Effect of delivery mode on postnatal platelet count dynamics in neonates born to mothers with immune thrombocytopenia.

We aimed to determine the effect of delivery mode on postnatal platelet count dynamics in neonates born to mothers with immune thrombocytopenia (ITP). This single-center, retrospective study included 41 mothers with ITP and their 65 infants born by vaginal delivery (VD, n = 30) and cesarean section (CS, n = 35) between January 1997 and March 2022. The median difference in platelet counts from day 0 to day 2 (ΔPlt [D 0-2]) was significantly lower in the VD group (- 39 × 10 9 /L, interquartile range [IQR]: - 47 to - 24 × 10 9 /L) than the CS group (15 × 10 9 /L, IQR: - 6.5 to 33 × 10 9 /L) (p < 0.001). The median ΔPlt (D 0-5) was significantly lower in the VD group (- 55 × 10 9 /L, IQR: - 85 to - 31 × 10 9 /L) than the CS group (33 × 10 9 /L, IQR: 1-69 × 10 9 /L) (p < 0.001). Multivariate analysis also showed a significant association of delivery mode with ΔPlt (D 0-2) and ΔPlt (D 0-5) (both p < 0.001). VD neonates with platelet counts ≥ 100 × 10 9 /L at birth were significantly more likely than CS neonates to develop thrombocytopenia < 100 × 10 9 /L at nadir (1/26 vs. 6/25) (p = 0.0496). Our findings indicate that mode of delivery is a useful predictor of postnatal platelet count dynamics in neonates born to mothers with ITP.