Which of the following is not an important step in the event of parturition ?

Options

A. High levels of estrogen , prostaglandins and oxytocin cause the smooth muscles of the uterus to contract.
B. The estrogen/ Progesterone ratio increase .
C. Increase in oxytocin levels due to the positive feedback effect.
D. Release of prolactin.

Answer

To solve the question regarding which of the following is not an important step in the event of parturition, we will analyze each option provided:

1. **High levels of estrogen, prostaglandins, and oxytocin cause the smooth muscles of the uterus to contract.**
- This statement is true. During parturition, the levels of estrogen increase, which stimulates the production of prostaglandins and oxytocin. These hormones work together to cause the smooth muscles of the uterus to contract, facilitating childbirth.

2. **Estrogen progesterone ratio increases.**
- This statement is also true. As parturition approaches, the levels of estrogen rise while progesterone levels decrease, leading to an increased ratio of estrogen to progesterone. This change is crucial for initiating labor.

3. **Increase in oxytocin levels due to the positive feedback effect.**
- This statement is true as well. Oxytocin is released from the posterior pituitary gland and promotes uterine contractions. The contractions stimulate further release of oxytocin, creating a positive feedback loop that enhances the labor process.

4. **Release of prolactin.**
- This statement is not true in the context of parturition. Prolactin is primarily involved in milk production and lactation, not in the process of childbirth itself. Therefore, while prolactin is important for breastfeeding, it does not play a significant role during parturition.

Based on the analysis, the correct answer to the question is:

**D. Release of prolactin.**