Characterization of Neonatal Clinical Risk Profiles in Relation to Prenatal Obstetric Characteristics in Infants With Early-FGR Secondary to Doppler Flowmetry Alterations

Plain-language summary

This study aims to characterize neonatal clinical risk profiles in relation to prenatal obstetric characteristics in infants with early fetal growth restriction (early-FGR) secondary to Doppler flowmetry alterations. The primary objective is to analyze the association between maternal and obstetric factors-such as preeclampsia, diabetes, and the timing and progression of Doppler changes-and neonatal clinical outcomes. The research evaluates how these relationships vary based on the prenatal flowmetric profile (umbilical artery \[UA\] with absent end-diastolic flow \[UA bs-\], UA with reversed end-diastolic flow \[UA bs+\], or UA alterations combined with ductus venosus \[DV\] changes) compared to preterm infants without FGR. Conducted as a spontaneous, multicenter, observational study with both retrospective and prospective components, the research involves mothers and their preterm neonates. The study population includes cases defined as neonates with a gestational age of 32 weeks or less and/or a birth weight under 1500 grams, with a prenatal history positive for FGR (fetal weight or abdominal circumference/fetal weight ratio below the 10th percentile) and documented fetal or utero-placental Doppler alterations. The control group consists of neonates within the same gestational age or weight criteria but without evidence of FGR or flowmetric alterations. Exclusion criteria apply to fetuses with known or suspected malformations or genetic anomalies, cases involving maternal substance abuse during pregnancy, and multiple pregnancies. With a total duration of 30 months, including 12 months for enrollment and 6 months for data analysis, the study targets a sample size of 850 subjects, comprising approximately 600 controls and 200 FGR cases. The statistical analysis will focus on pre-specified outcomes to assess the associations between maternal/obstetric factors and neonatal health, stratified by Doppler profile. Continuous variables will be summarized as mean and standard deviation or median and interquartile range, while categorical variables will be expressed as absolute frequencies and percentages. Group comparisons will utilize parametric or non-parametric tests based on data distribution. The main analysis will employ logistic regression models for binary outcomes and linear regression models for continuous outcomes, utilizing clustered standard errors by center to account for the multicenter design. Candidate covariates include gestational age, sex, and key maternal conditions such as preeclampsia, diabetes, pathological cardiotocography (CTG), and the timing of Doppler changes. To manage a high number of predictors relative to the sample size, penalization techniques such as lasso or elastic net will be applied for automatic covariate reduction and estimation stabilization. Subsequent analyses, including interaction models, will focus on the covariates selected through these procedures to provide a comprehensive understanding of how prenatal hemodynamic compromises influence the clinical trajectory of the preterm neonate.

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