Pregnancy Flashcards
1
Q
What does ‘6 weeks pregnant’ mean in terms of gestational age and embryonic age?
A
Gestational age = 6 weeks (since LMP)
Embryonic age = 4 weeks (since conception)
2
Q
What is the embryonic period defined as?
A
Up to 8 weeks
3
Q
What is the fetal period defined as?
A
After 8 weeks
4
Q
When does implantation begin?
A
Day 6/7 (after conception)
5
Q
When is implantation complete?
A
Day 10
6
Q
What is the ‘implantation window’?
A
The period in which implantation must occur (between days 20 and 24 of normal menstrual cycle)
7
Q
What is the essential condition for implantation?
A
Low oxygen tension (remains until 16 weeks)
8
Q
What causes the low oxygen tension in the first 16 weeks?
A
Trophoblast cells migrate into the spiral arteries and plug them
This blocks maternal blood flow to the placenta
9
Q
What kind of nutrition does the foetus rely on for the first 16 weeks before the placenta development is complete?
A
Anoxic histiotrophic nutrition (diffusion)
10
Q
What are the 3 stages of implantation?
A
- Apposition
- Attachment
- Penetration
11
Q
What occurs during apposition?
A
Progesterone gets endometrium ready for fetus.
Becomes rich in glands, capillaries and stroma
12
Q
What occurs during attachment?
A
Pinopodes from endometrium and microvilli on trophoblast help attachment
13
Q
What molecules does penetration during implantation involve?
A
Prostaglandins (mediated by COX1 and COX2)
14
Q
What do the uterine glands produce?
A
Lots of hormones that stimulate growth of embryo, e.g. VEGF, hCG.
15
Q
Which 2 layers does the outer cell mass form?
A
- Synctiotrophoblast (outer layer, multinucleated)
2. Cytotrophoblast (inner layer, mononuclear)
16
Q
Where is hCG produced?
A
Synctiotrophoblast
17
Q
Where does hCG act?
A
On corpus luteum (positive feedback) to sustain progesterone levels
–> prevents menstruation and promotes decidualisation
18
Q
What is the relationship between uterine microbiome and implantation?
A
Microbiome affects implantation
Recurrent miscarriage lady likely to have abnormal uterine microbiome (more anaerobic bacteria)
19
Q
How can pre-eclampsia be diagnosed?
A
Doppler screening of the uterine artery
20
Q
What are the risk factors for pre-eclampsia?
A
- previous history
- multiple gestation (twins etc)
- chronic hypertension/ diabetes etc
- obesity
- family history
- first pregnancy
21
Q
What prophylaxis for pre-eclampsia is given if patient is high risk?
A
Aspirin should be given in first trimester
22
Q
Which molecule is a good diagnostic indicator of pre-eclampsia?
A
Placental growth factor
23
Q
What causes pre-eclampsia?
A
Placenta does not develop properly due to blood vessels supplying it
24
Q
When do the chorionic villi appear?
A
At the end of the second week
25
How do the placental villi form/
Primary villus --> secondary villus --> tertiary villus
26
What kinds of villi make up the outer placenta?
Chorion lavae and chorion frondosum
27
What is the final form of the placenta made up of?
Decidual plate (maternal portion) and chorion frondosum (fetal portion)
28
What does the placenta regress to form?
Discoid placenta (16 weeks)
29
Where should placenta be at 38 weeks?
At top of uterus otherwise it causes huge haemorrhage
30
Name 3 placental complications.
1. Low lying placenta
2. Retained placenta
3. Placental abruption (premature separation of the placenta from the uterus)
31
What are the main functions of the placenta?
Respiratory organ
Nutrient transfer
Excretion of fetal waste products
Hormone synthesis
32
What are the 2 stages of the formation of the maternal circulation?
1. Differentiation of endometrium into decidua
| 2. Transformation of uterine spiral arteries
33
What is the function of the uterine NK cells?
Alter structure of spiral arteries/ open them
34
What happens if the opening of the spiral arteries fails?
Fetal growth restriction
| or pre-eclampsia
35
What happens if the spiral arteries open too early?
Implantation failure
Miscarriage
(also oxidative stress causing congenital malformations)
36
At what point in pregnancy does the placenta not undergo any more anatomical changes?
End of 4th month
37
What is the difference between monozygotic and dizygotic twins?
Monozygotic - one egg, identical
| Dizygotic - two eggs, non-identical
38
What are the types of monozygotic twinning?
1. Dichorionic (2 placentas) - cleavage before implantation
2. Monochorionic, diamniotic - cleavage day 6-8
3. Monoamniotic - cleavage after day 8
39
How do conjoined twins arise?
