The aim of this paper is to determine whether antenatal detection of small-for-gestational-age (SGA) babies influences 2-year outcomes. All low-birth-weight (<2,500g) infants born in South-EastThames region, England from September 1, 1992 to August 31, 1993 were identified at birth. Antenatal "suspicion" and ultrasound assessment confirming growth restriction was categorized as "detection" of SGA. Postnatally, infants were classified as SGA if they had a birth weight for given gestation below the 10th centile. At 2 years, those below 32 weeks' gestation and a random 25% sample of infants of 32 weeks' gestation or more underwent pediatric assessments. Of 49,787 births, 3,456 (6.9%) were of low birth weight. One thousand four hundred and fifty one (42.5%) were SGA, of whom 611 (42%) were detected antenatally by ultrasound scan. At 2 years, 1,008 (75.8%) of 1,358 expected infants were assessed, 379 (37.6%) were SGA at birth, and 188 (49.6%) were confirmed antenatally. Although undetected infants had higher mean birth weights and gestational ages, they had a higher proportion of perinatal deaths (12.6 vs. 6.4%, RR 1.96: CI 1.32-2.86) than detected infants. At 2 years, detected SGA infants had smaller head circumferences (p = 0.026), a higher prevalence of febrile convulsions (8.0 vs. 3.1 %: p = 0.040) and lower scores on the locomotor (DQA) scale of Griffith's developmental test (p = 0.021) compared with undetected SGA infants. Despite detected SGA fetuses having lower weights and gestation at birth than undetected fetuses, they had significantly lower mortality without a parallel increase in severe 2-year neuro-developmental, clinical, or growth morbidity.