Pregnancy

Question 1

What maternal changes might occur in the first trimester of pregnancy

Answer 1

Altered brain function, hormones, fluid balance and immune system

Question 2

What maternal changes might occur in the second trimester of pregnancy

Answer 2

Increased blood volume and blood clotting tendency
Decreased blood pressure
Altered fluid balance

Question 3

What maternal changes might occur in the third trimester of pregnancy

Answer 3

Increased weight

Altered joints

Question 4

Describe the endocrine changes during pregnancy

Answer 4

hCG peaks around week 9 then rapidly falls

Progesterone, oestrogens (oestriol) and placenta lactogen increase throughout pregnancy 100-1000 fold compared to levels in non-pregnant women

Question 5

What is the conceptus

Answer 5

Everything resulting from the fertilised egg (baby, placenta, fetal membranes, umbilical cord)

Question 6

Distinguish between embryo, foetus and infant

Answer 6

Embryo – the baby before it is clearly human

Fetus – the baby for the rest of pregnancy

Infant – less precise, normally applied after delivery

Question 7

Describe the overall timing of maternal and placental changes during pregnancy

Answer 7

Maternal changes occur throughout

Placental changes are complex, mostly occurring in the first half

Question 8

At how many weeks can a baby be born and survive without modern Neo-natal ICU and how is this affect by the unit

Answer 8

26 weeks

With unit - pushed back to 22

Question 9

When in pregnancy is risk of miscarriage greatest

Answer 9

before 13 weeks i.e. first trimester

Question 10

Define the features of the first trimester (0-13 weeks) of normal human pregnancy

Answer 10

The most dangerous time for the foetus
95% of pregnancies that survive the first trimester → term
Most “embryology” takes place in this period – complex
Focus on structural development not growth

Question 11

Define the risks of the first trimester (0-13 weeks) of normal human pregnancy

Answer 11

Chromosomal abnormalities → miscarriage
Most susceptible to insult → congenital abnormalities
Placental problems → miscarriage, pre eclampsia

Question 12

What is viability

Answer 12

the foetus can survive if born

Question 13

Define the features and risks of the second trimester (14-26 weeks) of normal human pregnancy

Answer 13

Safest time for the baby and the mother
Fetal weight increases from 50g – 1000g
Uterine stretch
Progesterone levels continue to increase
Estrogens increase

Question 14

What is the main purpose of the second trimester

Answer 14

The foetus becomes viable in this trimester

Question 15

What is viability limit and survival rate at 25 weeks

Answer 15

Viability limit = 24 weeks
At 25 weeks = 50% survival

Without intensive care required = end of trimester (26-27 weeks)

Question 16

Define the features and risks of the third trimester (27-39 weeks) and list the main purposes of this phase

Answer 16

GROWTH (loads, increases by 2 kg)

Maturation of brain, immune system, lungs and digestive tract (BILD)
Problems with these systems if baby is born prematurely
Highest risk to mother during this time
Labour, haemorrhage

Question 17

List the main placental functions

Answer 17

Separation between maternal and fetal system
Exchange nutrients and waste products
Biosynthesis
Immunoregulation of whole of pregnancy
Connection: placenta must anchor the pregnancy in place

Question 18

Identify the main features of the maternal side of the placenta

Answer 18

Pieces of tissue with separation between them (cotyledon) , number of them doesn’t matter for the growth and development of baby
Large cotyledon is in the centre of placenta (2-3cm) and smaller out
The gaps between cotyledon contains maternal tissue = decidua. Usually stays behind after birth
Very strong contact with vascular system on this side

Question 19

Identify the main features of the foetal side of the placenta

Answer 19

Disc shaped structure
The side baby will be facing and the umbilical cord which will connect to the fetus
Blood vessels are carrying nutrients from maternal system to baby insertion point near the centre
Fetal membranes thinner in placenta and surrounds the disc
Umbilica cord is very hard and can cause damage to baby if it gets tangled

Question 20

Describe the vasculature of the placenta

Answer 20

Spiral arteries - provide blood supply to foeto-placental unit

Placental villous trees -Massive surface area

Umbilical vessels - As in lung, vein = oxygenated blood, arteries – deoxygenated blood

Countercurrent flow

Question 21

What occurs in spiral artery remodelling

Answer 21

arteries become wide bore = greater exchange of nutrients

High volume blood supply in trimesters 2 and 3, when infant growth is greatest.

Question 22

How is pregnancy normally “Counted” and why is this system used

Answer 22

The last day of the last menstrual period is used as the basis of pregnancy timing
As this can be identified easily

Question 23

What are the key features of the placenta

Answer 23

Very highly branched structure, provides a large surface area (~11m2).
Very effective for transport of molecules between maternal and fetal circulations.
Anchors the placenta (and baby) securely for 9 months.
Intimate contact between maternal and placenta tissues – immunology

Question 24

What do cytotrophoblasts do in placental development

Answer 24

Cytotrophoblast shell limits blood (oxygen) supply to embryo during early development

Question 25

Explain how the placenta develops

Answer 25

Refer to notes 
1. Implantation 
2. Trophoblast -> CTB, STB
3. STB sends projections for embedding 
4, Lacunae formation 
5. Primary chorionic villi
6. Secondary chorionic villi 
7. Tertiary chorionic villi
8. CTB shell
9. Spiral artery remodelling 
10. Maternal blood flow exposure

Question 26

What is the change in nutrition of the foetus as the placenta develops

Answer 26

Histotrophic nutrition (decidual glands) -> haemotrophic nutrition (maternal vessels)

Question 27

What is the difference between miscarriage and stillbirth

Answer 27

<24 weeks – miscarriage

>24 weeks – stillbirth

Question 28

how are ultrasound imaging and fetal dopplers used in fetal assessment

Answer 28

Foetal monitoring of movement and blood flow (e.g. Ultrasound scans, and doppler USSs) may indicate increased risk but cannot predict
Reduced fetal movements -> increased risk coupled with assessment of the fetal blood flow (doppler ultrasound).