Doppler-inclusive reclassification of fetal growth restriction based on Japanese criterion: a single-center study on perinatal outcomes of pathological and normal small fetuses.

Purpose: Criteria for diagnosing fetal growth restriction (FGR) vary globally. The Japanese criterion is estimated fetal weight (EFW) below - 1.5 standard deviations, without distinctions based on gestational age or severity. However, some international diagnostic criteria classify FGR using gestational age, Doppler assessments, and growth. While the Japanese criterion is simple and easy to apply, including EFW, gestational age at diagnosis, growth, and Doppler findings can provide a more comprehensive assessment of fetoplacental function. The aims of this study were: [1] to reclassify small fetuses on the Japanese criterion into early FGR, late FGR, or small for gestational age (SGA) groups by applying Doppler-inclusive diagnostic criteria, and [2] compare the perinatal outcomes.

Methods: In this retrospective study, FGR diagnosed based on the Japanese criterion between 2017 and 2021 at our hospital were reclassified into early FGR, late FGR, or SGA by applying Doppler-inclusive criteria. Cases not classified as early or late FGR were categorized as SGA. Perinatal, maternal, and neonatal outcomes were analyzed across all groups.

Results: Overall, 184 growth-restricted fetuses based on the Japanese criterion-160 cases (42 early FGR, 51 late FGR, and 67 SGA)-were enrolled after excluding 24 cases of fetal malformation. Gestational age at delivery, mode of delivery, and maternal and neonatal complications differed significantly among the groups. The early FGR group showed a significantly higher incidence of preterm birth, emergent Cesarean section, and severe maternal or neonatal complications.

Conclusions: FGR with Doppler-inclusive criteria can be better for practical use providing high relevance to perinatal outcome.