Flashcards in PREGNANCY Deck (43)
what produces human chorionic gonadotropin (hCG) and when is it produced?
produced by trophoblasts when they begin endometrial invasion
what are the effects of hCG?
- maintenance of the corpus luteum
- stimulation of oestrogen and progesterone production
- this prevents menstruation
when does hCG production peak?
at 60 - 80 days after the last menstruation
it then rapidly decreases but maintains a low concentration until the end of pregnancy
what is the effect of hCG levels decreasing?
the placenta increases secretion of oestrogen and progesterone
which hormone is detected on pregnancy tests?
where is prolactin produced?
it comes from the anterior pituitary
when is prolactin produced?
levels increase at the end of pregnancy when oestrogen and progesterone decrease
what is the role of prolactin?
it is involved in milk production and prevention of ovulation
the release is controlled by suckling
where is relaxin produced and when is it released?
it is produced by the ovaries and placenta
the levels increase in early pregancy
what is the role of relaxin?
it limits uterine activity
softens the cervix
ripens the cervix
when and where is oxytocin produced?
it comes from the posterior pituitary
it is secreted throughout pregnancy but levels increase towards the end of pregnancy
what is the role of oxytocin?
it stimulates uterine contractions
it triggers caring behaviours
what are the 2 different types of prostaglandin involved in pregnancy?
PGF2a = most abundant
PGE2 = 10 x stronger
where is prostaglandin produced and what is it's role?
produced by uterine tissue
it initiates labour
where is oestrogen and progesterone produced?
by corpus luteum
it regresses after 3 months and the placenta continues to produce oestrogen and progesterone
how does the placenta produce oestrogen and progesterone?
- placenta has enzyme capable of producing progesterone
- placenta contains aromatase which converts androgens to oestrogen
where do androgens for oestrogen come from?
- maternal ovaries
- maternal adrenal medulla
- foetal adrenal medulla
how are ovarian cycles inhibited during pregnancy?
GnRH is inhibited by increased progesterone
this means that there is low LH and FSH
therefore there is no ovarian cycle
what are the different types of maternal adaptations that occur in pregnancy?
what cardiovascular changes occur during pregnancy?
- increased cardiac output
- decreased systemic BP
- decreased total peripheral resistance (TPR)
- increased uterine blood flow
- increased blood volume
- increased plasma and blood cell mass
what respiratory changes occur during pregnancy?
increased alveolar ventilation
displacement of the diaphragm
increased risk of apnea and dyspnea
what GI changes occur during pregnancy?
- increased acid reflux
- delayed gastric emptying - gastroparesis
- these are both due to the foetus pressing on the stomach
what skin changes occur during pregnancy?
- linea nigra - dark line down the central abdomen
- striae gravidae - stretch marks on lower abdomen
- darkened areolar on breasts
what biochemical changes occur during pregnancy?
- weight gain
- increase protein and lipid synthesis
- insulin resistance
how long does pregnancy last for?
40 weeks from day of last menstrual cycle
38 weeks from ovulation/conception
how are contractions prevented in early pregnancy?
most smooth muscles of the myometrium are disconnected from each other
this is maintained by progesterone
what changes occur in the uterus to prepare for contractions in labour?
an increase in oestrogen towards the end if pregnancy signals smooth muscle cells to produce connexins to form gap junctions
this allows coordinated contractions
what is cervical ripening?
it is the growth and remodelling of the cervix
this is due to the breakdown of collagen fibres that seal the uterus
what stimulates cervical ripening?
an increase in oestrogen towards the end of pregnancy
also caused by progesterone and relaxin