Most major bleeds in preterm infants occur in the absence of severe thrombocytopenia: an observational cohort study.

Objective: To describe the incidence of major bleeds according to different platelet counts in very preterm infants, and to explore whether this association is influenced by other risk factors for bleeding.

Design: Observational cohort study.

Setting: A Dutch tertiary care neonatal intensive care unit.

Patients: All consecutive infants with a gestational age at birth <32 weeks admitted between January 2004 and July 2022.

Exposure: Infants were stratified into nine groups based on their nadir platelet count (×10⁹/L) during admission (<10, 10-24, 25-49, 50-99, 100-149, 150-199, 200-249, 250-299 and ≥300), measured before the diagnosis of a major bleed and before any platelet transfusion was administered.

Main outcome measure: Incidence of major bleeds during admission. Logistic regression analysis was used to quantify the relationship between nadir platelet count and incidence of major bleeds.

Results: Among 2772 included infants, 224 (8%) developed a major bleed. Of the infants with a major bleed, 92% (206/224) had a nadir platelet count ≥50×10⁹/L. The incidence of major bleeds was 8% among infants with and without severe thrombocytopenia (platelet count <50×10⁹/L), 18/231 (95% CI 5 to 12) and 206/2541 (95% CI 7 to 9), respectively. Similarly, after adjustment for measured confounders, there was no notable association between nadir platelet counts below versus above 50×10⁹/L and the occurrence of major bleeds (OR 1.09, 95% CI 0.61 to 1.94).

Conclusion: In very preterm infants, the vast majority of major bleeds occur in infants without severe thrombocytopenia.