Risk factors for intracranial hemorrhage among full-term infants: a case-control study.

Objective: To investigate the cause of intracranial hemorrhage among full-term infants.

Methods: A retrospective, hospital-based, matched case-control study was conducted at London Health Sciences Center, in southwestern Ontario, for the period from January 1, 1985, to December 31, 1996. Cases were diagnosed with magnetic resonance imaging, computed tomography, or ultrasonography within 7 days after birth. Control subjects were matched with respect to year of birth, sex, and, for nontransferred case patients only, obstetrician.

Results: Sixty-six full-term infants with intracranial hemorrhage were identified, and 104 control subjects were matched. Each factor was independently associated with increased risk of intracranial hemorrhage, as follows: forceps assistance (odds ratio [OR], 4.3; 95% confidence interval [CI], 1.2-15.1), compared with spontaneous vaginal delivery; 1-minute Apgar scores of 1 through 4 (OR, 110; 95% CI, 5.0-2400) and 5 through 8 (OR, 4.9; 95% CI, 1.3-18.3), compared with scores of 9 or 10 (corresponding 5-min Apgar scores were also statistically significant); and requirements for resuscitation (OR, 5.1; 95% CI, 1.8-14.1), compared with no resuscitation requirements. Of the 52 case patients for whom platelet counts were recorded within 48 hours after birth, 30.8% (95% CI, 18.3-43.3%) exhibited counts of less than 70 x 10(9)/L. Platelet counts of less than 50 x 10(9)/L were specifically associated with intraparenchymal hemorrhage and a more severe radiological grade. Forceps-associated hemorrhage was more frequently subarachnoid and subdural and less frequently intraparenchymal. Such hemorrhage also tended to be more caudal in location.

Conclusion: Thrombocytopenia seems to be an important cause of intraparenchymal hemorrhage, and the use of forceps is more likely to be associated with subarachnoid and subdural hemorrhage.