Lecture 1: Pregnancy and Labour

Question 1

What care is Obstetrics involved in

Answer 1

Care during pregnancy concerning conception, fetal growth and development and management of maternal conditions exacerbated by pregnancy

Care during birth: timing and managing birth stress for neonate

Question 2

k

Answer 2

j

Question 3

What are the time frames for the 3 stages of labour

Answer 3

1: From onset of regular contractions to the cervix being fully dilated
2: From fully dilated to delivery of the baby
3. From delivery of baby to delivery of the placenta

Question 4

Describe the intrauterine factors that influence growth and development of the fetus

Answer 4

Adequate nutrition via the placental circulation,

Question 5

Describe the structure of the placental circulation

Answer 5

Placental circulation is where oxygen and nutrients diffuse over and actively transported across from maternal blood that bathes mesh of fetal blood vessels intertwined with umbilical cord

Question 6

In what cases is the fetus not recieving adequate nutrition to enable them to achieve their genetic potential

Answer 6

• Increased nutrition (diabetic mother= excess glucose)

- Reduced nutrition (utero-placental failure)

Question 7

What factors affect how we determine genetic growth potential

Answer 7

Maternal age, parity, BMI, ethnicity and fetal sex.

Chromosomal abnormalities reduce fetal growth potential

Question 8

In what cases is the fetus not receiving adequate nutrition to enable them to achieve their genetic potential

Answer 8

• Increased nutrition (diabetic mother= excess glucose)

- Reduced nutrition (utero-placental failure)

Question 9

What factors affect how we determine genetic growth potential

Answer 9

Maternal age, parity=number of babies over 20 weeks, BMI, ethnicity and fetal sex.
Chromosomal abnormalities reduce fetal growth potential

Question 10

What does Utero-placental failure cause?

Answer 10

Reduced placental perfusion means reduced nutrients and oxygen to fetus
so Fetus conserves energy by restricting growth (abdominal) but brain sparing

Question 11

What are growth restricted fetuses at risk of

Answer 11

Preterm, still birth and neonatal death

Question 12

What are growth restricted fetuses at risk of

Answer 12

Preterm, still birth and neonatal death

Question 13

What are the main environmental causes of growth restriction in fetuses

Answer 13

• Drugs (smoking, alcohol and medications)

- Infections (toxoplasmosis, rubella etc)

Question 14

Define IUGR, Small for gestational age (SGA) and large for gestational age (LGA)

Answer 14

IUGR: interuterine growth restriction - fetus unable to achieve their growth potential
SGA= (<10th percentile)
LGA= (>90th percentile)

Question 15

Are birth weights related to gestation time? What is low, v low and extremely low birthweight compared to macrosomic birthweight. Why is this measure used

Answer 15

Birth weight is not related to gestation period and is used because these babies have bigger risk for neonatal complications. 
Lbw: <2500 g
vlbw:<1500 g
Elbw:<1000 g 
Macrosomic: >4kg

Question 16

What are the challenges with determining if a baby has IUGR and what tool can be used to help this

Answer 16

Depending on the genetically determined growth potential a SGA baby may not have IUGR and a normal baby may have IUGR if it was determined to be a LGA baby. Using a customisable growth chart based on maternal characteristics, the placement of the percentiles can be more accurate for what is expected

Question 17

What happens in the first stage of labour

Answer 17

The fundus of uterine muscle contracts, pushing the fetus down onto the cervix causing cervical change to dilate to 10 cm

Question 18

What is the dangerous part of first stage of labour that requires monitoring of the fetal heartbeat. Which babies are more susceptible ?

Answer 18

During contraction placental blood flow reduces, for up to 90 secs- leading to relative hypoxia.
Growth restricted/ pre term babies are more susceptible to fetal distress & hypoxia.

