Maternal Physiology, Labour & Lactation

Question 1

What causes morning sickness?

Answer 1

increase in HCG

Question 2

What changes occur in a women body during pregnancy (e.g. CO or GFR)?

Answer 2

increase in:

• CO and BV (greater metabolic demand)
• O2 consumption & CO2 production
• ventilation
• BMR
• GFR increase in sodium and water reabsorption
• Nutritional demand
• weight about 10 kg

Question 3

What nutrients are needed more in pregnancy?

Answer 3

• normal healthy diet capable to supporting foetus

- With extra macronutrients and vitamins and iron and calcium without extra can get anaemia or demineralisation of bones

Question 4

What hormone is secreted to prepare for birth?

Answer 4

Relaxin and oesterogen

Question 5

What does relaxin stimulate?

Answer 5

• Cervix softening and dilation

- pubic symphysis becomes more flexible

Question 6

What does oestrogen stimulate?

UNFINISHED

Answer 6

• Uterine muscle becomes more excitable and more connected electrically and mechanically by gap junctions
• increase in prostaglandin and oxytocin receptors
• Increase in foetal CRH (corticotrophin releasing hormone) production
• inc CRH means more ACTH and cortisol
• cortisol vital in final maturity of foetal respiratory system

Question 7

What are the three stages of labour?

Answer 7

1) Dilation of cervix (8-24 h)
2) expulsion of foetus (30-90 min)
3) Placental delivery (15-30 min)

Question 8

What occurs in stage 1 of labour?

Answer 8

• myometrial contraction
  push babies head down stretching the cervix
• stretch on cervix triggers release of oxytocin from posterior pituitary
• oxytocin further increases contractions (positive feedback cycle)
• prostaglandins also stimulate contractions

Question 9

What occurs in stage 2 of labour?

Answer 9

• head of baby exiting cervix activates abdominal contractions (stronger than myometrial)
• these are reflex contractions but can be reinforced by voluntarily pushing
• Bearing down will help

Question 10

What occurs in stage 3 of labour?

Answer 10

• Placenta comes off uterine wall

- Low blood loss as uterus already contracted

Question 11

What hormones initiate the breast development in pregnancy?

Answer 11

• oestrogen (completes duct development)
• progesterone (enlarges terminal secretory alveoli)
• Human chorionic somatomommotropin and prolactin (stimulate enzyme release)

Question 12

When can women start producing milk?

Answer 12

20 weeks after fertilisation however high levels of female steroids (oestrogen and progesterone) prevent this until birth occurs where levels of steroids will drop

Question 13

What stimulates milk production?

Answer 13

• drop in female steroid hormones allow lactation and suckling to proceed
• both processes are neuroendocrine so need nervous afferents and endocrine effectors
• mechanical stimulation triggers milk production

Question 14

What are the components of great milk?

Answer 14

• Triglycerides, carbs, protein, vitamins, calcium and phosphate
• colostrum secretion has more protein and less fat and lactose also contains lactoferrin (antibac) and maternal IgA to give passive immunity

Question 15

What is colostrum?

Answer 15

First few days milk secretion called colostrum

Question 16

What are the components of breast milk?

Answer 16

• Triglycerides, carbs, protein, vitamins, calcium and phosphate
• colostrum secretion has more protein and less fat and lactose also contains lactoferrin (antibac) and maternal IgA to give passive immunity

Question 17

Why does GFR and sodium and water reabsorption increase in pregnancy?

Answer 17

• maternal sex steroids act like mineralocorticoids to increase renal reabsorption
• GFR raised to limit resulting fluid retention

Question 18

What can dyspnoea in pregnancy cause?

Answer 18

Late pregnancy and acid reflux due to mechanical effects of where the foetus is situated

Question 19

What is lochia?

Answer 19

discharge post birth caused by regression of the decidual endometrium

Question 20

What occurs to hormone levels post birth?

Answer 20

Progesterone and oestrogen levels drop due to loss of placenta which was producing them

Question 21

What is suckling reflex?

Answer 21

liberation of prolactin from hypophysis evoked by stimulation of nerves in the nipple during act of suckling

Question 22

How does mechanical stimulation cause milk production?

Answer 22

• decrease in secretion of prolactin inhibiting hormone resulting in increase in prolactin (PRH) also helps
• these initiate and maintain milk production

Question 23

How does mechanical stimulation cause milk release from the nipple?

Answer 23

• Increase oxytocin release from hypothalamus

- oxytocin causes smooth muscle contraction in secretory alveoli and expulsion of milk