Strength and limitations
The strength of this study is that this birth dataset is the most extensive compilation to date from Latin America, including data from four countries and more than 67,000 births. In addition to the increased data quantity, we simultaneously evaluated the two current prescriptive international fetal growth standards to adjust the risk estimation of adverse perinatal outcomes and anthropometric measures associated with FGR. Differences in maternal age and antenatal care across countries might be due to population characteristics, culture, and obstetric practice. However, non-black Hispanics are currently used to agglomerate the Latin American population worldwide, so we did not consider ethnic differences within our population. Study limitations include the retrospective nature of this study. Another limitation of our study is that we only reported APGAR scores. However, this is an objective measure used to identify babies with a high risk of perinatal morbidity and poor neurological development. In addition, stillbirths were excluded because of uncertainty regarding their classification as SGA by birth weight. Other large series have shown that IG21st standards miss a fraction of babies at risk for this complex event (62). It is also a limitation of our study that we could not compare the performance of customized standards due to the lack of published and validated coefficients for all the participating countries. Although customized curves have been proposed (63–65), their superiority in identifying adverse perinatal outcomes has not been supported by more recent literature (66,67). Finally, although WHO detected a significantly higher proportion of SGA fetuses, this fraction of small fetuses likely contains instances of adverse outcomes that the data available (only Apgar) could not reveal.