pregnancy Flashcards
how much does Q increase by
30-50%
how much does HR increase by
25%
5-10 beats first
total of 15 by 3rd trimester
why does HR increase
increased oestrogen and human chronic gondotropin stimulates HR increase
sympathetic NS actiavation secondary to maintining BP
- oestrogen and progestrogen reduce peripheral vascular resistance by 20% thus HR must increase to maintain BP
how much does SV increase by
25%
why does SV increase
increased blood volume
increased left ventricle
why does blood volume increase
progestrone increases production of renin by kidneys
- Na2+ reabsorption -> kidneys reabsorbs fluid to expand plasma volume
- increased EDV
why does LV size increase
due to maternal hormones
- oestrogen stimulated myocardial hypertrophy and increased contractility
- increased blood volume stimulates some myocardial hypertrophy
- growth is eccentric rather than concentric
how much does blood volume increase by
35-50%
how is the increased blood volume offset
increase in venous capcitance
increased vasodilation at the skin - increase heat loss to help prevent hyperthermia during exercise
why can anemia occur
mismatch of increase in blood volume compared to increase in RBC
results from a relative greater increase in plasma volume than red cell mass
why is there a tendancy to develop varicose veins
relaxationation of the blood vessel walls with hormonal changes and from the pressure of the uterus on the inferior vena cava
effect of exercise on varicose viens
assists blood flow which helps prevent clots and skeletal muscle venous return to help minimize or prevent
how much can reserve volume be reduced by
25%
what pulmonary adapations occur
elevation of diaphragm - pushed up by enlarged uterus
rib cage flares outwrads - reducing fillinf effectivness
effect of exercise on endurance
may improve 12-15 weeks before increase in body weight and uterus size
results from increased blood volume and RBC mass
how much does resting oxygen consumption increase by
15-30%
why does resting oxygen consumption increase
due to enlarging uterus and growing fetus
increased work of breathing
why does CHO usage increase
foetal demand for glucose is large
why does maternal insulin production increase
increase oestrogen casues b-cell hyperplasia
increase insulin production -> hyperinsulinemia
stuimulates lipogenesis by the mother increasing fat deposition
how many women get gestational diabetes
2-3%
why does gestaniional diabetes occur
high levels of intramuscular fat, reduces GLUT 4 activity reducing cho uptake
% of mums who become diabetic 4 years after delievry
60%
effect of gestational diabetes
increased birth weigth
- inceased CHO availiabilty to foetus
- disporportate growth of head and shoulders
baby increases insulin production to counter mother high blood glucose
- insulin is a growth promoter
what is pre-eclampsia associated with
hypertriglyceridemia insulin resistance SNS overactivity atherosclerosis lesoins in placenta increased leptin increased risk of becoming hypertenive
how does exercise help pre-ecpampsia
Reduced levels of C-reactive protein
- C reactive protein stops endothelium producing NO, thus less vasodilation
Increased nitric oxide production by endothelium = vasodilation
Decreased Leptin
effect of decreased leptin
Leptin may contribute to hypertension because of its role in stimulating the body to burn fat. Leptin stimulates SNS activity to burn fat – but this increases blood pressure and lead to hypertension
gastrointestinal changes
Increased plasma progesterone (a smooth muscle relaxant) + increased uterine size
constipation
slowing of gastrointestinal motility
relaxation of the lower oesophageal sphincter, which leads to increased gastric reflux ie: heartburn
muscoskeletal changes during pregenacy
Anterior displacement of the enlarging uterus changes the woman’s
- centre of gravity
- exaggerates normal lumbar lordosis
↑ in hormone levels (especially progesterone, but also relaxin)
- promotes ligament and joint laxity
- Pelvic area susceptible
The enlarging breasts
- centre of gravity moves inferiorly and anteriorly
- increased weight can contribute to upper back and shoulder pain
body mass changes
Average weight gain ≅ 12 kg • fetus 3.5kg • Uterus 1.0 kg • Placenta 0.6kg • Amniotic fluid 0.8kg • Breast enlargement 1.5kg • Maternal fluid gain 2.0kg • Maternal fat 2.5kg
effect on foetus during acute exercise
changes to placenta blood flow
foetal tachycardia
foetal bradycardia
foetal hyperthemia
why does placenta blood flow change during actue exercise
changes in uteroplacental blood flow
the flow of blood through the placenta remains unchanged, but the flow of blood to the pregnant uterus is reduced, as it is for any organ during exercise.
