Maternal adaptation to pregnancy Flashcards
early in pregnancy, changes may be considered ______
whereas later they may be considered as ______
anabolic = early
catabolic = later - mobilsiation of fuel reserves, as demands of fetus are high
how do oestrogen and progesterone show synergy?
oestrogens increase the expression and sensitivity of the progesterone receptor.
Progesterone, hCG and hPL are produced by the _______
Progesterone, hCG and hPL are produced by the placenta
the oestrogens are synthesised by a ….
the oestrogens are synthesised by a feto-placental unit
where does proactin come from?
maternal pituitary
does progesterone increase throughout the pregnancyu?
increases consistently to term
describe the effects of the early sex hormone changes in pregnancy
These merge with the luteal phase of the ovarian cycle.
Progesterone suppresses menstruation, uterine contractions and hypothalamic cycling.
Oestrogens increase uterine blood flow and vessel growth.
Together, these two steroids cause growth of the uterus and mammary tissue (see Lactation lecture).
describe the effects sex steriod changes have - mid gestation.
how does the soruce of progesterone change?
Rising progesterone and oestrogen levels continue to stimulate uterine and mammary growth without stimulating function.
Source of progesterone changes from ovary to placenta at 12-16 weeks. This is a vulnerable period for maintaining a pregnancy.
describe the late gestational changes due to changes in levels of sex sterioda
In most mammalian species, there is a fall in progesterone and an increase in oestrogen concentrations before parturition but this does not appear to occur in women, although changes in the oestrogen to progesterone ratio may occur at the tissue level.
diagram for effects of progesterone, progesterone + oestrogen, and oestrogen
the production of prolactin leads to enlargement of what?
the maternal pituitary anterior gland
does prolactin levels increasing elad to changes in the strucutre of the mammary glands?
yes
problems with pituitary enlargement due to increased prolactin secretion?
Pituitary enlargement may cause visual problems through pressure on the optic chiasma, and renders the gland vulnerable to ischaemic necrosis in the event of post-partum haemorrhage or similar vascular incident
whats Sheehans syndrome?
Sheehan’s syndrome is a condition that affects women who lose a life-threatening amount of blood in childbirth or who have severe low blood pressure during or after childbirth, which can deprive the body of oxygen.
This lack of oxygen that causes damage to the pituitary gland is known as Sheehan’s syndrome
role of human placental lactogen?
Produced by the syncytiotrophoblast of the placenta.
hPL stimulates maternal appetite, lipolysis and maternal utilization of fat in preference to glucose, and growth of the mammary tissue.
how is relaxin important in pregnanyc?
origin: corpus luteum, placenta, decidua
actions: vasodilator, softens ligaments and cervix in late pregnancy
describe leptins importance in pregnancy
Leptin is secreted by the placenta, but pregnancy is a state of peripheral leptin resistance, allowing for deposition of fat stores
how are fetal caclium demands met?
Fetal demands are met mostly by increased Ca++ uptake from the maternal gut, with some release from the maternal skeleton towards term when mineralization of the fetal skeleton is at a peak.
Calcium excretion in maternal urine actually increases, and double by term.
describe how adrenal cortical hormones are involved in pregnancy
Adrenal cortical hormones.
Increased concentration of cortisol and aldosterone due to an oestrogen stimulated increase in binding globulins, and CRH from the placenta.
describe the role of pregnancy-associated plasma protein A in pregnancy?
origin: placenta
actions: protease that cleaves IGF binding protein and so regulates availability of IGF. Low values associated with fetal growth restriction
Maternal pituitary gland increases in size by ____% in pregnancy
Maternal pituitary gland increases in size by 30-50% in pregnancy
describe how the adrenal gland cahnges in function during pregnancy
- Increased activity of the renin-angiotensin system leads to a rise in aldosterone
- There is a ~3 fold rise in cortisol levels after the first trimester, both free and bound
- Rise in cortisol driven primarily by corticotropin releasing hormone (CRH) secreted by the placenta
- Cortisol may contribute to the hyperglycaemia seen in pregnancy
give 5 broad physiological categories for change during pregnancy
Cardiovascular
Respiratory
Renal
Metabolic
Physical
how does cardiac function change during pregnancy
- Increased CO (both SV and HR increase)
- occurs early in first trimester - most likely in respone to maternal vasodialtion
- mainly to tissues with increased demand e.g. reproductive tissue (uteroplacental circulation), gut (increased food uptake), kidney (excretion of waste) and skin (dissipation of heat generated by fetus).
*
T or F
Pregnant uterus may impede venous return in certain postural positions.
T
describe how blood volume changes during pregnancy
- 1st 2 trimersters: 40% increase in maternal blood - to fill dilated maternal circulation
- due to upregulation of the renin-angiotensin system and increased sodium and water retention by the kidney.
desribe how the blood composition changes during pregnancy
- blood volume increases = haemodilution
- then RBCs rise in count due to erythropoietin
- no change in RBC half life
- alsdo dilution of platelets
- risk of thromboelbolic disease - as fibrinolysis is decreased due to PAI-2 being released form the placenta
how does blood pressure change during pregnancy?
decrease in early-mid pregnancy and then an increase towards term
- Decrease due to the vasodilation of maternal circulation due to relaxin and progesterone mediated smooth muscle relaxation, and increased nitric oxide synthase activity, coupled with reduced peripheral responsiveness to angiotensin II
*
what is pre-eclampsia
Pre-eclampsia is defined as de novo hypertension of 140/90 mmHg starting after 20 weeks of gestation. Some older definitions include proteinuria (>300 mg in 24 hours) and peripheral oedema.
The syndrome is characterized by generalized endothelial cell activation in response to factors released by a poorly perfused placenta.
might there be heart murmurs during pregnancy
The increased cardiac output can lead to systolic murmurs as the blood flows over the aortic and pulmonary valves.