Question 19

What happens in the second stage of labour and what needs to watched out for

Answer 19

Baby can have passive descent with epidural but for majority its active pushing out.
Fetus needs to more closely monitored as oxygen requirements increase in the 2nd stage

Question 20

What are alternatives to normal vaginal birth and in what circumstances are these

Answer 20

Assisted vaginal birth using forceps or ventouse (suction cap) that pulls guides the head out.
Only performed if concerns with fetal wellbeing or maternal exhaustion as can be associated with maternal and fetal trauma

Question 21

What happens in the 3rd stage of labour and what is the risk associated at this stage

Answer 21

Uterus muscles contract to mechanically obstruct maternal placental vessels and the placenta separates. Risk is post partum haemorrhage where uterus doesn’t contract well and >500 ml of blood loss 24hrs after delivery. Can lead to postpartum anaemia - reduced breast milk production, poor bonding and post natal depression

Question 22

What are the risks of caesarean section

Answer 22

Elective CS prediposes the newborn to respiratory complications (wet lungs) because the lung fluid isn’t being squeezed out by contractions and can lead to 6 week maternal recovery

Question 23

What are the main changes in ‘Transition’ (fetus going to baby) for gas exchange, ventilation, etc

Answer 23

Gas exchange goes from placenta to pulmonary with ventilation gaseous instead of liquid.
Instead of relying on the sterile uterine environment it must regulate its own body temp, glucose homeostasis and nutrition.

Question 24

Compare the changes in respiratory system that occur before and at birth

Answer 24

Before birth the lungs stop secreting lung fluid in late pregnancy and labour squeezes lung fluid out, increasing its absorption via lymphatics.

At birth the baby’s first cry changes pulmonary dynamics, breathing is stimulated through tactile and thermal stimulation and the umbilical cord is delayed clamped

Question 25

What happens when the umbilical cord is clamped

Answer 25

The low resistance placental circulation is removed and there is an increase in systemic blood pressure

Question 26

Why is the first breath/cry so important

Answer 26

• helps to establish Residual volume and therefore functional residual volume vital for maintaining lung expansion

Question 27

Describe the path of oxygenated blood getting to the brain in the fetus

Answer 27

1. oxygenated blood (80% sat) enters fetus from placenta via the umbilical vein
2. This joins the fetal circulation via the Ductus Venosus into the inferior vena cava.
3. mixed with partially deoxy blood, it enters the RAtrium where it is diverted by Crista dividens through the Foramen Ovale to the LAtrium
4. And this sends the most oxygenated blood to the brain

Question 28

Describe the path of deoxy blood returning from the upper body

Answer 28

1. Deoxy blood from upper body returns to RAtrium via superior vena cava where it goes to the main pulmonary artery
2. 87% of blood ejected from RV is diverted through the Ductus arteriosus to descending Aorta
3. Blood returns to the placenta via two umbilical arteries which attach to the common illiac arteries

Question 29

Which ventricle pumps the lower 2/3 of the body and upper 1/3 of body.

Answer 29

Right pumps lower. Left pumps higher

Question 30

What is the difference before and after birth the output of RV to the lungs

Answer 30

Before birth only 13% because of high blood pressure in the lungs but after birth 100%

Question 31

What is the difference at birth and after birth the blood pressure between of right and left side of heart

Answer 31

At birth blood pressure is similar in each ventricle so shouldn’t hear murmurs
After birth left ventricle higher pressure than right

Question 32

What things close in fetal circulation after birth

Answer 32

Ductus arteriosus functionally and then structurally closes. Foremen ovale and ductus venosus closes too

Question 33

What are the possible conditions for failure of transition for respiratory, cardiovascular, metabolic, thermoregulatory, GI and Renal.urinary systems- seem in pre term babies

Answer 33

pulmonary hypertension, patent ductus arteriosus: too much blood in the lungs , hypoglycaemia, hypothermia, failure to thrive and hyperkalaemia

Question 34

More babies you have…

Answer 34

the bigger they get