L13: Fetal Growth Flashcards
What are the phases of foetal development?
Cellular hyperplasia - 4-20 wks (increase in foetal protein, weight + DNA)
Hyperplasia + concomitant hypertrophy (20-28 wks) - less increase in DNA
Hypertrophy - 28 wks - term, only increase in protein + weight
What is the ponderal index?
Baby BMI
What is the MAC/HC ratio?
Mid arm circum/head circum ration
How many births does foetal growth restriction affect? (Both IUGR & SGA)
3-10%
Consequences of foetal growth restriction
More likely to die in first yr of life + suffer from neonatal problems
Basis of foetal programming
Plastic neuroendocrine system that can adapt to different nutrient states that continues throughout life
What can foetal programming increase risk of?
Obesity, type 2 diabetes, BP, stroke, HF
Mostly secondary to changes in growth, metabolism + vasculature
Mother born SGA are more likely to?
Have SGA babies w higher perinatal mortality
Definite of perinatal mortality
Dying from 24 wks of pregnancy to 28 days of life
What are the mechanisms of train generational effects of foetal programming
Epigenetics & inheritance of maternal mitochondria
Food restriction alters number + function of mitochondria
What is macrosomia?
Birth weight > 4500g - clinical opposite to IUGR
Causes of macrosomia
Greater gestational age, Male, maternal obesity, multiparity, maternal diabetes pre existing, erythroblastosis fetalis
What is erythroblastosis fetalis?
Foetal has HF —> fluid build up causing macrosomia
Pathophysiology of macrosomia
Increased maternal glucose —> increased foetal insulin —> increased IGF
What regulates foetal growth?
Combination of substrate availability + endocrine/paracrine signalling (mainly IGF-1 + 2)
What are the maternal factors affecting growth?
Ethnicity, BM1, Drugs esp cigarettes, alcohol, nutrition, maternal hypoxia, anaemia, chronic disease
Why is maternal nutrition not that significant unless extreme under nutrition/placental insufficiency?
Placenta acts as moderator so any takes what it need from mother
When in gestation does growth restriction occur?
Late gestation
What are the foetal factors affecting growth?
Genetic factors e.g. Edwards, Patau’s, downs
Growth factors e.g. IGF, thyroxine
Congenital infection e.g. cytomegalovirus, toxoplasmosis, rubella
What are the placental factors affecting growth?
Primary - errors in placentation+ EVT invasion in 1st trimester, often autoimmune
Secondary - hypertension, CKD, vasculitis, pro thrombotic disease, also due to twins sharing placenta
How with IUGR change Doppler flow?
Diastolic notching - low flow in umbilical arteries during diastole
Raised RI
What is the most common factor affecting foetal growth?
Placental factors
What is symmetrical IUGR?
Overall small baby due to early growth insult e.g. virus, chromosomal abnormality
Disruption in cell hyperplasia stage if growth (4-20wks)
When is doppler ultrasound done?
~ 6 + 20wks but only for high risk women
What is asymmetrical IUGR?
Preserved growth of head as prioritising brain development
Decreased glycogen stores also decrease abdo circumference
What can be used to assess fetal growth?
Symphsio fundal height
Ultrasound (look at head + abdo circumference)
When is ultrasound scanning done in pregnancy?
12 wk - confirm due date, ch3ck developmental/genetic issues?
18-22 wks - know sex of baby + check for abnormalities
What can be used to check foetal wellbeing short & long term?
Short - cardiotocograph (monitor fetal HR using transducer + uterine contractions), baby must be delivered immediately if there’s problem
Long- Doppler ultrasound, if there’s a problem, MCA + ductus venous can also be checked if flow is affecting brain/heart
What may growth restriction —> lower amniotic volume?
Blood diverted away from kidneys to brain so lower urine vol
Why does gestational diabetes occur?
Pregnancy is a state of insulin resistance due to hormonal, inflammatory changes (e,g. Release of placenta growth hormone)
Resistance increase with higher gestation
What is the high risk group screened for GD?
Previous GD, history of insulin resistance, family history, PCOs, raised BMI, previous big baby, south Asian/black,
Screen immediately if: significant glycosuria, macrosomia, polyhydaminos
What are the maternal complications of gestational diabetes?
Pre eclampsia, pre term labour, instrumental delivery/c section, diabetes continues
What are the foetal consequences of gestational diabetes?
Macrosomia —> shoulder dystocia
Polyhydaminos
Perinatal mortality due to hypoglycaemia after birth, jaundice, polycythaemia, hypocalcaemia
Post natal management for gestational diabetes?
Slowly waning off insulin better
Encourage breastfeeding
Fasting glucose test done in 6 wks time/ HbA1C 3 months later to check if there’s still diabetes
Management of GD during Pregnancy?
Diet restriction, metformin, insulin last - regular finger prick tests w strict glucose control, ultrasound done every 3-4 wks, foetal heart beat
