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Year 2 - RDA LCRS 2 > normal fetal growth > Flashcards

normal fetal growth Flashcards

1
Q

What are the main methods of measuring fetal growth?

A
  • crown rump length

- fetal weight

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2
Q

define fetal growth

A

Increase in mass that occurs between the end of embryonic period and birth

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3
Q

Fetal growth depends on what 2 components:

A
  • Genetic potential
    derived from both parents
    mediated through growth factors eg insulin like growth factors
  • Substrate supply
    essential to achieve genetic potential
    derived from placenta which is dependent upon both uterine and placental vascularity
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4
Q

Normal fetal growth is characterised by 3 subsequent phases:

A
  1. Cellular hyperplasia (start of gestation - 20 wks)
  2. Hyperplasia and hypertrophy (20-28wks)
  3. Hypertrophy alone (28 - last trimester)
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5
Q

Describe the fetal growth velocity with development

weight gain (rate) increases with time

A

14-15 wks: 5g /day
20 wks: 10 g/day
32-34 wks: 30-35g/day
>34 wks: growth rate decreases

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6
Q

What is the significance of the symphysis fundal height?

A

distance over the abdominal wall from the symphysis to the top of the uterus

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7
Q

Why might the SFH be:

a) smaller
b) larger

than normal

A

Smaller: wrong dates
small for gestational age
oligohydramnios
transverse lie

Larger: wrong dates
	molar pregnancy
	multiple gestation
	large for gestational age
	Polyhydramnios
	Maternal obesity
	Fibroids
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8
Q

What are pros and cons of SFH ?

A

pros:
Simple
Inexpensive

cons:
Low detection rate: 50-86%
Great inter-operator variability
Influenced by a number of factors (BMI, fetal lie, amniotic fluid, fibroids)

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9
Q

Why is dating the pregnancy accurately important?

A

SGA or LGA confusion
Inappropriate inductions
Steroids in preterm delivery

–> All pregnancies should be dated by CRL except IVF pregnancies

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10
Q

Why would dating by LMP be inaccurate?

A

women may have = (irregular periods; abnormal bleeding; oral contraceptives, breastfeeding)

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11
Q

NOTE: All pregnancies should be dated by CRL (crown rump length) except IVF pregnancies

A

-

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12
Q

When is head circumference used to date pregnancy?

A

if first scan is done after 14 weeks (CRL>84mm)

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13
Q

What are maternal factors influencing fetal growth?

A

Maternal factors:

  • Poverty
  • Age (very young / old)
  • Drug use
  • Weight
  • Disease
  • hypertension
  • diabetes
  • coagulopathy
  • Smoking and nicotine
  • Alcohol
  • Diet
  • Prenatal depression
  • Environmental toxins
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14
Q

What are some feto-placental factor influencing fetal growth?

A

Feto-placental

  • Genotype – genetic potential
  • Gender (B>G)
  • Hormones
    Previous pregnancy
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15
Q

What are some feto-placental factor influencing fetal growth?

A

Feto-placental

  • Genotype – genetic potential
  • Gender (Boys > Girl)
  • Hormones
    Previous pregnancy
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16
Q

The customised standard defines the individual fetal growth potential by three underlying principles:

  1. Adjusted for maternal constitutional variation
    e. g maternal height, weight, ethnicity, parity
  2. Optimised by presenting a standard free from pathological factors such as diabetes and smoking
  3. Based on fetal weight curves derived from normal pregnancies
A

-

17
Q

what is the significance of obstertric ultrasound examination?

A

Assessment of fetal “wellness” not just size

Looking at trends in growth

Predicting fetal metabolic compromise

Anticipating the need to deliver prematurely

18
Q

define
SGA
FGR

A

SGA: Small for Gestational Age

  • birth weight < 10th centile
  • -> growth at the 10th or less percentile for weight of all fetuses at that gestational age

FGR: Fetal growth restriction
- Failure of the fetus to achieve its predetermined growth potential for various reasons

19
Q

CHOOSIGN CENTILES
When choosing which centile to use, a balance between sensitivity and specificity is being made – the tenth centile is most sensitive and the third centile is most specific.

A

-

20
Q

What are the short term and long term sequelae of FGR?

A
  • Intrauterine growth restriction = most common factor identified in stillborn babies.

increased risk of IUGR and intrauterine death (IUD) in mother’s subsequent pregnancy.

21
Q

What are some problems of LBW / FGR / Prematurity?

A 
Short term      Respiratory distress
			Intraventricular haemorrhage
			Sepsis
			Hypoglycaemia
			Necrotising enterocolitis
			Jaundice
			Electrolyte imbalance

Medium term Respiratory problems
Developmental delay
Special needs schooling

Long term Fetal programming

22
Q

What are main causes of Small for Gestation Age (SGA) ?