Cleavage during embryogenesis (rare)
40
What increases the chances of monozygotic twins occurring?
Assisted conception like IVF
41
Are dizygotic twins mono or di chorionic?
All dichorionic
42
What are risk factors for having twins?
```
Age over 35 - FSH rises with age and causes double ovulation
Family history
Previous multiple birth
Black ethnicity
Increased BMI
Smoking
Pill
```
43
What is a sacrococcygeal teratoma?
Remnant of the primitive streak
| Can take large blood supply and cause fetal heart faiulre
44
What switch in the placental circulation occurs at 12 weeks?
Switch from histiotrophic nutrition to haemotrophic nutrition (large rise in intraplacental oxygen)
45
What is the job of the two umbilical arteries?
Carry deoxygenated blood from fetus to placenta
46
What is the job of the umbilical vein?
Carries oxygenated blood from placenta to fetus
47
What is special about the umbilical vein?
ONLY time a vein carries oxygenated blood
48
How are the cells of the synctiotrophoblast specialised?
Brush border
| Lots of mitochondria
49
Why is the fetal pO2 always low?
Protect from oxidative stress and enable easy transfer of oxygen from mother to baby
50
What is a common cause of fetal growth restriction?
Defects in amino acid transporters across the placenta
51
What regulates the growth and development of the alimentary tract?
Gastrin, motion and somatostatin are ingested by the fetus
52
When does the fetus start making insulin?
9 weeks
53
Why do all pregnant women become a bit diabetic?
Increase in their blood glucose to help transfer of glucose to the baby
54
What is gestational diabetes?
Diabetes during pregnancy - more common in pre-diabetic women
55
What is macrosomia?
When the baby is overweight at birth (associated with maternal obesity and diabetes)
56
What are the complications of macrosomia?
Labour issues
Increased risk of still birth
C section often needed
57
How is fluid balance maintained in the fetus?
Mostly by the placenta
| Fetus also has a functional kidney that makes dilute urine (ADH is immature)
58
What is Oligohydramnios?
Too little amniotic fluid
59
What is Polyhydramnios?
Too much amniotic fluid
60
What is amniotic fluid made up of?
```
Urine
Amniotic membrane secretions
Fetal lung secretions
Salivary secretions
Fetal epithelial cells
```
61
How is fetal heart rate mainly controlled?
Through the autonomic nervous system (parasympathetic/ vagal tone dominates)
62
What are 4 adaptations of the fetal circulation seeing as it does not go to the lungs?
1. Umbilical vein/arteries
2. Ductus venosus (blood bypasses liver)
3. Foramen ovale (blood from R heart to L heart)
4. Ductus arteriosus
63
What is the fetal response to hypoxia?
```
Heart rate falls
More resistance in umbilical artery
Less resistance to middle cerebral artery
Increased blood flow to heart
Decreased blood flow to kidneys
```
64
What causes the foramen ovale and ductus arteriosus to close?
At delivery, cord occlusion decreases right atrial pressure
Inspiration causes vasodilation of pulmonary artery
Increased arterial pO2
65
Which molecules delay ductus arteriosus closure?
Prostaglandin and prostacyclin
66
What drugs accelerate closure of the ductus arteriosus?
NSAIDs
67
How are the fetus' lungs cleared of their liquid?
1. Physical force during labour
2. Activation of ENaC channels
3. Transpulmonary hydrostatic pressure gradient
68
What do some babies need to help them take their first breath?
Cold shock
69
When does pulmonary surfactant start to be secreted?
30 weeks
70
What is given to a woman with a pre-term baby to stimulate surfactant production?
Glucocorticoid
| and give baby artificial surfactant when born
71
What can happen if a baby is not treated to stimulate surfactant production if premature?
Neonatal respiratory distress syndrome
72
What is the function of pulmonary surfactant?
Reduces surface tension
Increases lung compliance
Stabilises the lung
73
What occurs late in pregnancy to stimulate surfactant production?
Surge in cortisol
74
When does the switch from HbF to HbA begin?
28 weeks
75
What happens to plasma volume during pregnancy?
Increases
| --> RAAS increases
76
What happens to red cell mass during pregnancy?
Increases
| - being anaemic is v bad
77
What happens to the haematocrit during pregnancy?
Decreases
| - plasma volume goes up more than red cell volume (diluted)
78
Why is physiological anaemia normal during pregnancy?
Plasma volume increases more than red cell volume
79
Why is folate important in pregnancy?
Important in DNA methylation and synthesis
| Needed in early pregnancy to reduce neural tube defects
80
What are the 3 sources of steroids in pregnancy?
Placenta
Fetus
Mother
81
Where is progesterone produced during pregnancy?
