Maternal Changes in Pregnancy Flashcards Preview

Reproduction (Physiology 2) > Maternal Changes in Pregnancy > Flashcards

Flashcards in Maternal Changes in Pregnancy Deck (51)
Loading flashcards...
1
Q

What are the causative factors of maternal changes during pregnancy?

A

High levels of steroids (oestrogen & progesterone)
Mechanical displacement
Fetal requirements

2
Q

What are the repercussions on different systems after pregnancy?

A

Pregnancy is a physiological event. Systems (usually) return to normal after delivery, but not all

3
Q

How would we identify an abnormal pregnancy?

A

To diagnose abnormality in pregnancy need to detect changes in the changes

4
Q

Why may pregnancy make it difficult to identify disorders?

A

Pregnancy may:

  • exacerbate a pre-existing condition
  • uncover ‘hidden’ or mild condition
5
Q

What main events do pregnancy changes occur to cope with?

A

Changes designed to cope with several main events:

  • increase in size of the uterus
  • increased metabolic requirements of uterus
  • structural and metabolic requirements of fetus
  • removal of fetal waste products
  • provision of amniotic fluid
  • preparation for delivery and puerperium
6
Q

What systems undergo maternal changes during pregnancy?

A
energy balance
respiratory system
cardiovascular system
gastrointestinal system
urinary system 
endocrine system
7
Q

What placental peptides cause maternal changes?

A

placental peptides

hCG, hPL, GH

8
Q

What is the role of maternal steroids?

A

placenta takes over ovarian (CL) production around wk 7

9
Q

Name the maternal and foetal steroids

A

progesterone, oestradiol, oestriol

10
Q

What are the maternal and fetal pituitary hormones?

A

GH, thyroid hormones, prolactin, CRF

11
Q

What systems do the placental steroids affect?

A
  • renin/angiotensin system
  • respiratory centre
  • GI tract
  • blood vessels
  • uterine myometrial contractility
12
Q

How does weight change across pregnancy?

A
> total gain in weight    12.5-13kg
Fetus plus placenta	5 kg
Fat and protein		4.5 kg
Body Water 
(this is excluding that in other listed structures)	1.5 kg 	intravascular, interstitial, intracellular 
Breasts			        1 kg
Uterus				0.5- 1kg
Ideally keep to less than 13kg: failure to gain or sudden change needs monitoring
13
Q

How is an energy balance maintained during pregnancy?

A

Energy output and storage is increased

14
Q

Why is energy output increased?

A

to cope with increased respiration and cardiac output

15
Q

Why is energy storage increased?

A

for fetus

for labour and puerperium

16
Q

Why does fat and protein stores increase by 4-5 kg?

A

increased consumption and reduced use
mainly laid down in anterior abdominal wall
utilised later in pregnancy and puerperium

17
Q

How much does the metabolic rate rise by during gestation?

A

350 kcal/day mid gestation 75% fetus and uterus

250 kcal/day late gestation 25% respiration(H&L)

18
Q

What is the significance of glucose during pregnancy?

A
  • need increased availability in 2nd trimester
  • active transport across placenta as fetal energy source
  • fetus stores some in liver
19
Q

Descrube the maternal reserves of glucose in the 1st trimester

A
1st Trimester
Maternal reserves
pancreatic β cells increase in number
plasma insulin increases
fasting serum glucose decreases
(laid down as stores and  used by muscle)
20
Q

Describe he fetal glucose reserves in the 2nd trimester

A
2nd Trimester
Fetal reserves
hPL causes insulin resistance 
ie less glucose into stores = increased availability  in serum 
glucose (more crosses placenta) 
but can cause diabetes
21
Q

How is the RAAS system affected during pregnancy?

A

Total water gain
E₂ and particularly P act on renin angiotensin system
Retain fluid better and thirst increases. Plasma levels increase - common for oedema to occur
Albumin levels drop decreasing oncotic pressure

22
Q

How is respiration affected during gestation?

A

Oxygen consumption is increased
Bigger deeper breaths taken more frequently causing a 40% increase in minute volume → larger Oxygen pressures in arteries removal of more CO2

Facilitates gas transfer for baby

23
Q

What is haemodilation?

A

The apparent anaemia as concentration of Hb falls

24
Q

How does maternal blood adapt for gestation?