A
  • dating problem
  • normal
  • fetal problem (e.g fetal abnormality / fetal infection)
  • placental insufficiency
23
Q

What are factors associated with FGR + SGA fetus ?

A 
- Maternal medical factors 
•Chronic hypertension
•Connective tissue disease
•Severe chronic infection
•Diabetes mellitus
•Anaemia
•Uterine abnormalities
•Maternal malignancy
•Pre-eclampsia
•Thrombophilic defects
- Maternal behavioural factors
•Smoking
•Low booking weight (<50 kg)
•Poor nutrition
•Age <16 or >35 years at delivery
•Alcohol
•Drugs
•High altitude
•Social deprivation 
- Fetal factors 
•Multiple pregnancy
•Structural abnormality
•Chromosomal abnormalities
•Intrauterine (congenital) infection
•Inborn errors of metabolism 
- Placental factors
•Impaired trophoblast invasion
•Partial abruption or infarction
•Chorioamnionitis
•Placental cysts
•Placenta praevia
24
Q

NOTE: The first half of pregnancy = time of
preparation for the demands of rapid fetal
growth in the second half

Alterations in maternal physiology facilitate transfer of nutrients to the fetus

A

-

25
Q

When is the period of placentation?

A

10-12 weeks

- rapid early growth –> prepares way fro fetal growth

26
Q

Why is the placenta important ?

A
  • Maintains immunological distance between mother and fetus
  • Special endocrine organ: produces protein-peptides and steroid hormones
  • -> also functions as a “transient hypothalamo-pituitary-gonadal axis”
  • Responsible for exchange of nutrients, gases & metabolic waste products between maternal and fetal circulation
27
Q

What is pre-eclampsia ?

A

Multisystem disease that usually manifests as hypertension and proteinuria

causes in maternal women:

  • Hypertension
  • Oedema
  • Proteinuria
28
Q

Which fetuses need growth monitoring?

A 
Bad Obstetric History 
	Previous maternal hypertension
	Previous FGR
	Stillbirth 
	Placental Abruption

Concerns in index pregnancy
Abnormal serum biochemistry PAPP-A <0.3 MoM
Reduced symphysis fundal height
Maternal systemic disease e.g. hypertension, renal, coagulation
Antepartum haemorrhage

29
Q

Sequence of events in FGR

A

there will be

  • reduced FM
  • decrease in middle cerebral artery blood flow
  • increase in ductus venous blood flow –> IUD
30
Q

NOTE: Increased impedance in the umbilical arteries becomes evident –> only when at least 60% of the placental vascular bed is obliterated

A

-

31
Q

What might be the effect of hypoxia on the fetus?

A

a) Aortic body chemoreceptor Stimulation
- -> causes Redistribution of cardiac output

–> Increased flow to:
Brain
Heart
Adrenals

Decreased flow to:
Lungs
Kidneys
Gut

b) CNS dysfunction
Poor tone
Altered breathing
Altered movement patterns
Changes in heart rate patterns
32
Q

fetal movement counting

A
  • using Cardiff kick chart
  • Mothers record the time taken each day to feel ten fetal movements.
  • -> reduction / absence in fetal movements,
  • -> need cardiotocography + ultrasound assessment of the fetus
33
Q

How would you Deliver in pregnancies complicated by FGR

A

Corticosteriods should be administered (if not already given) at gestations < 36 weeks in orderto improve neonatal wellbeing

  • Aim to deliver when ≥28 weeks and / or ≥500g
    Caesarean section for compromised fetuses
34
Q

The mode of delivery of FGR will depend upon:

A 
Gestation of the pregnancy
Condition of the pregnancy
State of the cervix
Presentation of the fetus
Other factors: oligohydramnios
 labour may be poorly tolerated due to cord compression
35
Q

compare between Early IUGR and Late IUGR

A

early IUGR

  • Low incidence 1%
  • Highly correlated to maternal disease (preeclampisa)
  • Difficult to manage
  • Balancing risks of severe prematurity and morbidity with risk of in utero death

Late IUGR

  • More common 5-7%
  • Rarely correlated to pre-eclampisa
  • Difficult to differentiate from constitutionally SGA
  • Easy to manage: deliver
36
Q

Fetal growth restriction is NOT associated with:

A High resistance umbilical artery Doppler readings
B Preterm delivery
C Increased risk of delivery by Caesarean section
D Neonatal hyperglycaemia
E Neonatal necrotising enterocolitis

A

D Neonatal hyperglycaemia

Year 2 - RDA LCRS 2 (8 decks)

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