Objective  To assess the risk of persistent (>7 days) increases in brain parenchymal echogenicity in preterm infants and their association with known obstetric risk factors.

Design  Case–control study of prospectively collected data.

Setting  A University hospital in Northern Italy.

Population  Eighty-five singleton infants between 24 and 34 weeks of gestation with a cranial ultrasonographic diagnosis of persistently increased parenchymal echogenicity without development of cystic degeneration, and 170 control infants with negative cranial ultrasonographic findings.

Methods  A comparison of the prevalence of selected obstetric risk factors between infants with persistent echo-dense lesions and negative controls.

Main outcome measures  Odds ratios of persistent echo-dense lesions including first-degree interactions between variables.

Results  After adjusting for birthweight, logistic regression analysis showed that the only factor associated with an increased risk of persistent brain echo-dense lesions in infants was multiple courses of antenatal steroids (OR = 2.14, 95% CI = 1.11–4.15, P= 0.024). In this group, the risk of persistent echo-dense lesions was particularly high in: (i) mothers receiving dexamethasone rather than betamethasone (P value for interaction = 0.015) and (ii) after expectant management of pre-eclampsia or intrauterine growth retardation (P value for interaction = 0.03).

Conclusions  Multiple doses of antenatal steroids, especially dexamethasone, could influence the prevalence of persistent increases in brain parenchymal echogenicity in preterm infants.