Читать книгу Neonatal Haematology - Barbara J. Bain, Irene Roberts - Страница 35

Platelets appear in the circulation at 5–6 weeks’ gestation and reach values of 150 × 10⁹/l by the end of the first trimester^110,118 and 175–250 × 10⁹/l during the second and third trimesters.^93,130,131 Although some studies have suggested that there is a linear increase in the platelet count with increasing gestational age, a large study of more than 5000 fetal blood samples showed that there was no further significant increase in fetal platelet count through the second and third trimesters.¹³¹ Thus, a platelet count of less than 150 × 10⁹/l can be considered abnormal, even in the most preterm neonate.