Factors Influencing Uterine Contractility
Uterine contractility is essential during labor and delivery, influenced by various hormones. Among the listed factors, one stands out as an exception.

1. Estrogen
- Estrogen plays a critical role in enhancing uterine contractility, especially during the late stages of pregnancy.
- It increases the number and sensitivity of oxytocin receptors in the uterus, preparing it for contractions.

2. Progesterone
- Progesterone is the exception in this context.
- It generally inhibits uterine contractility by maintaining the uterine muscle in a relaxed state during most of the pregnancy.
- This hormone is crucial for preventing premature labor, allowing the fetus to develop.

3. Prostaglandins
- Prostaglandins are lipid compounds that significantly promote uterine contractions.
- They initiate labor by softening the cervix and stimulating rhythmic contractions of the myometrium.

4. Oxytocin
- Oxytocin is a powerful hormone that stimulates uterine contractions during labor.
- It is released from the posterior pituitary and increases in response to cervical stretch and contractions.

Conclusion
- In summary, while estrogen, prostaglandins, and oxytocin enhance uterine contractility, **progesterone** acts as an inhibitor, making it the correct answer to the question. Understanding these hormonal influences is crucial for comprehending the processes of labor and delivery.