By corpus luteum then placenta
82
What effects does progesterone have on fetal antigen responses and tidal volume?
Decreased response to fetal antigens
| Increased tidal volume
83
What does human placental lactogen do?
Important for maternal lipolysis and anti-insulin action
84
What does leptin do in pregnancy?
Women become leptin restistant
| Stimulates placental amino acid/fatty acid transport
85
Are LH and FSH detectable during pregnancy?
No
86
What effect does pregnancy have on BP?
Decreases in first 2 trimesters
| Increases at end of pregnancy
87
What happens to CO and O2 consumption in pregnancy?
Increase
88
What happens to peripheral resistance in pregnancy?
Decreases due to increased NO synthesis etc
89
What happens to the mother's kidneys during pregnancy?
GFR increases by 40-65%
| Urination freq increases and urinary statis causes UTIs
90
Why are C section babies more likely to become obese?
Do not pick up vaginal microbiome during delivery
91
What feature of breathing is unchanged by pregnancy?
Respiratory rate
92
Do pregnant women have an acidosis or alkalosis?
Respiratory alkalosis
| Low pCo2, low bicarb
93
What is the relationship between pregnancy and DVT?
DVT more likely due to low grade increase in coagulability
| should go on heparin if high risk
94
What happens to the GI tract during pregnancy?
Smooth muscle relaxes
| So constipation
95
When should morning sickness due to hCG beta stop?
15 weeks
96
What is the main danger to maternal health during pregnancy?
Pregnancy symptoms can mask pathology
97
What is the biggest cause of maternal mortality?
Cardiac problems
98
What are the current antenatal screening policies in the UK?
```
Haemoglobinopathy
Infectious diseases
Chromosomal abnormalities
Fetal anomalies
Pre-eclampsia
```
99
What are downsides to screening?
False positives
Harm from screening
Cost
100
What are important disease characteristics for screening?
Important health problem
Recognisable early phase
Treatment exists
101
How are pregnant women screened for sickle cell?
Only high risk women screened
| Can offer CVS/amniocentesis
102
How are pregnant women screened for thalassemia?
All women screened at 10 weeks by blood test
103
Which infectious diseases are screened for?
HIV
Hep B
Syphilis
104
How are chromosomal abnormalities screened for?
Combined test in 1st trimester
105
What is the fetal anomaly scan?
20 week scan done by US
106
What are the 3 stages of fetal growth?
1. Hyperplasia
2. Hyperplasia and hypertrophy
3. Hypertrophy
107
Which trimester does most fetal weight gain occur?
Third
108
How is fetal growth measured?
Crown-rump length (CRL)
109
What is the first scan for at 12 weeks?
Viability
Single/multiple pregnancy
Crown rump length (dates the pregnancy)
110
What is the second scan fro at 20 weeks?
Routine anomaly scan
Assessing fetal growth
Fetal anomalies
Location of placenta
111
How is fetal growth assessed?
Head circumference
Bi-parietal diameter
Abdominal circumference
Femur length (gives estimated fetal weight)
112
What is the symphysial fundal height? (SFH)
Measure of bump using a tape measure
| Gives gestational age plus or minus 2cm
113
What should the SFH be at 20 weeks?
Umbilicus
114
What is the amniotic fluid index? (AFI)
Amount of amniotic fluid on US (8-18 is normal)
115
What is fetal growth restriction?
Placenta may not be working properly/problem with mother
Pathological
Increases risk of perinatal complications (unlike SGA babies)
116
How can the chances of stillbirth be reduced?
1. Reduce smoking in pregnancy
2. Risk assessment for FGR
3. Raise awareness of reduced fetal movement
4. Effective fetal monitoring during labour
117
What does low levels of PAPP-A at 1st trimester combined screen indicate?
Poor placentation
- increased risk of SGA/pre-eclampsia
Give aspirin
118
What are maternal risk factors for SGA?
Diabetes
Hypertension
Active lupus
Sickle cell disease
119
What are fetal risk factors for SGA?
Multiple pregnancies
Fetal structural/chromosomal abnormality
Fetal infection
120
Are monochorionic or dichorionic twins more high risk?
Monochorionic - should be scanned every 2 weeks
121
How is LGA/macrosomia defined?
Birth weight greater than 4kg
122
What are risk factors for LGA?
Large parents, esp mother BMI
Previous LGA baby
Diabetes
123
What are complications of an LGA birth?
Shoulder dystocia
| Perineal trauma/PPH in mother
124
What is different about first aid of a pregnant women post 20 weeks?
If collapsed sit her up
| Take baby out if mother has cardiac arrest (helps resuscitation of mum)
125
Which scan is not advised during pregnancy?
Abdominal/lumbar sacral spine X ray
