Hormones Involved in Parturition Flashcards Preview

Scientific Basis of Midwifery > Hormones Involved in Parturition > Flashcards

Flashcards in Hormones Involved in Parturition Deck (18)
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When and where is cortisol produced/ secreted?

- Towards end of term pregnancy
- Production stimulated by oestrogen
- Anterior pituitary gland of foetus


Describe the action and effects of cortisol

- Reduces maternal production of progesterone
- Levels increase in response to stress, caused by increased cardiac output and decreased glucose levels (eg)
- Has a positive effect on conditions such as rheumatoid arthritis and eczema


When and where is progesterone produced/ secreted?

- Throughout pregnancy
- Stop prior to onset of labour
- Levels gradually increase at first but then more markedly after week 10
- Placenta


Describe the action and effects of progesterone

- In pregnancy, relaxes smooth muscle, increases body temp, RR and Na and Cl excretion
- Inhibits contractions
- Used for foetal synthesis of testosterone, corticosteroids and mineralcorticoids
- Miscarriages associated with decreased progesterone levels caused by stress


When and where is oestrogen produced/secreted?

- Throughout pregnancy
- Slight rise towards end
- Levels don't increase until week 9
- Ovaries and placenta


Describe the action and effects of oestrogen

- Promotes growth of endometrium and breasts
- Increases prolactin secretion
- Enhances myometrial activity
- Stimulates fluid retention
- Slight rise can make uterus more sensitive to oxytocin
- Primary oestrogen in pregnancy = oestriol
- Levels increase 100x in pregnancy


When and where are prostaglandins produced/ secreted?

- Late pregnancy
- Production can be stimulated by coitus, VE, membrane sweep, amniotomy and labour
- Not clear where produced but found in foetal membranes, decidua, myometrium and cervix


Describe the action and effects of prostaglandins

Important for the progress of labour


When and where is oxytocin produced/ secreted?

- During labour
- Maternal posterior pituitary gland and foetal pituitary gland in labour


Describe the action and effect of oxytocin

Necessary for effective progress of labour and stimulating the uterus to contract


When and where is relaxin produced/ secreted?

- Throughout pregnancy
- Levels highest in 1st trimester
- Corpus luteum, myometrium and placenta


Describe the action and effect of relaxin

- Acts with progesterone to inhibit myometrial contractility (maintains uterine quiescence)
- Softens pelvic ligaments
- Promotes cervical ripening just before onset of labour
- Associated with endometrial differentiation during embryo implantation and wound healing


When and where is hCG produced/ secreted?

- Early pregnancy
- Max. production = 8-10 weeks
- Trophoblast cells


Describe the action and effect of hCG

- Maintains production of steroid hormones from corpus luteum until placenta takes over
- Acts on LH receptors to prolong life of corpus luteum
- Indicates pregnancy (measureable levels 2 weeks after conception)
- Persistently low levels associated with abnormal placental development/ ectopic pregnancy
- May be responsible for nausea and vomiting


When and where is hPL produced/ secreted?

- Late pregnancy
- Syncytiotrophoblast cells


Describe the action and effect of hPL

- As hCG levels decrease, hPL levels increase
- Levels correlate with foetal and placental weight
- Stimulates growth of maternal and foetal tissue
- Protects foetus from rejection
- Low levels associated with pregnancy failure and spontaneous abortion
- Increases maternal metabolism and utilisation of fat as an energy substrate


When and where is prolactin produced/ secreted?

- Levels increase throughout pregnancy
- Anterior pituitary gland


Describe the action and effects of prolactin

- Increased oestrogen and progesterone levels in pregnancy cause number of prolactin-secreting cells to increase from 10% to 50%
- Stimulates lactation