Foetal oxygen supply not compromised or slightly reduced
- Compensatory increased placental a-vo2 difference (Baby extracts more)
Return to normal (or even higher temporarily) after 20 minutes of stopping
why can foetal tachycardia occur during exercise
>160bpm Foetal HR + 10-30 beats during exercise Reduced blood flow? Response to circulating maternal catecholamines during exercise Increased maternal core temperature
why can foetal braycardia occur during exercise
<120bmp
Response to hypoxia, to reduce foetal O2 demands
Is seen mostly in long-duration exercise and / or post-exercise
why can hyperthermia occur during acute exercise
Foetal temp is about 5 °(F) higher than maternal temp – thus baby loses heat via this gradient
Could increased maternal temp during exercise reduce heat gradient, plus reduced uterine blood flow meaning less blood is available to remove heat, cause foetal hyperthermia and damage?
No evidence for this as increased sweating, enhanced peripheral vasodilation helps to cool mother’s core temp.
effect of chronic exercise on birth weight
Findings have been inconsistent
Feotoplacental growth higher in active mothers
Feotoplacental growth lower in active mothers
Birth weight appears unaffected in women who maintain adequate energy balance (diet = exercise)
Mothers who continue to perform a high volume of exercise in mid to late pregnancy, have thinner + lighter babies (200-400g less)
effect of chronic exercise on gestational length
The concern is that increased norepinephrine and prostaglandin output during exercise could stimulate uterine activity and premature labour.
No real supportive evidence to confirm this
contridiction to exercise
prior to starting
absolute
Haemodynamically significant heart disease
Restrictive lung disease
Incompetent cervix
Known risk of premature labour
Persistent 2nd or 3rd Trimester bleeding
Placenta previa after 26 weeks
Premature labour during current pregnancy
Ruptured membranes
Preeclampsia
Severe anaemia
contridiction to exercise
relative
Severe anaemia Unevaluated maternal cardiac dysrhythmias Chronic bronchitis Poorly control type 1 diabetes Extreme morbid obesity Extreme underweight (BMI <12) History of extremely sedentary lifestyle Intrauterine growth restriction Poorly controlled hypertension Orthopaedic limitations Poorly controlled seizures Poorly controlled hyperthyroidism Heavy smoker
reasons to stop exercise
Excessive shortness of breath Chest pain or palpitations Presyncope or dizziness Painful uterine contractions or preterm labour Leakage of amniotic fluid Vaginal bleeding Excessive fatigue Abdominal pain, particularly in back or pubic area Pelvic girdle pain Reduced foetal movement Dyspnoea before exertion Headache Muscle weakness Calf pain or swelling
things to be aware of during first trimester and exercise
preventing hyperthermia - adequate hydration - wear appropriate clothing - environment not to hot or cold temp should not excedd 37.8
what exercise can be done
low risk pregnancy - moderate exercise 30-30 mins on most days
aim towards 150 MVPA
participation in team sports for first 15 weeks
submax exercise reponse
weigth supported - O2 cost is the same
weight bearing - increase in VO2, cost proportional to weigth
higher HR, SV, VE and Q compared to non preg
why is cho delivery to mucsle reduced during submax
reduced liver glycogen stores
reduced sympathoadrenal activation reduces catecholamin production reducing delivery of CHO to muscles
foetal dmenad for CHO takes priority
what aerobic exercise can be done
3+ days a week low impact - cycling, walking 20-30 minute sessions Hr 120-160, 40-60-90% HRmax RPE 13-14
what resistance training can be done
for women already doing, can continue
light to mod loads, 12-15 reps
avoid exercise using valsalvas manoeuvre in 3rd trimester
abdominal conditionimg in 1st and 2nd
what flexibilty can be done
stretches - not to max ROM
nothing that requires great balance due to chnage in CoG
low impact
get up slowly - BP
how many extra calories are required in each trimester
1st - 100
2nd - 300
3rd -450
does it help being fit during labour
mininmal research evidence
hypothetically - higher VO2 should allow female to cope better with O2 demand of labour
when can you start exercise post partum if no compliactions
walking, plevic floor exercises and stretching may begin immediately
when can you start exercise psot partum if compliactions
caesarean - medical caregiver consulted first, usually at 6-8 week check up
why exercsie post partum
may help reverse weight gained during pregnancy
most weight loss occurs in 1st 3 months
no increased weight loss be exercising and breastfeeding due to increase EI
effect of training after giving birth
peak VO2 increased by 10-25%
BMD naturally declines in lactating women
improved insulin sensivivity
improves body image, psychological well being
