Uteroglobin binds progesterone specifically and with high affinity. It may regulate progesterone concentrations reaching the blastocyst. It is also a potent inhibitor of phospholipase A2. Antiparallel homodimer; disulfide-linked (PubMed:2704039, PubMed:3656405). Interaction with LMBR1L is controversial. Synthesized in the uterus and lung. By progesterone. Belongs to the secretoglobin family.