19 small for gestational age (SGA) infants with gestational ages less than or equal to 32 weeks were matched with 19 appropriate for gestational age (AGA) preterm neonates with similar risk factors for intraventricular haemorrhage and hyaline membrane disease. Gestational age, 1- and 5-minute Apgar scores, type of delivery, survival rate, use of corticosteroids before delivery, sex, twinning, presence of premature rupture of membranes, and birth date were comparable in the two groups. Gestational age of both groups was 30 (+/- 1.8) weeks, and birthweights were 919 (+/- 202) g (SGA group) and 1268 (+/- 212) g (AGA group). The incidences of hyaline membrane disease and intraventricular haemorrhage were different: 74 and 42% respectively for AGA neonates, 5 and 11% respectively for SGA infants. We suggest that a stressful environment in utero may enhance maturation and prevent hyaline membrane disease and intraventricular haemorrhage.