Maternal Physiology , Labour and Lactation

Question 1

Why do women get Morning Sickness in pregnancy

Answer 1

Feature of early pregnancy because of the human chorionic gonadotrophin secreted by the trophoblast.
Diminishes after first trimester

Question 2

Explain what happens to CO in pregnancy

Answer 2

Cardiac output increases to 130-140% by 20 weeks gestation.

Question 3

What happens to BV in pregnancy

Answer 3

Blood volume rises by 20% mostly at the second half of the pregnancy. rises almost 40% by the the end of pregnancy

Question 4

What happens to O2 consumption and CO2 production in pregnancy

Answer 4

O2 consumption and CO2 production increase. Therefore VO2 and VCO2 increases to keep up with demand of fetal metabolism.

Question 5

What happens to BMR in pregnancy

Answer 5

15% increase in BMR

Question 6

What happens to GFR and NA/H20 reabsorption in pregnancy

Answer 6

• Renal reabsorption of NaCl and H2o is elevated by high levels of maternal sex steroids having aa mineralocorticoid like effect.
• GFR is raised indirectly by increased CO and directly to limit fluid retention

Question 7

When can frequency of urination increase during pregnancy

Answer 7

During the third trimester when the fetus might be pressing on the bladder

Question 8

What are pregnant women prone to be deficient of

Answer 8

Iron and Calcium

Question 9

Explain the increased nutritional demands in pregnancy

Answer 9

Energy and protein intake of an average diet is adequate but mineral and vitamin intake is not. Additional 1 g of iron is needed and calcium

Question 10

What happens if there is a calcium deficiency in pregnancy

Answer 10

Deminiralising of maternal bones

Question 11

What is the usual weight gain during pregnancy and why

Answer 11

Weight gain : 10 kg 
1- fetus : 3.5 kg 
2- breast development : 1 
3- placenta and amniotic fluid : 2.5 
increased body weight in mother : 3.5 kg

Question 12

What mechanical effects could be caused due to where the fetus is in the abdomen

Answer 12

1- Dyspnoea late in pregnancy

2- acid reflex

Question 13

What is the average duration of pregnancy

Answer 13

270 days ( 284 from last menstruation )

Question 14

Explain Parturition

Answer 14

Birth happens in 3 stages
1- dilation of cervix
2- explosion of fetus
3- delivery of placenta

Question 15

Explain the preparation stage of parturition

Answer 15

During last trimester
1- cervix softens and dilates
2- pubic symphysis becomes more flexible
3- smooth muscle of uterus becomes more excitable and connected via gap junctions ( under estrogen levels )
4- prostaglandin production increases and oxytocin receptors rise
5- CRH production increases that has a positive feedback on placenta , increasing fetal ACTH and cortisol.

Question 16

Why is increase of cortisol vital in the last trimester

Answer 16

Cortisol is vital to maturity of fetal respiratory system and preparation of change in environment.

Question 17

When is the fetus ready to be born

Answer 17

After CRH production has been increased

Question 18

How many stages of labour are there

Answer 18

3 stages

Question 19

Explain the 1st stage of labour

Answer 19

Lasting 8-24 hours
1- canal trough cervix is dilated by babies head pushing down by myometrial contractions
2- stretch causes reflex release of oxytocin from posterior pituitary that acts on myometrium to increase contraction and thus increase cervical stretch
3- 1st stage lasts until 10cm dilation of cervix

Question 20

Explain the 2nd stage of labour

Answer 20

Lasting 30-90 min
1- Once cervix is 10cm dilated head of baby exiting cervix will trigger reflexes to contact abdominal muscles
2- Reflex contractions could be reinforced voluntarily by pushing ( not necessary though )
3- Contraction expels baby out of vagina

Question 21

Explain the 3rd stage of labour

Answer 21

Delivery of the placenta that shears off wall of contracted uterus. Because the uterus is contracted there is usually minimal blood loss.

Question 22

What is lochia and why does it happen

Answer 22

Regression of decidual endometrium giving discharge post birth called lochia.
Due to the dramatic drop of estrogen and progesterone levels after loss of placenta.

Question 23

When do breasts fully develop in pregnancy

Answer 23

During the third trimester , at 20 weeks women is able to produce milk but prevented by high levels of estrogen and progesterone until birth.

Question 24

How do breasts develop to secrete milk ( explain hormones )

Answer 24

Breasts develop to secrete milk under influence of estrogen and progesterone from placenta.
1- estrogen promotes duct development
2- progesterone enlarges terminal secretory portions of glands
3- prolactin ( from mom ) and human chorionic somatomammotropin ( from placenta ) develop enzymes for milk production

Question 25

How mechanical stimulation of nipple causes breastfeeding

Answer 25

1- suckling stimulates hypothalamus via spinal cord afferents
2- causes secretion of prolactin via anterior pituitary by decreasing Prolactin inhibitor hormone secretion
= initiates and maintains milk production ( endocrine )
3- nipple stimulation will increase oxytocin from hypothalamus that contracts smooth muscle surrounding secretory alveoli = milk expelled into mouth of infant ( neurological )

Question 26

What is the advantage of suckling being a neuroendocrine reflex

Answer 26

It has to be an instantaneous process, and well controlled. Easier to do that if it’s not just neuro controlled

Question 27

How Can breastfeeding act as an unreliable contraceptive

Answer 27

Prolactin inhibits gonadotrophin production, which inhibits FSH and LH

Question 28

Why is breastfeeding not a reliable contraceptive

Answer 28

Because breastfeeding is pulsatile , if women misses a feed then gonadotrophin will not be inhibited.

Question 29

What are the components of breast milk

Answer 29

1- Triglycerides 
2- carbohydrates : lactose 
3- protein 
4- vitamins 
5- calcium 
6- phospate

Question 30

What is secreted after the first few days by the breasts

Answer 30

Colostrum what has more protein and less fat and glucose than normal breast milk. 
Contains lactoferrin ( antibacterial ) and maternal antibodies ( IgA ) for immunity