Small babies Flashcards
What characterizes the embryonic period in terms of development?
Intense morphogenesis and organogenesis, but very little absolute growth (except for placenta).
When does fetal growth and weight gain accelerate?
During the fetal period.
What is differential growth during fetal development?
- Early: Crown-Rump Length (CRL) grows steadily.
- Mid-late: Weight gain accelerates due to protein (early) and fat (late) deposition.
What type of tissue deposition dominates in the late fetal period?
Adipose (fat) deposition.
what is crown rump length?
It measures the length of the fetus from the top of the head to the bottom of the buttocks - estimates gestational age
What is the CRL at 9 weeks?
5 cm
What is the CRL at 12 weeks?
8.5 cm
What is the CRL at 20 weeks?
19 cm
What is the CRL at 28 weeks?
28 cm
What is the CRL at 36 weeks?
36 cm
How do body proportions change during development?
- At 9 weeks, head = ~½ of CRL
- Later, body and lower limbs grow faster than the head
Which hormones are essential for fetal growth?
Insulin
IGF-I (nutrient dependent; dominates in T2 and T3)
IGF-II (nutrient independent; dominates in T1)
Leptin (placental)
EGF, TGF-α
Which hormone dominates early fetal growth?
IGF-II
What hormone dominates later fetal growth?
IGF-I
What are two types of growth restriction caused by malnutrition?
Symmetrical and asymmetrical growth restriction.
What is the “Developmental Origins of Health and Disease” hypothesis?
Suggests that fetal nutrition and hormone environment can influence adult health and disease risk.
What is considered average birth weight?
3500 g
What birth weight indicates growth restriction?
< 2500 g
What is macrosomia?
Birth weight > 4500 g, often due to maternal diabetes.
What are non-pathological influences on birth weight?
Placental (e.g., low PAPP-A), fetal (e.g., echogenic bowel), maternal (e.g., BMI extremes, smoking, hypertension).
Why is accurate dating important?
To differentiate between prematurity, constitutional smallness, and growth restriction
What is the best time to date a pregnancy using CRL?
Between 6–13 weeks; specifically 11+2 to 14+1 weeks for the first scan.
What other measurements are used after the first trimester to estimate gestational age?
Head circumference and femur length (from 13 weeks onwards).
What are the 4 components of fetal wellbeing assessment?
Maternal perception of fetal movements
Biochemical markers
Symphysis-fundal height (SFH)
Ultrasound scan (USS)
Name 4 biochemical markers of fetal wellbeing.
hCG, hPL, estriol, alpha-fetoprotein.
When is the uterus palpable at the umbilicus?
Around 22 weeks gestation.
What SFH finding indicates concern for FGR?
<10th centile or serial measurements lower than expected.
What does the first trimester scan assess?
Crown-rump length (dating)
Viability
Chorionicity
Nuchal translucency
Why is head circumference useful in dating?
It is less affected by fetal head shape.
What does abdominal circumference (AC) and femur length (FL) assess?
Growth monitoring and anomaly detection, especially when combined with HC.
What change is seen in normal umbilical artery Doppler over time?
Progressive increase in diastolic flow, decreasing resistance.
What are stages of worsening Doppler findings in the umbilical artery?
A = normal
B = reduced diastolic flow
C = absent end-diastolic flow
D = reversed end-diastolic flow
What do absent/reversed end-diastolic flows indicate?
Fetal hypoxia; reversed flow is a late and concerning sign.
What causes abnormal uterine artery flow?
Inadequate spiral artery remodelling — high resistance, low flow.
What is the decidual reaction?
Transformation of endometrium to decidua to control trophoblast invasion.
What happens if the decidual reaction is suboptimal?
Poor placentation, leading to pre-eclampsia, FGR, and other complications.
Name fetal factors for FGR.
Chromosomal abnormalities
Single gene disorders
Epigenetic defects (e.g., methylation disorders)
Infections (TORCH)
Name maternal risk factors for FGR. 8
Hypertension, renal/cardiovascular disease
Uterine malformations, gastric bypass
Smoking, alcohol, drugs, eating disorders
Name placental factors for FGR.
Infarction
Abruption
Single umbilical artery
Placental insufficiency
What are the effects of utero-placental compromise?
Fetal renal insufficiency
Reduced amniotic fluid
Growth restriction
Fetal hypoxia
When does symmetrical growth restriction typically occur?
Early in pregnancy during the hyperplasia phase.
What is the Barker Hypothesis?
Poor fetal growth leads to permanent changes in metabolism, increasing risk of adult diseases like metabolic syndrome in later life.
What does TORCH stand for?
T – Toxoplasmosis
O – Other (commonly includes syphilis, varicella zoster, parvovirus B19, and HIV)
R – Rubella
C – Cytomegalovirus (CMV)
H – Herpes simplex virus (HSV)
