and FGR neonates identified by each fetal growth chart in a large cohort of deliveries from Latin America.