Perinatal outcome of idiopathic small for gestational age pregnancies at term: the effect of antenatal diagnosis

OBJECTIVE: To evaluate the effect of antenatal detection of the idiopathic term small for gestational age (SGA) fetus upon perinatal outcome. METHODS: A 3-year retrospective review of all term pregnancies with no associated maternal disease, with birth weights at least 2 S.D.s below the mean for gestational age. Perinatal outcome measures were compared between pregnancies that were diagnosed as SGA antenatally, and those that were detected only after delivery. RESULTS: Of 158 term SGA pregnancies, 47 were diagnosed antenatally, and III were recognized as such only after delivery. The antenatally diagnosed group had a higher incidence of adverse neonatal outcome (P < 0.01), as well as higher incidences of inductions of labor and emergency Cesarean sections (68% vs. 12%, P < 0.001, and 23% vs. 10%, P < 0.03, respectively). Logistic regression analysis with adverse neonatal outcome as the dependent variable has shown it to be dependent only on gestational age at delivery (P < 0.004), and birth weight (P < 0.001), and not on antenatal diagnosis. CONCLUSIONS: Antenatal detection of SGA may be associated with an increased incidence of obstetric interventions, with no demonstrable positive effect upon the short-term neonatal outcome.