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.