Surfactant protein A

Surfactant protein A is an innate immune system collectin.

During Parturition
The role of Surfactant protein A (or SP-A) in childbirth is indicated in studies with mice. Mice which gestate for 19 days typically show signs of SP-A in amniotic fluid at around 16 days. If SP-A is injected into the uterus at 15 days, mice typically deliver early. Inversely, an SP-A inhibitor injection causes notable delays in birth.

The presence of Surfactant Protein A seemed to trigger an inflammatory response in the uterus of the mice, but later studies found an anti-inflammatory response in humans. In fact, the level of SP-A in a human uterus typically decreases during labor.