Are babies of normal birth weight who fail to reach their growth potential as diagnosed by ultrasound at increased risk?

The objectives of this study were to identify, by means of two third-trimester scans, fetuses with ultrasound evidence of inadequate growth but who were born with birth weights above the 10th centile for gestational age; and to determine if these infants constitute a high-risk group by comparing the incidence of obstetric intervention, of intrapartum complications and of neonatal morbidity between this group and the group of infants who showed no ultrasound evidence of intrauterine growth restraint. A total of 285 women with singleton pregnancies who were referred for a third-trimester ultrasound examination were included in this prospective study. Fetal weight was estimated by ultrasound twice in the third trimester and at each examination was assigned a centile score. A fall of > 20 centiles was taken as evidence of inadequate growth. The outcomes measured were the incidence of abnormal umbilical artery Doppler, induction of labor, meconiumstaining of the liquor, intrapartum fetal blood sampling, operative vaginal delivery, Cesarean section, Apgar score of < 7 at 5 min and admission to the neonatal intensive care unit. Seventy-five patients showed a drop of > 20 centiles between the first and second scans. The incidence of admission to the neonatal intensive care unit was greater in those infants who had ultrasound evidence of growth restraint. We conclude that infants of normal birth weight with inadequate growth diagnosed on ultrasound are not at increased risk, they have an increased incidence of admission to the neonatal intensive care unit, and they are more commonly found in mothers with diabetes mellitus.