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.