Antenatal onset of haemorrhagic and/or ischaemic lesions in preterm infants: prevalence and associated obstetric variables.

AIM To assess the prevalence of an antenatal onset of haemorrhagic and/or ischaemic lesions in preterm infants; to identify possibly related obstetric risk factors. METHODS A prospective cohort study was made of 1332 infants born at less than 34 completed weeks, using cranial ultrasound, for the presence of antenatal brain lesions (group A) involving the periventricular white matter (PVWM) or central grey matter. Entry criteria were presence of (i) cysts in the PVWM < 7 days; (ii) increased PVWM echogenicity < 6 hours, confirmed to be white matter necrosis at post mortem examination; (iii) a unilateral porencephalic cyst < 3 days; (iv) an intraventricular haemorrhage with unilateral parenchymal involvement < 6 hours; and (v) symmetrical areas of increased echogenicity in the thalami, confirmed to be areas of calcification on post mortem examination. Group B consisted of infants with a normal early neonatal ultrasound scan with subsequent development of the lesions mentioned above. RESULTS Twenty four cases met the entry criteria for group A: 17 died and five of the seven survivors developed cerebral palsy at follow up. Of the whole cohort, 156 (11.7%) infants died and in 63 (40.3%) of these a large ultrasound lesion was present. In 17 (26.9%) cases this lesion was considered to be of antenatal onset. Sixty eight of the 1176 (5.8%) survivors developed cerebral palsy and this was attributed to antenatal onset in five (7.3%). A comparison of the obstetric risk factors between the infants in group A and B, who either died or developed cerebral palsy, showed a significant difference in gestational age between the two groups (30.9 vs 28.9 weeks; p < 0.001). Prolonged rupture of membranes was significantly more common in group B (p = 0.03), while an ominous cardiotachogram was significantly more common in group A (p = 0.01), and this remained significant following logistic regression analysis. CONCLUSIONS Although these data suggest that most preterm infants did not develop their brain lesions in utero, an antenatal onset was not uncommon, especially in those with PVWM lesions, who did not survive the neonatal period.