L16: Fetal Growth Flashcards
How many phases of fetal growth and development are there
3
What are the 3 phases called
Cellular hyperplasia
Hyperplasia and commitent hypertrophy
Hypertrophy
What occurs in the first phase cellular hyperplasia
Increase in fetal weight
Increase in protein content
DNA content
What occurs in hyperplasia and concomitent hypertrophy
Increase in protein
Increase in fetal weight
Lesser increase in fetal DNA
What occurs in hypertrophy
Increase in fetal protein
Increase in fetal weight
No increase in DNA
What does fetal growth restriction mean
A failure of a fetus to achieve his/her growth potential
What does small for gestational age (SGA) mean
Babies that are less than the 10th percentile but baby is healthy i.e has no pathological processes that made him small
What is large for gestational age (FGA) mean
Babies weight above the 90th percentile
What does low birth weight mean
Birth weight less than a certain threshold e.g 2.5kg
What are the neonatal indices
Skinfold thickness
Head circumference to abdominal circumference ratio
Ponder all index
What is fetal growth restriction a significant cause of
Peri-natal morbidity and mortality
What are the morbidity complications for fetal growth restriction
Hypoglycaemia
Hypothermia
Birth asphyxia
What can being born with fetal growth restriction cause in the future
Adult disease
What is the hypothesis known as that suggests being born with fetal growth restriction results in adult disease
Barker hypothesis
What type of adult disease can occur in FGR
Diabetes
Metabolic syndrome
What does adult disease in fgr occur as a result of
Secondary changes in growth, metabolism, vasculature i.e thrift phenotype whereby they adapt to cope with reduced nutrient supply but this adaption remains in adulthood
What are mothers who are born small most likely to have
SGA babies
Increased perinatal mortality
What are the mechanims responsible for inner-generational effects
Epigenetics mechanims e.g DNA methylation Histone modification Micro RNA Or maternal mitochondrial inheritance
What Is macrosomia
Birth weight greater than 4.5kg
What can LGA be caused by
Pregnancy above 40 weeks
Male infants tend to weigh more
Excessive maternal weight gain
Obesity in the mother
Genetic disorders e.g beckwith weidemann
Maternal gestational diabetes or pre-existing diabetes
What is the pathophysiology for diabetes causing microsomnia
Increased maternal glucose which crosses the placenta
Increased fetal insulin conc
Increased fetal growth factors
What is the barker hypothesis for FGA babies
Babies that have an increase risk of diabetes and metabolic syndrome in adult hood
What is growth regulation controlled by
Genetic
Environmental; maternal, fetal, placental factors
What is required for successful placentation for growth regulation
Substrate availability
Endocrine/paracrine signalling
IGF1 and IGF2 (major stimulus)
What are the maternal factors that can affect grwoth
Ethnicity
Maternal BMI: obesity increased risk for FGA, malnutrition increases risk for FGR
Drugs: drugs of abuse
Nutrition: vitamin d, folic acid and balanced diet
Maternal hypoxia: cyanotic heart disease, chronic respiratory disease, high altitude
What are the fetal factors that are involved in growth
Genome- chromosomal disorders
Growth factors- insulin like growth factors
Congenital infection: rubella
What are the 2 categories of placental factors for growth regulation
Primary placental factors
Secondary placental factors
What are the primary placental factors involved in growth regulation
Abnormal placenta structure or function e.g abnormal chord insertion
What are the secondary placental factors
maternal factors that affect the placenta: Hypertension Chronic renal disease Vasculitis Prothrombic disease
What occurs in pre-eclampsia
1) There is insufficient invasion of EVT into the decidua and remodelling
2) this gives high resistance and low blood flow to the placenta
What does pre-eclampsia change
Doppler indices
When there is uteroplacental insufficiency what is the head circumference and abdominal circumference like
Head circumference maintained
Abdominal circumference decreased
What does this assymetrical FGR represent
Fetal growth pathology
What does a symmetrical pattern of IUGR show as
Head circumfernce and abdominal circumference grow but at a slow speed
What does a symmetrical IUGR most likely to represent
Early growth insult Chromosomal disorder Viral infection Disrupted growth processed Or Normal growth
How is fetal growth assessment carried out
Symphysis-fundal height
Ultrasound - if the symphysio-fundal height is low
What is the symphysis fundal height
A measurement from the pubic symphysis to the top of the fundus measured in cm
Once a fetus is assessed as SGA how do we monitor fetal well being
Cardiotocograph: measured fetal heart rate and metal urine activity
Umbilical artery doppler
What are the risk factors for SGA
Maternal age 40+ Previous eclampsia Lowe maternal weight gain Previous SGA baby Previous still birth
What is gestational diabetes defined as
Glucose intolerance with its onset during pregnancy
What are the pre-existing risks for gestational diabetes
Women with:
- pancreatic B cell dysfunction
- chronic insulin resistance
When are women screened for gestational diabetes if there is a past history of GDM or glucose intolerance
Week 16-18
When are woman screening in 24-26 weeks
If there is: Family history of diabetes PCOS BMI greater than 30 Asian, black or Middle Eastern ethnicity Previous macrosomia Previous unexplained still birth On steroids
When are woman screened urgently for gestational diabetes
If there is evidence of polyhyramnios, macrosomia or significant glycosuria
What are the screening methods for gestational diabetes
- Oral glucose tolerance test: overnight fast then 75g glucose load, test 2 hours later
- Random blood glucose testing after 36+ weeks
What are the maternal complications for gestational diabetes
Pre-eclampsia
Caesarean section
Diabetes in later life
Pre term labour
What are the fetal compliations for gestationla diabetes
Macrosomia Shoulder dystocia (shoulders become stuck under the pubic symphysis) Polyhydroaminos Jaundice Hypocalcemia Neonatal hypoglycaemia Polycythemia
What are the medical management for gestational diabetes
Diet restriction
Metformin
Insulin
What is the obstetric management for gestational diabetes
Regular growth scans
Regular bone marrow monitoring
Deliver around 38 weeks
Offer glucose intolerance test 6 weeks post natal to identify T2M