A

increased efficiency of iron absorption from gut
Also changes in white cells (up) and clotting factors..blood becomes hypercoagulable = increased fibrinogen for placental separation, but increased risk of thrombosis

25
Q

Describe fetal blood

A

Fetal blood = increased Hb and altered in type → Increased O binding → oxygen given up by maternal Hb

26
Q

What is the effect of smoking on fetal blood?

A

smoking increases maternal carboxy-Hb which is more permanent and reduces the increased binding = fetal hypoxia

27
Q

What effect does the expanding uterus have on the heart?

A

pushes heart round

changes ECG and heart sounds

28
Q

Why does pregnancy cause an increased CO?

A

increased heart rate and stroke volume
begins as early as 3 weeks to max 40% at 28 weeks
for maternal muscle and fetal supply

29
Q

How is vasculature affected by pregnancy?

A

Increased cardiac output and vasodilation by steroids = Reduced peripheral resistance

30
Q

Where is there increased blood flow to during pregnancy?

A
uterus
placenta
muscle
kidney 
skin
31
Q

How does the body adjust for heat loss during pregnancy?

A

Neoangiogenesis including extra capillaries in skin (spider naevi) to assist in heat loss

32
Q

Describe the effects of progesterone on the GI tract

A

Progesterone causes relaxation of muscles especially uterus. Relaxes smooth muscle on gut - can cause constipation as transit time prolonged in gut.

33
Q

Why is heartburn a common problem in pregnant women?

A

Also relaxes the lower oesophageal sphincter - in late pregnancy 3rd trimester, heartburn is a very common problem

Worsens as pregnancy goes on as uterus enlarges and pushes up on intestines

34
Q

What is the significance of folic acid?

A

Folic acid vital for foetal wellbeing and DNA production

35
Q

What disorder is folic acid deficiency associated with?

A

Deficiency linked to spina bifida- neural tube defect

36
Q

How much folic acid is recommended to take?

A

Supplementation advised 5mg/ day up to week 12

37
Q

How is the urinary tract affected by pregnancy?

A

Smooth muscle relaxation of urinary tract as well. Bladder, ureters and collecting systems in kidneys relax - dilated

38
Q

What is a consequence of muscle relaxation of the urinary system?

A

Can cause urinary stasis causing UTIs

39
Q

During pregnancy, how does increased CO affect the urinary system

A

If you have a 40-50% increase in CO => 40-50% increase in GFR → causes removal of urea and creatinine (v. low in pregnancy)

40
Q

What causes an increase in urine frequency in the first trimester of pregnancy?

A

Urinary frequency is very common in first trimester of pregnancy
Uterus enlarges and pushes onto the back of the bladder

41
Q

Describe the pressure on the bladder in the later trimesters of pregnancy

A

2nd trimester pressure eased off bladder

3rd trimester foetus head descends pushing onto bladder increasing urinary frequency

42
Q

Why is the bladder so sensitive to uterine enlargement?

A

The bladder cannot distinguish between inside (trigone) or outside pressure - causes increased weeing

43
Q

Explain the chnage in uterine size

A

Huge increase in muscle mass
Huge increase in blood flow
placenta and uterus = 1/6 of total
14000 mls (but not solid!)

44
Q

Why does the uterus expand during gestation?

A

As the baby grows, amniotic sac expands and uterus gets bigger.

45
Q

Describe the structure of the uterus during the third trimester

A

3rd trimester (24 wks +) expansion from the cervix and lower part of the cervix is less muscular and more fibrous

46
Q

Why is a lower cesarean section normally carried out

A

During cesarean a lower segment cesarean takes place as its more fibrous and less muscular - less bleeding

47
Q

Why is the upper part of the uterus so muscular?

A

Towards top of uterus is very thick and muscular for pushing baby out

48
Q

What is the primary function of the cervix during pregnancy?

A

primary function is to retain the pregnancy

49
Q

How does the cervix change during pregnancy?

A
Increase in vascularity
Tissue softens from 8 weeks
- changes in connective tissue
- begins gradual preparation for expansion
Proliferation of glands
50
Q

What are the effects of gland proliferation?

A

mucosal layer becomes half of mass
great increase in mucus production
Progesterone causes thickening of cervical mucus plug protective..ie anti-infective

51
Q

How does the body return to normal?

A
  • Dramatic and rapid fall in steroids on delivery of the
    placenta
  • Most endocrine-driven changes return to normal rapidly
  • Uterine muscle rapidly loses oedema but contracts
    slowly: never returns to pre-pregnancy size
  • Removal of steroids permits action of raised prolactin on
    breast