Page 169 - كتاب تمريض نسا الاكتروني

167

 Position: Maternal position affects her anatomic and physiologic

adaptations to labor. A woman in labor should be encouraged to find

positions that are most comfortable to her.

 Psychological state of the woman and her personality: knowledgeable
and relaxed woman, who is actively participating in the birth process,
usually experiences shorter, less intense labor. The process of labor also

depends on woman's pain threshold.

 Theories of Onset of Labor

1 – Prostaglandins :

* Can induce uterine contractions.

* They are formed in the decidua and membranes.

* Their level increases near term.

2 – Progesterone withdrawal:

* Progesterone supports pregnancy, it decreases the frequency of uterine
contractions . .

* A drop in progesterone level-with subsequent onset of labor could be proved only
in some animals, not in humans.

3 – Estrogen/ Progesterone:

- Estrogen helps the initiation of uterine contractions.

- Estrogen level increases near term.

4 – Estrogen-Oxytocin:

* Estrogen increases the myometrial receptors to Oxytocin “indirect effect’’.

* Oxytocin causes uterine contractions.
5 – Fetal suprarenal:

- The increase production of estrogen by the placenta near term is due to an
increase in the level its precursor: DHEAS. (dehydro- epiandrosterone sulfate)

Table of Content