At the end of the first trimester, what hormone contributes to the reduction of lower esophageal sphincter tone, increasing the risk for aspiration?

The hormone that contributes to the reduction of lower esophageal sphincter tone at the end of the first trimester is progesterone. During pregnancy, progesterone plays a crucial role in maintaining the pregnancy and facilitating physiological changes in the body. One of these changes includes the relaxation of smooth muscles, which encompasses the lower esophageal sphincter. This relaxation can lead to decreased tone in the sphincter, which may result in gastroesophageal reflux and increased risk for aspiration, particularly as the pregnancy progresses.

Progesterone's action on the smooth muscles is significant because it allows for the necessary expansion of the uterus and other organs to accommodate the developing fetus. However, this also means that the protective mechanism of the lower esophageal sphincter is compromised, raising concern for aspiration, particularly in the context of anesthesia and critical care management. Understanding these hormonal influences is essential for anticipating complications in pregnant patients and providing appropriate care.