Fetal Growth Flashcards
Define fetal growth
The increase in mass that occurs between the end of the embryonic period and birth
What parameters are used to estimate fetal weight?
Biparietal diameter (BPD), Head circumference (HC), abdominal circumference (AC), Femur length (FL).
Why are USS used in pregnancy?
Main role is to assess the wellbeing of the fetus. Assessing growth trends. Predicting the need for premature delivery. Date a pregnancy
What other method can be used to assess fetal growth? (other than USS)
Symphysis fundal height. ( palpate abdomen to find the pubic symphysis and top of the uterus).
Name 3 factors that can mean an inaccurate EWF using symphysis fundal height.
Underestimation- wrong date of last period, Small for gestational age, oligohydramines, baby lying horizontally.
overestimation- wrong date for last period, multiple preganacies, large gestational age, polyhydramines, high BMI mother, fibroids.
Define SGA
Birth weight <10th centile
What maternal factors influence foetal growth?
Economic status. Age (<16 and >35), Abnormal BMI, smoking, alcohol, diet, anaemia, hypertension, depression, illness/chronic disease, drugs and toxins.
In general is the first or second child larger?
The second child.
What cellular changes normally occur during the course of gestation?
Week 4-20= hyperplasia
week 20-28= hyperplasia and hypertrophy
week 28-40= hypertrophy dominates
What fetal hormones are involved in regulating fetal growth and development?
Cortisol, Thyroxine, insulin and pituitary growth hormone
What hormones are responsible for tissue differentiation?
Cortisol and thyroxine (is also responsible for accretion, which is the increasin in number of layers of cells)
Define IGUR
Failure of an infant to achieve its predeterimed genetic potential for a variety of reasons.
Why does IGUR usually develope in the 2nd and 3rd trimesters?
As this is when the majority of fetal growth occurs and influencing factors have the biggest impact.
what is the role of fetal insulin?
Modifies IGF expression IGF1–> IGF2, increases mitotic drive and increases tissue availabilty for accretion
Name 2 fetal factors impacting fetal growth
Multiple preganacies, structural abnormalities, genotype, gender and chromosomal abnormalities.
Name 4 placental factors that can cause IUGR
Impaired trophoblast invasion, partial abruption/ infarction, chorioamnionitis, placental cyst, placental praevia
What usually causes preeclampsia and why is it associated with IUGR?
Deminished remodelling of spiral arteries in the uterus, causing decreased placental blood flow. This decreases the nutrients reaching the baby and restricting growth.
Preeclampsia is difficult to treat but what can be done to limit the damage?
Give corticosteriods to baby at birth and balance between early delivery risk and benefits.
When are at risk patients screen for IUGR?
at 24 weeks
Which centiles are most sensitive and most specific for IUGR/FGR
10th is most sensitive (everyone but some false positives)
3rd is most specific (potentially some false negatives)
What is the difference between fetal age and gestational age?
Gestational age is measure from the first day of the mothers last period.
Foetal age is from fertilisation so is usually two weeks less than GA.
What are the parameters to define preeclampsia?
Bp raised aboved 140/90 on 2 spearate occasions .4hrs apart.
proteinuria > 0.3g/day after 20 weeks
oedema
Define low birth weight and very low birth weight
LBW= <2500g
VLBW=<1500g
What are the short term risks associated with FGR?
Respiratory disress Intraventricular bleed Sepsis hypoglycaemia necroenterocolitis jaundice Electrolyte imbalances
What tests are done to determine IUGR?
PAPPA <0.3MOM
Uterine atery doppler scan 60-70% loss of function gives abnormal reading
which week and baby weight would you aim to deliver a FGR baby after?
> 28 weeks and >500g
