Fetal growth Flashcards
What is normal fetal growth
Three phases
First
-4-20 weeks
-increases in fetal weight,
-due to increase in protein content and DNA content (cellular hyperplasia)
-development of tissues, organs, structures
-simialr weight at 20 week mark across most babies
Second
-20-28 week
- increased in protein and
weight
-gorwth of liver and brain
-lesser increases in fetal DNA content
-hyperplasia and concomitant hypertrophy
Third
-28 weeks
increased fetal protein and weight
-no increase in DNA
-hypertophy
How can we measure fetal growth
-use a growth chart
-tape measure from symphsis pubis to top of fundus (y axis)
-x axis is gestational age
-mark up with cross to work out age
Defintitions
Fetal growth restriction (FGR)
Failure of a fetus to achieve his or her
growth potential
-genetically meant to be bigger, but smth patholgical occured
Small for gestational age (SGA)
Birth weight <10th centile for gestational age
– Centiles are based on local populations
– Can be adjusted for sex, parity, race,
maternal weight and heigh
Large for gestational age (LGA)
Birth weight >90th centile
Low birth weight (LBW)
-birth weight less than a certain threshold
e.g. 2500g
What are the consequences of fetal growth restrictions
pathological process
-may cause perinatal and neonatal death
-LBW babies more likley to die in first year, can suffer with asphyxia, hypoglycermia, hypothermia
-growth origin of adult disease
What is the barker hypothesis
what happens in utero affects you for the rest of your life
-if you suffer from metabolic syndrome, and something alters growth, more likley to have metabolic programming that puts you at risk of metabolic diseases in adult hood
If your mother has impaired nutrition what can that alter
-can alter appetitie centres develop
-can alter kidney response to conditions -> can get hypertension
-more likely defective beta cell function -> can cause insulin defiency
-more likley to have altered adipose tissue, which can lead to obesity
-blood vessles can be altered -> hypertensuin
Get a thrifity phenotyoe
-you try to make the most of every nutrition
-Evolved like this to offer advantage in a “famine environment”
- but moretime when the chld is born they may be in industrialised society
What intergenerational effects are there
Mothers who had a small gestetional age
-more likley to have SGA babies
-increase perinatal mortaloty
Based on rodent models when can we break the intergenerational effects
After undernutrition for 12 generations,
-takes around 3 gen to restore normal fetal growth and development
What can maternal undernutrition have on subsequent generations
ncrease adiposity,
glucose intolerance and cardiovascular risk in F1 and F2 generations
What are the mechanims for transgenerational effects
how does it happen
-may be due to epigenetics via DNA methylation, histone modifcation, micro RNA
In maternal mitochondria
-food restriction can alter
number and function
Directly passed onto to offspring through ova.
epigenetics: heritable changes in gene expression
by mechanisms other than underlying DNA
sequences
What are the causes of LGA
large for gestatioanal age
- Gestational age; pregnancies that go beyond 40 weeks increase incidence
- Fetal sex; male infants tend to weigh more than female infants
- Excessive maternal weight gain and obesity
- Multiparity (more children yoy have the bigger your babies are have 2
- Erythroblastosis fetalis - Hydrops Fetalis
- Genetic disorders of overgrowth (babies express genes like e.g. Beckwith-Wiedemann syndrome, Sotos syndrome)
- Maternal diabetes (the most common cause of pathological overgrowth -> pre-existing or gestational)
maternal diabetes
yiu get increase maternal glucose conc -> glucose corsses placenta -> baby makes for insulin -> they start making more fat
=have bigger abdomen circumferances
What is the pathophysiology behind LGA
matenral diabtes
- Increased maternal glucose concentrations
glucose corsses placenta - Increased fetal insulin concentrations
- Increased fetal growth factors
- babies have bigger abdomens but notmal head circumferance