KIT and amenorrhea: We observed that the number of IFI30+ cells mirrored the number of hematopoietic progenitors (CD117+), and that both subsets peaked between 12 and 14 gestational weeks (i.e. between 14 and 16 weeks of amenorrhea) (Fig. 7a, b), during which the hematopoietic activity of the human fetal liver also peaks38.