CXCR4 and infection: This function of the CXCR4–CXCL12 axis plays a prominent role in the recruitment of bone marrow‐derived progenitors to the uterus and endometrium.21, 72, 73 It is also operative in the repair and regeneration of multiple non‐reproductive tissues after damage.74, 75, 76, 77 While CXCL12 is essential in activating inflammatory pathways that lead to PTL, CXCL12 also activates an accompanying repair mechanism; the later involves recruitment of progenitors to repair damage after infection or other insult.